Widest tires on OEM's

millhouse said:

Like I said before, on a stock 17X8" oem wheel, the machining tolerances are
+- .02". Then only way you have a wheel that is larger than published is if you have either a knockoff that is not oem, or bought them from someone who had them widened. Read my above post for the proper way to measure a rim width.

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So are you telling me that the calipers used to measure a rim, the ones that every tire store uses, are not measuring correctly? I find that hard to swallow. My rims are OEM, car was purchased brand-new, and I have not, nor has anyone else, had them widened. All I can do is tell ya what I have experienced, personally, and see with my own eyes everyday. The 275/40's work just fine, despite all the rhetoric bounced around concerning engineers, machine tolerances, etc. Like I said before, I ride them everyday and anyone is welcome to stop by good ole St. Louis to see them. (But only by appointment. lol)

03gtstangguy said:

So are you telling me that the calipers used to measure a rim, the ones that every tire store uses, are not measuring correctly? I find that hard to swallow. My rims are OEM, car was purchased brand-new, and I have not, nor has anyone else, had them widened. All I can do is tell ya what I have experienced, personally, and see with my own eyes everyday. The 275/40's work just fine, despite all the rhetoric bounced around concerning engineers, machine tolerances, etc. Like I said before, I ride them everyday and anyone is welcome to stop by good ole St. Louis to see them. (But only by appointment. lol)

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Well what can I say, perhaps they are using them wrong or measuring to the wrong feature.

Your oem rims are +- .02" on the machining tolerance for the rim width...plain and simple. They are no wider than any other oem 8" wide wheel.

You may ask how I know this...well I design wheel's and tooling for a living. I deal with these things every day. We did the 99-01 cobra wheels, the 99 gt wheels as well as wheels for numerious other oem applications.

Now, with that being said, perhaps you overlooked the fact that I myself am running 275 width tires on 8" wide rims...but it is against the tire and rim association to do so, so I can not honestly say that it is safe to do the same.

Just go with 255's all the way around and be done with it. This way you can rotate, and you will safely have a tire mounted to your stock rims. Widest recommended on 8" wheel is 255, plain and simple. Can you fit 275, yes. Is it
recommended, no. Is it safe, probably not. Will something happen, hopefully not. Do the smart thing.

rjstaaf said:

....<snip>...Yes, mounting a tire designed for a wider rim can cause the edges to wear faster than the center.

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I agree with everything Bob says about following Mfgr's recommendations except the above quote. Putting a too wide tire on a narrow rim will pull the sidewalls in. This causes the outer edges of the tread to roll up off the road. In turn you lose contact patch and reduce traction. Sorry Bob the outer edges won't wear faster. They aren't touching the ground, at least not until the center of the tire wears to were the outer edges will start to touch.

Yes, you can mount a too wide tire on a narrow rim and it looks like it is making full contact when setting in the driveway, but... centrifical force causes tires grow when they are spinning so the edges of the tread won't make contact. Go too wide and the bead will roll off the rim. At best you lose contact patch and the tire will wear unevenly.