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Over sized tires on stock rims

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by FosgateElite, Apr 17, 2009.

  1. FosgateElite

    FosgateElite New Member

    So I have the 245/70-17 stock rims and tires at the moment. I don't really have the cash right now to get new wheels too (plus i haven't seen any i really like). So I want to put some larger AT tires on the rims I have but i don't really understand the technical details of tire sizes and what can fit on what.
    Not only do I want them taller, but I want them wider as well. Hence the 275 request below.

    Is it possible to put a 275/xx-17 tire on my 245/70-17 rim?

    Im not really sure how to calulate the XX.
    Last edited by a moderator: Apr 17, 2009
  2. MrShorty

    MrShorty Moderator Staff Member 1000 Posts 100 Posts

    Do you know how wide your rims are (clean the inside of the wheel and see if it is stamped into the metal somewhere).

    Unless they put really skinny rims on there (stock in those cases I've looked at have been 6.5 or 7 inches), 275 mm wide should fit just fine.

    As far as figuring out the aspect ratio (xx), here's what the numbers mean (put this into your favorite search engine, this information is all over the internet):

    275: nominal tread width in mm (TW)
    75: aspect ratio (AR), basically sidewall height divided by tread width (as a per cent).
    17: rim diameter. (RD)

    So to figure out what aspect ratio you want: determine what overall diameter (OD) you want, then solve the following equation for AR:

    2*TW*AR/100+RD=OD
  3. Bluewater

    Bluewater New Member

  4. FosgateElite

    FosgateElite New Member


    Awsome site. Thanks!

    I ended up deciding on some 18" rims anyways. :)
  5. Bluewater

    Bluewater New Member

    site

    They sure make it easy..

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