Thread: Maximum Tire Size vs. Rim Width??

1. Maximum Tire Size vs. Rim Width??

Purposely posting here, not in wheels and tires, but maybe it'll become a sticky somewhere.

This question seems to be forever recurring.

In the past, it seemed that if your internal rim width in cm = your tire width in inches, you were fine.

Example:
2.1" tire works great on a 2.1cm (21mm) internal rim.
2.5" tires works great on a 25mm rim.

But then you get to 2.8 or 3.0 and it seems to fall apart. It might even be a weak argument at 2.5".

If you go really big, it's nearly a factor of 2: 4.8" tire needs at least ~80mm (to 100mm rim). Granted, this is a different animal.

I think what everyone wants to read is a guideline.

This, I think, is questionable:
https://www.dtswiss.com/Technology/MTB-rim-width

Check this out too: https://www.dtswiss.com/Resources/Te..._Dimension.pdf
I think I would have a much narrower interpretation.

Shall I say, debatable.

I know the "rules" aren't hard and fast, but some guidelines maybe for the newbs?

21mm rim = 2.1" max tire
25mm rim = 2.5" max tire
30mm rim = 2.8" max tire
32mm rim = 3.0" max tire
35mm rim = 3.25" max tire

or is it more like
45mm rim = 3.25" max tire
...
...
...

-F

2. I have a 19mm internal rim (because I'm too poor to buy new ones) and ride with a 2.35 tire set up tubeless at 23-24 psi and no issues. I weigh 175ish if that matters.

3. There are too many variables in play to give blanket suggestions in my opinion. Rider weight, actual tire size, casing construction variances for a given mold (protective vs non-protective), different compounds for a given mold (full sticky vs multi-compound), intended usage, etc.

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4. Originally Posted by TheGweed
I have a 19mm internal rim (because I'm too poor to buy new ones) and ride with a 2.35 tire set up tubeless at 23-24 psi and no issues. I weigh 175ish if that matters.
^^^I tried this on my old 26er when I weighed 175#. For me, it did not work. I ended up near 40psi, then fortunately sold the rims to a buddy who was building a super lightweight bike for a lightweight rider. They did OK with 1.95-2.1 tires.

Originally Posted by tuckerjt07
There are too many variables in play to give blanket suggestions in my opinion. Rider weight, actual tire size, casing construction variances for a given mold (protective vs non-protective), different compounds for a given mold (full sticky vs multi-compound), intended usage, etc.

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I would agree with not making blanket statements, but what if we start with the DT Swiss guidelines above. I think their chart indicates what you could do, but not really what you'd want to do. They seem to recommend/allow some fairly narrow rims with wide-ish tires - which works for some, but even they might choose otherwise if they had the option or if it was easier. Adding to that confusion, it seems some mfr's even spec somewhat narrow rims on brand new plus bikes. Maybe just to drive aftermarket sales of replacement wheels.

IDK, maybe I'm thinking too much.

-F

5. Wide rims support the tire better. All other vehicles use a rim that is close to the tire size.
The main problem is that mountain bike tires are designed to fit on narrow rims because that's what was available. Now that rims are growing, tires are starting to catch up. Maxxis is making WT that give a better profile on wider rims. Tires designed for a wider rim can incorporate larger tread spacing and a more rounded shape to keep handling consistent.
In a perfect world a tire that is 60mm should be on a 50ish mm rim and have wide enough tread to protect the sidewalls.
Let's say that 35mm internal is the new normal, even a correctly engineered 53mm tire should have no trouble fitting with a desirable tread pattern and profile. Time will tell, but I believe the majority of tires will transition to fitting on wider rims.

Easton has a pressure chart also:

https://www.eastoncycling.com/media/...20pressure.pdf

Schwalbe has a lot of technical info;

http://www.skeppshult.se/media/1140/...fo-2015_gb.pdf

Surly:

7. Originally Posted by alexbn921
Wide rims support the tire better. All other vehicles use a rim that is close to the tire size.
The only other vehicles it's worth considering are other 2-wheels vehicles, as nothing else is purposely (generally) leaned over and requires a rounded profile. Essentially most other vehicles require a flat contact patch and therefore need the width to match up quite well.

It's also during a lean (cornering) where traction is most critical, aside from straight-line braking.

Wide rims still do support the tyre better though, there's no arguing that. However beyond that it's a combination of what side rim the tyre was designed around (opens/closes the tread spacing), how much protection you want to give the tyre sidewall and your rim from rocks etc, and personal preference.

As for actual figures, well the problem is that a Maxxis inch is not equal to a Schwalbe inch and so on.

8. For whatever its worth, I am running WTB Ranger TCS Light 26" 3.0 on my Kona WO's 80mm wide Mulefut rims in the rear and a Jauggernaut Pro 4.0 up front. This combo seems to work great for my Fatty bike. It lowers the profile in the rear but widened the 3.0 to 3.25 but gives very little side rim protection. I swear this set up runs really smooth. The 3.0 allows quicker initial inertia and the 4.0 allows float up front for sand and muck, all based on my uneducated theory!!! I run about 12 psi in both, generally hard-pack terrain. Not super fast but for climbing and technical stuff it's awesome and Fattys are just to fun!!!

9. Not to mention rear triangle clearance to tire width. Oops, sorry I mentioned it.

10. DT Swiss has a chart of which tire widths are acceptable with which rim widths:

https://dycteyr72g97f.cloudfront.net...WEB_ZZ_001.pdf

11. Sorry for the conspiracy theory, but I think it's all about selling more expensive wider rims after recommending them for (more expensive) wider tires. I have a very standard tire Maxxis 27.5" x 2.5 (71 mm) on a 23mm front rim. That's over a 3:1 ratio for tire to rim size. When I first saw the tire I'm like no way this is fitting, I'm going to have to buy a wider rim. Not so. Not only did it easily fit on, I've had zero problems with it in the last 8 months. I can go all the way down to 22 psi with a tube and no mushiness (over 20 psi), no rim strikes, no separation of the bead off the rim, nothing. A solid workhorse tire on the 'wrong' rim.

