• 06-11-2020
    6BQ5
    80mm vs 90mm vs 100mm rims on tire profile
    How do wider / narrower rims change the effective tire profile in terms of tire height and tire width?

    When would someone choose one rim width over another?

    -=- Boris
  • 06-11-2020
    Jayem
    Yeah, for sure. When the tire is very wide, like a true 5", it's best on wider rims, like 90 or 100mm. You start to lose sidewall support and the proper grip of the tread when you are running too narrow. I run some D5s on narrow 65mm trims on my "light" fatbike and they lose a ton of grip and stability as compared to running them on 90mm rims. Likewise, running 4" tires on my 90mm rims results in a square low-profile that leaves the rims much more exposed with little tire-volume to work with air pressure. 80 is usually a fairly good all-around, although I'd lean towards 90 as that all-around for winter riding. When you need max float in the winter, you go around 100 or slightly more. But again, it'll limit your tire selection.

    It's not like your bike will explode from using tires mis-matched to the rims, but handling and other things are compromised.
  • 06-11-2020
    timsmcm
    Jayem how do you like 4 inch tires on 65mm rims x 27.5?
  • 06-11-2020
    RockyJo1
    I think my Snowshoe XL went from 113 mm to 121 mm going from a 65 mm to 94 mm. Also a much flatter tire.
  • 06-11-2020
    6BQ5
    Going to a 94mm rim made your Snowshoe XL true to size! You're right at 4.8". :)

    -=- Boris
  • 06-11-2020
    Jayem
    Quote:

    Originally Posted by timsmcm View Post
    Jayem how do you like 4 inch tires on 65mm rims x 27.5?

    I'm not on 27.5 yet, but I plan to build some up soon. Based on my 26 experience, I think I'll need around 80mm rims. 65 too narrow for 4" IME.
  • 06-12-2020
    Flying_Scotsman
    Nifty chart to show you in numbers.... Surly do one too....

    https://45nrth.com/files/media/16437...o_Chart_VF.pdf
  • 06-12-2020
    BansheeRune
    Quote:

    Originally Posted by Jayem View Post
    I'm not on 27.5 yet, but I plan to build some up soon. Based on my 26 experience, I think I'll need around 80mm rims. 65 too narrow for 4" IME.

    Heya Jayem! I have 27.5 x 4 Van Helgas on 70's which provides a very nice rim/tire ratio. Blizzerk 70's are i64 and it gives a nice profile.
    The one thing I have hated is stupid narrow rims with stupid fat tires cause it just sucks to have no choice but to overinflate my tires.
    And your previous post is spot on...
  • 06-12-2020
    Jayem
    Quote:

    Originally Posted by BansheeRune View Post
    Heya Jayem! I have 27.5 x 4 Van Helgas on 70's which provides a very nice rim/tire ratio. Blizzerk 70's are i64 and it gives a nice profile.
    The one thing I have hated is stupid narrow rims with stupid fat tires cause it just sucks to have no choice but to overinflate my tires.
    And your previous post is spot on...

    Yeah, I'm concerned about the sidewall support more than anything. Too narrow and you just can't ride as aggressively in the turns due to this IME. I know there are a few in the 70mm range. I think 70mm is "ok" for 26 if you are never going past 4", but the dynamics may be different for 27.5, so I'm not trying to prejudge. It's like Goldilocks, rim too narrow and no sidewall support and turning sucks, too wide and you flatten the profile, expose the rim and also lose handling.
  • 06-13-2020
    BansheeRune
    Quote:

    Originally Posted by Jayem View Post
    Yeah, I'm concerned about the sidewall support more than anything. Too narrow and you just can't ride as aggressively in the turns due to this IME. I know there are a few in the 70mm range. I think 70mm is "ok" for 26 if you are never going past 4", but the dynamics may be different for 27.5, so I'm not trying to prejudge. It's like Goldilocks, rim too narrow and no sidewall support and turning sucks, too wide and you flatten the profile, expose the rim and also lose handling.

    Agreed. I'm limited on tire clearance with a Sergeant V3. It will be a mid-fat full time. When it comes to 4.5/4.6, I would go with more rim. Van Helga is perhaps, the widest of the 4.0's it seems.
    I really hated the super narrow rims of the 90's with a 2.3 since tire pressure had to be maxed and tire profile was rubbish.