Quote:
Originally Posted by cooltoy
Why would it do that? The diameter does not change. Is it the wider rim that would throw the speedometer off?
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The OD (Overall Diameter) of your tire changes depending on the brand and aspect ratio.
A 275/35/19 tire does not have the same OD as a 285/35/19 tire does. The inside diameter is the same because it needs to fit a 19 inch wheel, but the OD changes.
Look here:
Bridgestone*Potenza RE050A
The OD of the stock 275/35/19 Potenza RE050A is 26.5".
Now here:
Yokohama*ADVAN Sport
The OD of the stock NISMO 285/35/19 Yokohama Advan Sports are 26.9".
That is why, generally, for every 20 mm of width that you go up in a tire, you need to go down a level in aspect ratio. For example, I should be able to run a 305/
30/19 on my car and still be pretty close to the factory OD (depending on tire manufacturer).