Maybe the more important question is: has someone on here put on a wide tire on a narrow rim and DID they have problems?

12. Originally Posted by TheGweed
I have a 19mm internal rim (because I'm too poor to buy new ones) and ride with a 2.35 tire set up tubeless at 23-24 psi and no issues. I weigh 175ish if that matters.
2.35 inches = 59mm / 19mm = 3.1x tire to rim ratio and no issues. Exactly. It's all a marketing ploy. Most of you guys seem very intelligent, and I mean that. So don't turn a blind eye to BS, look at all mfr. charts with a critical mind and what their underlying motive is: to help the biker or to make more money?

13. 27-30mm seems ideal for the majority of mtb applications i.e. Trail riding...

The above should cater to 2.2 to 2.5 inch tires.

Who needs em? The industry, that's who!!

:cha-ching:

'We'll all make it to the top... Some of us, might not make it to the bottom'

14. Originally Posted by richj8990
2.35 inches = 67mm / 19mm = 3.5x tire to rim ratio and no issues. Exactly. It's all a marketing ploy. Most of you guys seem very intelligent, and I mean that. So don't turn a blind eye to BS, look at all mfr. charts with a critical mind and what their underlying motive is: to help the biker or to make more money?
2.35" = 59.7mm

15. Originally Posted by richj8990
I have a very standard tire Maxxis 27.5" x 2.5 (71 mm) on a 23mm front rim.

That's odd because my 2.5 DHF II on a 30mm internal rim measures 61mm.

16. Originally Posted by richj8990
Sorry for the conspiracy theory, but I think it's all about selling more expensive wider rims after recommending them for (more expensive) wider tires. I have a very standard tire Maxxis 27.5" x 2.5 (71 mm) on a 23mm front rim. That's over a 3:1 ratio for tire to rim size. When I first saw the tire I'm like no way this is fitting, I'm going to have to buy a wider rim. Not so. Not only did it easily fit on, I've had zero problems with it in the last 8 months. I can go all the way down to 22 psi with a tube and no mushiness (over 20 psi), no rim strikes, no separation of the bead off the rim, nothing. A solid workhorse tire on the 'wrong' rim.

Maybe the more important question is: has someone on here put on a wide tire on a narrow rim and DID they have problems?
World Cup DH riders are running 2.5" tires on rims that are around 25mm wide, give or take a couple mm either way. They put far worse loads on their tires than us mortals can ever dream of yet I don't see them jumping on the wide rim trend. These are guys who will happily run non-sponsor tires & equipment if it helps them win a race, you'd think that if wide rims give all the advantages which are claimed by their proponents that DH racers would be all over them. Oh, wait, it happened already. 20 years ago. Sun Doublewides and 3" Gazzaloddis anyone? It seems we haven't learned from past mistakes.

17. Originally Posted by aerius
World Cup DH riders are running 2.5" tires on rims that are around 25mm wide, give or take a couple mm either way. They put far worse loads on their tires than us mortals can ever dream of yet I don't see them jumping on the wide rim trend. These are guys who will happily run non-sponsor tires & equipment if it helps them win a race, you'd think that if wide rims give all the advantages which are claimed by their proponents that DH racers would be all over them. Oh, wait, it happened already. 20 years ago. Sun Doublewides and 3" Gazzaloddis anyone? It seems we haven't learned from past mistakes.
And for the fastest the entire thing is a gamble. They are willing to sacrifice durability for a slightly faster time. Look at all of the tire failures over the past season.

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18. Originally Posted by tuckerjt07
And for the fastest the entire thing is a gamble. They are willing to sacrifice durability for a slightly faster time. Look at all of the tire failures over the past season.

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It's claimed that for a given tire pressure and tire, wide rims will give better tire support, more resistance to pinch flats & burps, and increased traction for a zero to minimal gain in rolling resistance. If the above is true, it would be a massive advantage for DH racing since it would allow for significantly higher cornering speeds and better ability to plow through rough terrain without pinch flatting tires or rolling them off the rims. So why is it that DH racers use rims in the 25mm range?

19. Originally Posted by aerius
It's claimed that for a given tire pressure and tire, wide rims will give better tire support, more resistance to pinch flats & burps, and increased traction for a zero to minimal gain in rolling resistance. If the above is true, it would be a massive advantage for DH racing since it would allow for significantly higher cornering speeds and better ability to plow through rough terrain without pinch flatting tires or rolling them off the rims. So why is it that DH racers use rims in the 25mm range?
You answered your own question, "minimal gain in rolling resistance". All the above apply but that can make or break a run. For the fastest it's a crap shoot. There's also the fact that they are pushing harder and with the way they ride a wider rim may be prone to damage.

Attempting to use a world class pro's choice in anything to justify an amateur's decision is foolish. There is no direct comparison to be made.

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20. Originally Posted by tuckerjt07
Attempting to use a world class pro's choice in anything to justify an amateur's decision is foolish. There is no direct comparison to be made.
And most amateurs wouldn't know what's good for them if they were beaten over the head with it. The continued popularity of RockShox forks, Stan's rims, and Hans Dampf tires is proof of this.

21. I used to hit rim, burp air and sealant with 2.3's on 29mm rims at 20 psi front and rear. Same tires on my current 21mm rims at same air pressure and ZERO issues. No rim strikes or burping. My 21's are way lighter too. Win/win. Drink the koolaid if you must.

