Rear Tire size question

[Lew]

You are talking about tire width here. 245 Millimeters. A difference of 10 Millimeters in width from the 255's. I don't see a problem.

[maytag]

Originally Posted by Lew

You are talking about tire width here. 245 Millimeters. A difference of 10 Millimeters in width from the 255's. I don't see a problem.

you're also talking about sidewall section though, not just width.

I assume you understand this, and were making a comment that the difference is negligible. ?

For any who may NOT understand it, the 2nd set of numbers (in this case, /40/) is what's called the "Aspect Ratio". A ratio is such because it's "relative" to another number.

So, for instance, a 225/40/ has the same aspect ratio as a 255/40, but the sidewall height (and therefore the circumference of the tire) is dramatically different.

However: in the case of a 245/40 vs a 255/40; in my experience, you'll see a larger difference in circumference between brands of tires than you will in that size difference.

here:

245/40-17 Sidewall=3.9", Radius = 12.4", Diameter =24.7", Circumference = 77.6", Revolutions/mile = 816
255/40-17 Sidewall=4.0", Radius = 12.5", Diameter =25.0", Circumference = 78.6", Revolutions/mile = 806
a difference of 1.3%

[Lacostas]

Thanks for the input guys. Well it seems that I won’t use my friends tires. The only tires that I can find now (ready to buy and install without ordering etc) are the PS2. But for the front I’ll keep my Bridgestone Potenza N4.

Any implications on this? I know it’s supposed not to mix tires but I always wanted PS2. Front Bridgestone tires are still good for a year ..