Over sized tires on stock rims

**FosgateElite** · 04-17-2009, 10:12 AM

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.

**MrShorty** · 04-17-2009, 10:30 AM

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