22. Originally Posted by aerius
And most amateurs wouldn't know what's good for them if they were beaten over the head with it. The continued popularity of RockShox forks, Stan's rims, and Hans Dampf tires is proof of this.
Then it logically follows that they would not know what was bad either. Ergo, unless your name is Gwin, Minaar, Hart, Bruni, etc., you've just refuted your own argument. Excellent work.

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23. Originally Posted by HacksawReynolds
I used to hit rim, burp air and sealant with 2.3's on 29mm rims at 20 psi front and rear. Same tires on my current 21mm rims at same air pressure and ZERO issues. No rim strikes or burping. My 21's are way lighter too. Win/win. Drink the koolaid if you must.
Which makes absolute sense. However your tires now do not undergo as much deformation and therfore have less traction now. There is always a trade off.

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24. Originally Posted by tuckerjt07
Which makes absolute sense. However your tires now do not undergo as much deformation and therfore have less traction now. There is always a trade off.

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Traction, that I can tell from riding hasn't been any worse. I mean it's a 29er at 20psi. If one is having traction issues with that setup one must look at their riding technique and not their equipment IMO.

The tire profile is much better with my 21's than with my 29's as well.

25. Originally Posted by HacksawReynolds
Traction, that I can tell from riding hasn't been any worse. I mean it's a 29er at 20psi. If one is having traction issues with that setup one must look at their riding technique and not their equipment IMO.

The tire profile is much better with my 21's than with my 29's as well.
You would likely only notice it if you were regularly flirting with the limit. However, there will be less available traction due to the fact you made the system less supple.

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26. Originally Posted by tuckerjt07
Then it logically follows that they would not know what was bad either. Ergo, unless your name is Gwin, Minaar, Hart, Bruni, etc., you've just refuted your own argument. Excellent work.

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And that is why the bike industry refuses to progress and continues repeating past mistakes. Which is why better riders such as myself have a hard time finding stuff that doesn't suck.

27. Originally Posted by aerius
And that is why the bike industry refuses to progress and continues repeating past mistakes. Which is why better riders such as myself have a hard time finding stuff that doesn't suck.
Or, idea, maybe you aren't as good as you think you are. You've already said that you have no way of knowing if something is good or bad so...

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28. Originally Posted by tuckerjt07
there will be less available traction due to the fact you made the system less supple.
Less supple maybe, but far more functional/reliable.

29. For me the exception to the rule is if you are running 26" wheels, the extra diameter provided by a big tire is more beneficial than sidewall performance. I noticed a big difference in bike ability when going from 2.2 to 2.5 even though my rims had no business running 2.5. The extra diameter was immediately noticeable for rocky climbs where the bike didnt get hung up on stuff as much, there was one obstacle I could never clear until I got 2.5's and suddenly my bike just rolled up and over it rather than coming to a dead stop.

On a 29er I dont like running tires that are too wide. I found 2.35 Schwalbe's on a 21mm rim too wide and even on a 26mm rim I wish they were a bit skinnier. I will probably try 2.3 Maxxis next.

30. Originally Posted by idividebyzero
For me the exception to the rule is if you are running 26" wheels, the extra diameter provided by a big tire is more beneficial than sidewall performance. I noticed a big difference in bike ability when going from 2.2 to 2.5 even though my rims had no business running 2.5. The extra diameter was immediately noticeable for rocky climbs where the bike didnt get hung up on stuff as much, there was one obstacle I could never clear until I got 2.5's and suddenly my bike just rolled up and over it rather than coming to a dead stop.

On a 29er I dont like running tires that are too wide. I found 2.35 Schwalbe's on a 21mm rim too wide and even on a 26mm rim I wish they were a bit skinnier. I will probably try 2.3 Maxxis next.
I noticed the exact same thing on a 26" bike. For my 27.5" bike, going from 2.1 to 2.5 was nicer, more solid, no drama, an 'improvement'. For my 26" bike, going from 1.95 to 2.4 was huge. It was like a completely different bike. I went from out of control downhill and being forced to take every microtrack the 1.95 tire chose to actually going down the hill with some control. Rim size is only 19 mm (3.6x tire/rim width). Huge difference even if the tire is too wide for the rim. Lowering the psi from 35 to 25 helped a lot too.

BTW about that 2x tire width to rim width rule, it's actually not a rule:

https://www.bikerumor.com/2016/08/12...-best-results/

"...with some calculations of the ETRTO standards, we came up with a rough guideline suggesting your rim width should be between 32% to 70% of the tire width. For a 2.8″ tire, that means rims with an internal width of 23mm to 49mm. Based on all of these conversations behind this story, our hunch is that the “ideal standard” lies near the upper middle of that range, so something like a 35-40mm IW rim would be the best starting point for safety, optimized performance and a good tire profile. Disclaimer: That’s our math and opinion based on the charts and excludes the narrowest tire width fringes, so use at your own risk."

Also:

“It is primarily based on experience, testing, and feedback from our customers as well as the professional athletes we work with. The basics are that if you run a rim that is too wide for a particular tire you have a lot more issues with tire and rim damage, as the rim is much more likely to bottom out on lateral rock impacts causing tire or rim damage.

“Conversely, if the tire is too wide for a given rim, you get more tire roll due to the larger casing size and higher aspect ratio of the tire, which together create more leverage on the tire allowing the casing to collapse and roll over the rim during hard cornering."

They are basically saying it's a lesser evil to run too wide of a tire for the rim than to run too narrow of a tire for the rim. That 32-70% they referenced above for tire to rim width for a 2.8 inch-wide tire came out for them 23mm to 49 mm for the rim. My math (2.8 inches = 79mm) came out instead to 25mm to 55mm for the rim. However, I'm going to try a 26 x 2.8 tire and my XC rim is only 19mm wide (4.2x ratio) so I'll play it safe and buy a wider rim anyway.

