Forum Discussion

DwnSth's avatar
DwnSth
Explorer
Jul 18, 2023

275/70R22.5 vs 295/75R22.5

Currently have Sumitomo 275/70R22.5 which matches the coaches original tire spec. Getting ready to replace but having hard time finding the Sumo's. Looking at Toyo and they do not seem to have the 275's. My shop suggested going to the 295/75R22.5's but I'm concerned about going to the slightly larger tire. Any thoughts or suggestions would be appreciated.
Class A
  • Grit_dog's avatar
    Grit_dog
    Navigator
    Jul 19, 2023
    If you can’t figure out whether they’ll fit fine and aren’t good with losing a little bit of power then stick with the OE size.
    If you look at the sizes the 295s will reduce the distance between the duals by that same 20mm bout 3/4” and will be about 2.5” taller raising your effective gear ratio by about 7%.

    Presume you haven’t verified they’ll fit yet?
  • Bruce_Brown's avatar
    Bruce_Brown
    Moderator
    Jul 19, 2023
    We went from 275/70s to 11R-22.5s.

    The 11Rs are the same height as the 295s, slightly skinnier so they fit our rims. 295s were too wide.

    In our case I always felt we were over geared for the 275s, it just turned too many RPM at highway speeds.

    With the 11Rs it's just about perfect. There hasn't been any downside - none.

    Next year we'll be looking at tires again (age) and we'll definitely be doing the 11Rs again.

    All that said, what engine/transmission combo are you running and what is your highway speeds RPM?

    What we did may not be the best choice for you.
  • DwnSth's avatar
    DwnSth
    Explorer
    Jul 19, 2023
    It's a Freightliner XCR chassis. The build sticker with vin and weights shoes the 275/70R22.5 which is what the current sumitomos are.
  • haddy1's avatar
    haddy1
    Explorer
    Jul 19, 2023
    Pretty sure that the OPs coach is on a FL chassis. Probably came with 275/80r/22.5 tires.
  • ScottG's avatar
    ScottG
    Nomad
    Jul 19, 2023
    4x4van wrote:
    Are you sure you don't have the numbers mixed up? 275/75 and 295/70 are almost the exact same size.


    You might read his post again, he stated 275/70 & 295/75. That's about an inch difference in sidewall height.
  • keepingthelight's avatar
    keepingthelight
    Explorer
    Jul 19, 2023
    I changed over to the 295's. The height is very close to the 275's with a slightly wider foot print. The 295's are easier to find as well. Lots of trucks are running this size now.
    Good luck
  • 4x4van's avatar
    4x4van
    Explorer III
    Jul 18, 2023
    Are you sure you don't have the numbers mixed up? 275/75 and 295/70 are almost the exact same size.
  • ScottG's avatar
    ScottG
    Nomad
    Jul 18, 2023
    You and possibly the rigs ECM are going to hate what that change does to your gearing. That's more than a 10% change in gearing.
    I made a similar change with an "embellished" diesel truck and it still sucked.
  • Blaster_Man's avatar
    Blaster_Man
    Explorer
    Jul 18, 2023
    Plug the numbers for the two tires in here, it will detail the differences:

    https://tiresize.com/comparison/

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