tires / inflation- Mtbr.com

1. ## tires / inflation

So, right now I'm using the stock bontrager jones xr with tubes. I have the inflation at around 38 psi. I weigh 185 lbs.

When I look at the tread after a sesh, it seems like most of the dirt is concentrated at the center of the tires. The outer 10% of the tread on each side of each tire is dirty of course, but not nearly as dirty as the inner 80%.

Does this mean I have some room to drop the psi? I've been told that for heavier guys like myself, anything below 40 psi is asking for pinch flats when using non-tubeless tires, and especially when using bonty tires.

Thanks.

2. Depends of how and where you ride. I run over 50 PSI, still get occasional pinch flats. My weight must be like 75-80 kg (170-180 lbs).
Beside pinch flats, softer tires reduce control on turns, so I stick to higher air pressure.

3. The mud coverage is irelevant, it just means you can lean your bike a lot further and still have traction.

Tyre pressure depends on how hard you rider, what type of terrain and your weight.

You can probably get away with about 20psi in from and 35 in back if you ride smoothly.

It is just something to experiment with, everone has personal tastes one of my friends runs 20psi front and back on tubes, another runs 50/50.

I go tubeless and do 7/30

I know it is a bit of a general answer.

but to simplify drop the type pressure a bit at a time until the tyre drag and pinch flat then get to much, then go tubeless

4. ## Generally at 185lbs...

you could likely run a bit lower pressure. However where the mud line is on the tires, as noted, is pretty much irrelevant. As noted by the others, there is no set rule for tire pressures. It all depends on riding style, tire construction, rider weight, terrain, tire volume, etc. All you can do is experiment and see what works. Drop your pressure 2 to 3 psi at a time and go ride. Once you start getting pinch flats, or the tire becomes unstable i.e. feels like it flexing or squirming around under you, take the pressure back up 2 to 3psi. And don't be affraid to try different pressures front and rear. I've found you can often run a bit lower in the front than in the rear.

Good Dirt

5. Thanks for the replies. Titrating 2 or 3 psi at a time and staggering between front and rear sounds like a good plan.

Tubelessness sounds like the ultimate solution, but if I were to go tubeless, I’d definitely switch to better tires or even UST tires.

In either case, I’d be adding weight because the Jones XR are 490 grams. My bike is heavy enough as it is.

Thanks again.

6. Ghetto is the way to go with tubeless, cheaper, lighter and better than UST.
Make that a lot cheaper.

7. Originally Posted by Squash
you could likely run a bit lower pressure. However where the mud line is on the tires, as noted, is pretty much irrelevant. As noted by the others, there is no set rule for tire pressures. It all depends on riding style, tire construction, rider weight, terrain, tire volume, etc. All you can do is experiment and see what works. Drop your pressure 2 to 3 psi at a time and go ride. Once you start getting pinch flats, or the tire becomes unstable i.e. feels like it flexing or squirming around under you, take the pressure back up 2 to 3psi. And don't be affraid to try different pressures front and rear. I've found you can often run a bit lower in the front than in the rear.

Good Dirt

Any pressure estimate thrown out there without knowing AT LEAST your weight and your tire size is pretty useless. Terrain also plays a roll. The above method is the way to find out for yourself. For me, I'm 185 with gear, and run 23/30 (F/R) with 2.4/2.3 tires.

8. i ride kenda sb8's 40psi. i rode them at 30ish for a bit but 2nd ride under 40psi i got a pinch flat and it ruined my day. i stay right around 40 and havent had a problem in months.

9. You run 7 PSI in the front??

Originally Posted by CaveGiant
The mud coverage is irelevant, it just means you can lean your bike a lot further and still have traction.

Tyre pressure depends on how hard you rider, what type of terrain and your weight.

You can probably get away with about 20psi in from and 35 in back if you ride smoothly.

It is just something to experiment with, everone has personal tastes one of my friends runs 20psi front and back on tubes, another runs 50/50.

I go tubeless and do 7/30

I know it is a bit of a general answer.

but to simplify drop the type pressure a bit at a time until the tyre drag and pinch flat then get to much, then go tubeless

10. I weigh 200 or a hair more geared up and I am running 25 front and 27 rear. I ride a lot of roots, some rocks, and quite a few logs in varied single track surfaces. I don't always take a good line, especially when tired I will just bash over obstacles. No pinch flat issues or squirmy tires for me. Traction is so vastly improved over 35 or more it isn't funny, and the tires are faster at lower pressure. You couldn't PAY me to go back to high pressures in my tires.

11. Originally Posted by HSMITH
I weigh 200 or a hair more geared up and I am running 25 front and 27 rear. I ride a lot of roots, some rocks, and quite a few logs in varied single track surfaces. I don't always take a good line, especially when tired I will just bash over obstacles. No pinch flat issues or squirmy tires for me. Traction is so vastly improved over 35 or more it isn't funny, and the tires are faster at lower pressure. You couldn't PAY me to go back to high pressures in my tires.
I haven't done any kind of random sampling analysis, but I think running <30 psi non-tubeless with a 200 lbs load without pinch flats or squirmy tires is unusual. Maybe you are using a much better tire?

12. Originally Posted by sponger
I haven't done any kind of random sampling analysis, but I think running <30 psi non-tubeless with a 200 lbs load without pinch flats or squirmy tires is unusual. Maybe you are using a much better tire?
I'm 190 with gear (used to be ~200) and I have no problems getting away with low-mid 20's in the front. I run ~23 psi front with something like a Big Betty or Rubber Queen, ~26 with something like a 2.35 Nevegal/BG or 2.3 Timber wolf. All with tubes.

But for the rear, 30 psi is about as low as I go with something like an Ardent 2.25, Mountain King 2.4, or similar size. With a higher volume tire (like a Big Betty or Rubber Queen) I could go a little lower.

13. You do have to just sample for yourself. This is one place where I found it is worth spending for a good set of tires. I run the Kenda Nevegals F/R, I weigh 255 lbs., and run 35 psi both F/R. Lowest I will go is 32 psi in both (on a smoother trail), and have never had a pinch flat with them. With the tire itself being "better made", it gives a little with lower pressure to make a softer ride, but is strong enough to not give all the way and create a pinch. Of course that is my somewhat educated opinion, and opinions are like butt-holes.....everyone has one and they all stink.

14. I am running WTB MutanoRaptor Race 2.4 DNA compound tires. It is a very light casing and more like a big 2.25 than a true 2.4. In all but mud the tire is simply great. It doesn't squirm, haven't had a pinch flat yet with about 300 miles on them now. I haven't gotten around to converting them to tubeless, and as well as they are working it is pretty low on my priority list. I think riding style and terrain has a lot to do with it and encourage everyone to try lower pressures.

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