31. Originally Posted by richj8990
...

BTW about that 2x tire width to rim width rule, it's actually not a rule:

https://www.bikerumor.com/2016/08/12...-best-results/

"...with some calculations of the ETRTO standards, we came up with a rough guideline suggesting your rim width should be between 32% to 70% of the tire width. For a 2.8″ tire, that means rims with an internal width of 23mm to 49mm. ...
Ha ha
That's a difference of over 100%!
I see how these guidelines work: Do whatever you want.

-F

32. Originally Posted by Fleas
Ha ha
That's a difference of over 100%!
I see how these guidelines work: Do whatever you want.

-F
Exactly. That link is really informative: https://www.bikerumor.com/2016/08/12...-best-results/

You know what's embarrassing, I've been using 28.3 as an inch/mm conversion and forgot it was 25.4 and not 28.3 (28.3 is ounces to grams). DOH! This is what happens when you don't work in science for 9 years, brain mush.

These are all general guidelines in the link's discussion. Anything up to 3x tire width to internal rim width is probably fine. You can go above 3x but I for sure would not go over 4x.

BTW for anyone who still thinks that going over 2x the tire width compared to rim width is bad:
after spending hours looking at 26" rims yesterday, I guess it was not a total waste of time because I learned the standard internal rim width is 19mm, or 559 x 19. The standard tire width is 26 x 1.95. 1.95 x 25.4 = 50mm. 50mm / 19mm = 2.6x tire width to internal rim width ratio. So above 2x is NORMAL.

My Maxxis 27.5 x 2.5 (64mm wide) is on a 23mm internal width rim = 2.8x = OK

My (off-brand?) CST Rock Hawk 26 x 2.4 (61mm wide) is on a 21mm internal width rim = 2.0x = OK.

After looking for hours and hours yesterday online trying to find a reasonably priced 26+ wheelset, and not finding it, then...taking the same wheel above, adding Maxxis 26 x 2.8 (71mm wide) / 21mm rim width = 3.4x, over 3.0x but still under 4.0x so worth trying.

According to the link, if you have a tire over 3x the internal rim size and you take corners aggressively, there is a chance that the outside of the tire can fold over the rim and may cause a pinch flat or worst case the tire may even start sliding off the rim. So aggressive riders should not go over 3x tire to rim width. I don't really do that so hopefully I'll be fine and not end up flung off the trail corner lol.

Last but not least, tire height (or length, as will be mentioned below) is important too for many reasons, including if they fit on your bike; it's not just width that should be measured. I see a lot of discussion now about 29 vs. 27.5+. A 27.5 x 3.0 tire is just as tall as a 29 x 2.3 tire. And you are getting 0.7 inches wider for the tire, same height = winner. So to me it's a no-brainer, go 27.5+ if you can. But if you have a stock 27.5" bike there can be problems...

Going back to the 26 x 2.8 tire I want to put on my bike; there's one little problem: it won't fit under the fork arch. Right now it has the aforementioned 26 x 2.4 tire, and the space between the top of the tire and the fork arch is only 0.4 inches. If you take the 27.5 x 3.0 being as tall as the 29 x 2.3 tire, then 0.7 inches wider = 1.5 inches higher, or 0.1 inches wider = 0.215 inches higher. Remember this ratio: 0.1 inch wider = 0.215 inches higher / longer. If I go from 2.4 inches wide to 2.8 inches wide, then a 0.4 inch difference in width = 0.86 inches higher. That's 0.46 inches above the bottom of the fork arch = cannot fit. So I'll have to get a 27.5" fork on the 26" bike to make it fit (and that's not the end of the world, sorry 26" purists).

The same issue applies on the back of the bike. It's not necessarily the width of the tire clearing the triangle and not hitting the chain. It's the length of the tire hitting the back of the front derailleur if you have a 2x or 3x drivetrain. 1x maybe no issue with a wider tire, 2x or 3x = major issue. Right now I have a 26 x 2.25 inch tire on the back and it's only 0.25 inches away from the front derailleur. I can't go 26 x 2.4 on back because 0.15 inches wider = 0.32 inches longer, and rubbing into the front derailleur in the 1st chainring = cannot do. Similarly, I have a 27 x 2.35 inch tire in back and again it's 0.25 inches from the front. If I went 27 x 2.5 then 0.15 inches wider (again) = 0.32 inches longer and rubbing into the front derailleur again. So gentlemen it's not just girth that matters it's length too.

33. Originally Posted by Fleas
I see how these guidelines work: Do whatever you want.

-F
Exactly.

There are so many factors that come into play, so many different rim types, tires, frames, hubs, etc. that it's virtually impossible to generate any sort of true "guideline".

You want your own guideline? Take your bike with your wheels, into your LBS with a mechanic you trust, and ask them to show you just exactly what they think, what tires will work with your bike, for your kind of riding and terrain, and why.

34. Slightly OS, but what is the consensus on tire clearance from chain stays? I know depends on conditions, but for starters, let say 80% dry 20% muddy. Or another way answering, clearance on dry vs clearance on mud? Some assumptions 1) stiff wheels (carbon rims) 2) medium knobs (not DH) 3) Carbon frame.

35. Originally Posted by Simplemind
Slightly OS, but what is the consensus on tire clearance from chain stays? I know depends on conditions, but for starters, let say 80% dry 20% muddy. Or another way answering, clearance on dry vs clearance on mud? Some assumptions 1) stiff wheels (carbon rims) 2) medium knobs (not DH) 3) Carbon frame.
I’ve ran tire clearance of a 1/8” on my chain stays for years without issue. But I run in dry conditions. In muddy conditions this could be a problem. Plus you better have a quality wheel that stays trued.

36. Originally Posted by Simplemind
Slightly OS, but what is the consensus on tire clearance from chain stays? I know depends on conditions...

37. Yes, and a fine answer it is!

38. I was chatting with some friends about this. I told him my hypothesis about wide rims was more about people not being good enough to lean the bike over into the side knobs. So the wider wheels help get the side knobs into an easier position to reach, requiring less lean angle. They all agreed that it might be true. One is also a strong descender.

I'm racing XC with 2.35 on my 21mm wheels. My Enduro has a 2.6 on a 29mm wheel.

39. Originally Posted by DIRTJUNKIE
I’ve ran tire clearance of a 1/8” on my chain stays for years without issue. But I run in dry conditions. In muddy conditions this could be a problem. Plus you better have a quality wheel that stays trued.
If you can't break a spoke, you can't have fun...

40. Originally Posted by aerius
And most amateurs wouldn't know what's good for them if they were beaten over the head with it. The continued popularity of RockShox forks, Stan's rims, and Hans Dampf tires is proof of this.
LOL I was wondering about that too. I'm a beginner and all three of those names above are often twice as expensive for what the equivalent product is from the competitors. I just go with what works. Who cares what brand name is on your bike if the goal is to have fun. Some guys even buy a \$3 Rock Shox logo off e-bay to stick on their off-brand fork. What a joke.

41. Originally Posted by Zowie
If you can't break a spoke, you can't have fun...
What if you break a rear derailleur on a spoke, is that supposed to be fun?

42. Originally Posted by Sidewalk
I was chatting with some friends about this. I told him my hypothesis about wide rims was more about people not being good enough to lean the bike over into the side knobs. So the wider wheels help get the side knobs into an easier position to reach, requiring less lean angle. They all agreed that it might be true. One is also a strong descender.

I'm racing XC with 2.35 on my 21mm wheels. My Enduro has a 2.6 on a 29mm wheel.

Actually from the pictures I've seen of the tires that are less than 1.7x tire to rim it's the opposite; the side knobs are gone and pointed up. I wish there was a thread dedicated to all of the problems with too narrow of a rim, and then too wide of a rim, or a poll, and then you could really see the real-world difference. I rarely read anyone complaining that their tire is too wide for the rim (in fact I can't remember ever reading that!!!), but there are several complaints on here about rims being too wide. Yes, there is some floppiness with a larger ratio like 3x tire to rim, but some people call that cushion. Cushion can be nice especially on a hardtail. It doesn't mean the tire is going to fall off or slide off the trail.

Conversely, I've seen many posts and some pictures with a wide rim where the tire's side knobs are gone, they are pointing up instead of out, the knobs are all crowded together, the rider says rolling resistance is annoyingly high, the tire wears out a lot faster, etc. It just does not look right. As for the wider tire on a standard rim, it's not really a bulb shape. It's more like an ice cream cone or hot air balloon shape; the sidewalls slowly and firmly grow out to the side knobs in a cone shape. It's not really as floppy as you may think if the tire is a heavy 2 lbs or so and the sidewalls are thick.

There is absolutely nothing to worry about, this is all rim manufacturer hype. Now if you actually tried a wider tire on a narrow rim and it sucked, please reply with exactly how it sucked, how riding was affected, so people can make a practical case for wider rims, instead of just taking everything as gospel from the for-profit bike industry. If the bike industry thinks you will believe something, they will simply add that to their sales pitch, whether it's true or not. The argument "The manufacturer recommends blah blah blah" is not an argument. We need to see real feedback from people trying vastly different ratios, 1.5x to 3.5x. If someone just tried 1.7x and never anything else, they would not know the difference. It may work fine to them but it's a different tire and rim than what they had before so there is no real experiment or conclusion.

43. Originally Posted by richj8990
Actually from the pictures I've seen of the tires that are less than 1.7x tire to rim it's the opposite; the side knobs are gone and pointed up. I wish there was a thread dedicated to all of the problems with too narrow of a rim, and then too wide of a rim, or a poll, and then you could really see the real-world difference. I rarely read anyone complaining that their tire is too wide for the rim (in fact I can't remember ever reading that!!!), but there are several complaints on here about rims being too wide. Yes, there is some floppiness with a larger ratio like 3x tire to rim, but some people call that cushion. Cushion can be nice especially on a hardtail. It doesn't mean the tire is going to fall off or slide off the trail.

Conversely, I've seen many posts and some pictures with a wide rim where the tire's side knobs are gone, they are pointing up instead of out, the knobs are all crowded together, the rider says rolling resistance is annoyingly high, the tire wears out a lot faster, etc. It just does not look right. As for the wider tire on a standard rim, it's not really a bulb shape. It's more like an ice cream cone or hot air balloon shape; the sidewalls slowly and firmly grow out to the side knobs in a cone shape. It's not really as floppy as you may think if the tire is a heavy 2 lbs or so and the sidewalls are thick.

There is absolutely nothing to worry about, this is all rim manufacturer hype. Now if you actually tried a wider tire on a narrow rim and it sucked, please reply with exactly how it sucked, how riding was affected, so people can make a practical case for wider rims, instead of just taking everything as gospel from the for-profit bike industry. If the bike industry thinks you will believe something, they will simply add that to their sales pitch, whether it's true or not. The argument "The manufacturer recommends blah blah blah" is not an argument. We need to see real feedback from people trying vastly different ratios, 1.5x to 3.5x. If someone just tried 1.7x and never anything else, they would not know the difference. It may work fine to them but it's a different tire and rim than what they had before so there is no real experiment or conclusion.
Originally Posted by richj8990
I'm a beginner
Why should anyone lend even a teensy-tiny amount of credibility to any of your claims?

44. Originally Posted by richj8990
What if you break a rear derailleur on a spoke, is that supposed to be fun?
Doesn't matter what I think.
Do you think it sounds like fun?

45. Originally Posted by Zowie
Doesn't matter what I think.
Do you think it sounds like fun?
I've done it. I dunno what happened but it cracked the frame because it was a cheap bike that didn't have a derailleur hanger. Parked it next to a trash bin and let the homeless have at it.

46. Originally Posted by Sidewalk
I was chatting with some friends about this. I told him my hypothesis about wide rims was more about people not being good enough to lean the bike over into the side knobs. So the wider wheels help get the side knobs into an easier position to reach, requiring less lean angle. They all agreed that it might be true. One is also a strong descender.

I'm racing XC with 2.35 on my 21mm wheels. My Enduro has a 2.6 on a 29mm wheel.

One thing I forgot to mention, a lot of reviewers say that wider tires really help beginners more than anyone else. If the converse is true, then pros can get away with a more skinny tire because of their skill and experience level. Whether that extrapolates over to rims or not, I dunno but it very well could.

47. Which Rockshox forks are 3 times as much as the comparable competitors? Fox isn't cheaper. Manitou is a bit cheaper if you look for good deals, but nowhere near 3 times cheaper. XFusion? Ohlins? DVO? If you're referring to Suntour or one of those Chinese brands, you're comparing apples to oranges, or at best red delicious apples to my daughter's plastic toy apples.

48. Originally Posted by richj8990
One thing I forgot to mention, a lot of reviewers say that wider tires really help beginners more than anyone else. If the converse is true, then pros can get away with a more skinny tire because of their skill and experience level. Whether that extrapolates over to rims or not, I dunno but it very well could.
Don't listen to a lot of reviewers.

49. Originally Posted by richj8990
One thing I forgot to mention, a lot of reviewers say that wider tires really help beginners more than anyone else. If the converse is true, then pros can get away with a more skinny tire because of their skill and experience level. Whether that extrapolates over to rims or not, I dunno but it very well could.
You are correct.

You dont know.

But at least your’re very consistently ignorant!

50. Originally Posted by richj8990
I've done it. I dunno what happened but it cracked the frame because it was a cheap bike that didn't have a derailleur hanger. Parked it next to a trash bin and let the homeless have at it.
IMHO it seems like more fun to fold a wheel, but I take what I can get.

51. Originally Posted by fillaroida
You are correct.

You dont know.

But at least your’re very consistently ignorant!

Then please enlighten us on any facts that wider rims truly help + tires in all riding situations for all riders. Please, be my guest, post links to this factual, proven information. Or can you?

52. Originally Posted by fillaroida
Why should anyone lend even a teensy-tiny amount of credibility to any of your claims?
https://www.bikerumor.com/2016/08/12...-best-results/

Because I post factual information, not just unconstructive criticism. And if my opinions are wrong, I change them, unlike arrogant elitists. I asked for real feedback and I get sniping with zero description of experience on + rims. It's quite easy to flame someone on here, it's another matter to have the intelligence and courtesy to actually answer the posted question.

53. Tire and rim need to work together as a system. If a tire was designed for a 17mm rim and you but it on a 30mm rim it will probability suck. With that said 2.1-2.35 are much better on 25 then 17 rims. 25-30 is a sweet spot and 35+ needs a specific design or larger tire. I hope that 30-35 becomes the standard for all mountain bike tires from 2.2 to 2.6 it gives a good support and volume ratio without to much added weight.
LOL wider tires are only for newbs. Same thing for wide bars and dropper posts. I heard a rumor that all riders should start on full ridged too.

54. Originally Posted by Simplemind
Slightly OS, but what is the consensus on tire clearance from chain stays? I know depends on conditions, but for starters, let say 80% dry 20% muddy. Or another way answering, clearance on dry vs clearance on mud? Some assumptions 1) stiff wheels (carbon rims) 2) medium knobs (not DH) 3) Carbon frame.
Depends on how much you weigh, how stiff your frame is, how much power you can put down, and how hard you corner. I like to have at least 1/4", preferably closer to 1/2". It's not just rims that can get knocked out of true, tires can as well. If you do enough stupid stuff on your bike, you can put sizable wobbles into the tire casing and if that happens you'll want some extra clearance on the frame. Frames also flex under load so that needs to be taken into account as well.

55. Originally Posted by alexbn921
I heard a rumor that all riders should start on full ridged too.
It's way more fun to put 'very experienced' mountain bikers on rigids...

56. Originally Posted by alexbn921
With that said 2.1-2.35 are much better on 25 then 17 rims. 25-30 is a sweet spot.
I disagree.

If I end up going to 2.6 up front I'll run a 25 rim instead of my 21 for it.

57. Originally Posted by Zowie
It's way more fun to put 'very experienced' mountain bikers on rigids...
ALL new riders young and old should ride full rigid and steer clear of silly brown sidewalk "flow" trails for at least 5 years before pu\$\$y-ing up to the latest technology and metrosexual trail designs.

58. Originally Posted by richj8990
Because I post factual information, not just unconstructive criticism. And if my opinions are wrong, I change them, unlike arrogant elitists.
Yo! Newb! You're using "factual" and "opinions" interchangeably. FYI, they are not synonyms.

Let's look at some of the "factual information" that you have posted:

"Yes, there is some floppiness with a larger ratio like 3x tire to rim, but some people call that cushion. Cushion can be nice especially on a hardtail. It doesn't mean the tire is going to fall off or slide off the trail."

This is false.

Large tires on narrow rims, in full light bulb mode, can be less fun because square tread profile becomes very rounded which reduces grip and leads to casing flop.

"Conversely, if the tire is too wide for a given rim, you get more tire roll due to the larger casing size and higher aspect ratio of the tire, which together create more leverage on the tire allowing the casing to collapse and roll over the rim during hard cornering"

"As for the wider tire on a standard rim, it's not really a bulb shape. It's more like an ice cream cone or hot air balloon shape; the sidewalls slowly and firmly grow out to the side knobs in a cone shape. It's not really as floppy as you may think if the tire is a heavy 2 lbs or so and the sidewalls are thick."

Again, this is false but does confirm that you are a beginner with practically zero riding experience on different rim and tire combos.

"There is absolutely nothing to worry about, this is all rim manufacturer hype."

Again, this is false. What do you hope to accomplish by posting this nonsense?

"If the converse is true, then pros can get away with a more skinny tire because of their skill and experience level. Whether that extrapolates over to rims or not, I dunno but it very well could."

This is truly the funniest bit of nonsense that you posted. Due to your lack of experience, it's no wonder you can't understand how stupid that two sentence combination is.

"Then please enlighten us on any facts that wider rims truly help + tires in all riding situations for all riders."

This is a straw man (Google it). I never made that claim.

Get out there and ride some different setups - it might help with your confusion!

59. Car tires have a published recommended rim width range. I think it would be nice if MTB tires did too (a few do). I don't think it is just the tire size, but the tire design as well.

Stans has a guide on their website. They tend to go narrower on the rim width than what is considered the norm.

Anyway, here are a few I've tried:

Hans Dampfs 2.35s on i17 rims - very unstable on cornering.
Hans Dampfs 2.35s on i25.5 rims - whole new tire, could be drifted without dropping you.
Hans Dampfs 2.35s on i35 rims - Even more stable on corners. However IMO too stable at times, there was no sideways compliance, so it rode harder when leaned over on bumpy corners. Pressures could not be dropped further, because rim strikes were still the limiting factor. Also, sidewalls were exposed and wore out before the tread did. Rims were getting scraped too.

Dirt Wizard 3.0 60tpi on i35s - IMO the rim width was perfect for this tire. Due to the very heavy casing, there was no floppiness when leaning the bike over. Sidewalls and rim were very protected of course.

Nobby Nic 2.6 on i35s - Feels about right to me in this case as well. The casing is light, so there is a touch of squirm when leaned over at lower pressures, but not in a negative way. Sidewall wear is a moderate problem though.

60. Originally Posted by fillaroida
"If the converse is true, then pros can get away with a more skinny tire because of their skill and experience level. Whether that extrapolates over to rims or not, I dunno but it very well could."

This is truly the funniest bit of nonsense that you posted. Due to your lack of experience, it's no wonder you can't understand how stupid that two sentence combination is.
You can't see the forest for the trees anymore.

61. Originally Posted by Lombard
DT Swiss has a chart of which tire widths are acceptable with which rim widths:

https://dycteyr72g97f.cloudfront.net...WEB_ZZ_001.pdf
According to this you can run an 81mm tire on an 80mm rim. That's fun.

62. I have an Enve XC wheelset with a 19mm inner with a Nobby Nic 2.35 tire and it feels great. I would have no problem putting a Maxxis Ardent 2.4 on this rim either. Sometimes I think people spend more time pontificating about a bunch of BS than they do riding. LOL

63. Totally^^^^^^^^

64. Originally Posted by alexbn921
Tire and rim need to work together as a system. If a tire was designed for a 17mm rim and you but it on a 30mm rim it will probability suck. With that said 2.1-2.35 are much better on 25 then 17 rims. 25-30 is a sweet spot and 35+ needs a specific design or larger tire. I hope that 30-35 becomes the standard for all mountain bike tires from 2.2 to 2.6 it gives a good support and volume ratio without to much added weight.
LOL wider tires are only for newbs. Same thing for wide bars and dropper posts. I heard a rumor that all riders should start on full ridged too.

Have you seen a standard tire on a 35mm rim? Have you seen what position the 'side' knobs are in? I'm not going to give you the answer to that question, go see for yourself and then rethink if that standard tire is optimized to that rim size.

65. Originally Posted by HacksawReynolds
I disagree.

If I end up going to 2.6 up front I'll run a 25 rim instead of my 21 for it.

He actually said 25mm is better for 2.6, he agreed with you, or you agreed later with him. Getting my first 25mm front wheel in the mail today, WTB i25 CANNOT WAIT!!!

BTW 2.6 = 66mm / 25mm = 2.6x tire to rim ratio = FINE, not to beat a dead horse or anything. I agree 66mm / 21mm = 3.1x tire to rim ratio, not optimal, not the greatest, doable but floaty and I agree it's a bit much.

66. Originally Posted by alexbn921
Wide rims support the tire better. All other vehicles use a rim that is close to the tire size.
The main problem is that mountain bike tires are designed to fit on narrow rims because that's what was available. Now that rims are growing, tires are starting to catch up. Maxxis is making WT that give a better profile on wider rims. Tires designed for a wider rim can incorporate larger tread spacing and a more rounded shape to keep handling consistent.
In a perfect world a tire that is 60mm should be on a 50ish mm rim and have wide enough tread to protect the sidewalls.
Let's say that 35mm internal is the new normal, even a correctly engineered 53mm tire should have no trouble fitting with a desirable tread pattern and profile. Time will tell, but I believe the majority of tires will transition to fitting on wider rims.

The question is: where are the side knobs going to be if the tire to rim ratio is only 1.2x?

The answer: the side knobs will not be on the side anymore, they will be grouped in with the center knobs. I don't see how that will help traction. I do see how it will increase rolling resistance and treadwear. Maybe that's what the MTB manufacturers want, more expensive parts and more expensive tires that wear out faster on those parts = more profit.

From JC Wages, regarding a 1.7x tire to rim ratio: Straight line traction will likely improve but cornering traction at anything beyond very slight lean angles will be poor and cause abrupt traction loss.

2.0x to 3.0x tire to rim is optimal for everything standard and probably up to 2.8 to 3.0, maybe even them too, we'll have to see the real data in the next few years.

67. Originally Posted by richj8990
Actually from the pictures I've seen of the tires that are less than 1.7x tire to rim it's the opposite; the side knobs are gone and pointed up.
You are basically agreeing with me. I'm saying that the side knobs are so far towards facing straight up, that the people who aren't leaning the bike over enough to get a bite are also not suffering from hitting gaps in the lugs from transitioning from center to side lugs.

I don't agree with the belief that a narrower tire is better for a faster rider. I think the faster rider is more capable of choosing what is better for him/her. I produce less power than my rivals, but am a better bike handler. Being able to make up time, or even recover on the DH or twisty bits in a race makes the small weight penalty worth the traction. I saw it just this weekend in a race where I was closing gaps or holding people's wheels where I was able to flow, or at least spike power less, compared to the guys who were faster overall.

The 2.6 on my enduro has awarded me a few DH KOM's. I don't think a beginner is taking a DH KOM from a former pro DH racer on a past Pro enduro stage*

*Trail conditions change, I'm not claiming to be better than them. But being in the ballpark I think excludes me from being "beginner".

68. Originally Posted by richj8990
The answer: the side knobs will not be on the side anymore, they will be grouped in with the center knobs. I don't see how that will help traction. I do see how it will increase rolling resistance and treadwear. Maybe that's what the MTB manufacturers want, more expensive parts and more expensive tires that wear out faster on those parts = more profit.
I think we agree that standard tires on a 35mm rim is a not the best. The tire takes a square shape and turns the side knobs up. Bad all the way around.
I like big tires and big tires should have a rim that supports the sidewalls and gives the proper profile. My bike will take a 2.4 tire in the back and Maxxis makes a wide trail tires that have the proper profile and spacing on a 35mm rim.

Now if I want to do an XC race and run smaller tires I need to buy different rims. They are not designed for 35mm rims, but they could/should be. Changing the casing of the tire and spacing the knobs just like they do going from 27.5 to 29er tires of the same kind.

I don't know where the optimum ratio of tire to rim will play out. My hope is the 30-35 will become the norm, just like 21-25 internal road rims are becoming the new standard.
17mm rims suck for tires over 2.1
23-26 sweet spot for old 2.1-2.35 tires
30-35 sweet spot for 2.4-2.6 tires and hopefully all tires over 2.25 in the future.

69. Originally Posted by richj8990
He actually said 25mm is better for 2.6, he agreed with you, or you agreed later with him. Getting my first 25mm front wheel in the mail today, WTB i25 CANNOT WAIT!!!

BTW 2.6 = 66mm / 25mm = 2.6x tire to rim ratio = FINE, not to beat a dead horse or anything. I agree 66mm / 21mm = 3.1x tire to rim ratio, not optimal, not the greatest, doable but floaty and I agree it's a bit much.
Ya I was referring to the other bologna numbers he was spewing.

70. 2.3 is better on 21mm than on 29mm.

71. Originally Posted by HacksawReynolds
2.3 is better on 21mm than on 29mm.
Soooooo..... this rim WTB STP i29 TCS doesn't play well with Maxxis Tomahawk 27.5 x 2.3"?

Soooooo..... this rim WTB STP i29 TCS doesn't play well with Maxxis Tomahawk 27.5 x 2.3"?
DHF 29 x 2.3 on WTB STP i29 TCS paled in comparison to the same tires on my roval 21mm internal width rim. Lots of rim strikes and rim damage with the wider rims and profile better with 21mm. 29mm too square. Plus my 21's are way lighter and haven't had to true them once. Can't say the same for the 29mm rims.

73. Originally Posted by HacksawReynolds
2.3 is better on 21mm than on 29mm.
Amen, keep it over 2.0x tire to rim. 2.3 on 21mm is 2.8x (fine); 2.3 on 29mm is 2.0x.

74. Originally Posted by richj8990
Amen, keep it over 2.0x tire to rim. 2.3 on 21mm is 2.8x (fine); 2.3 on 29mm is 2.0x.
Huh. Interesting theory.

You get that 2.8 to play nice with your 'optimal' rim yet?

75. Originally Posted by richj8990
Amen, keep it over 2.0x tire to rim. 2.3 on 21mm is 2.8x (fine); 2.3 on 29mm is 2.0x.
Again with this goofy crap. It's funny.

What experience do you base this magic formula, and your subsequent recommendations, on?

Did your magic formula contribute to this (Help! Getting 2.8 tire on 25mm internal rim, tried everything, LBS mount is \$15) mess?

If you struggle to simply mount a tire on a rim, why in the world should anyone take your advice?

FWIW, on my 25mm ID rims, my 1.25" and 1.57" tires work really well. Magic formula?

76. Originally Posted by Zowie
Huh. Interesting theory.

You get that 2.8 to play nice with your 'optimal' rim yet?

I see I have a new troll (not you, you are cool). Will most likely finally ride the 2.8 Sunday. The cool thing is the tire seems to be fairly short; shorter than I calculated for height, as in shorter than 27.4 inches high on paper, which means it could actually fit inside my standard 26" fork and not just a 27.5" fork.

77. Eight or nine out of ten people can't remember to properly air up their tires.
Is that the rim's fault or the tire's?

If you're trying to get the people here to quit thinking a set of ratios of the 'right' numbers in the 'right' places makes something ride well, good luck with that.

I'd say the proof of the pudding is in the eating of it, but I guess a successful theoretical argument of how the pudding is great works too on the interwebs.

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