Originally Posted by Duke Togo

Really quick but when you change the tire size with the same width rim it's possible the sidewall height and contact patch are different - also tires arent the same in all sizes it's possible that the different size is causing tramling as well or your old tires may have been stiff from heat cycling and low tread depth would have reduced tread squirm.

Here's a quick graphic that should show a difference in contact patch and sidewall height based on sizing.

Originally Posted by alanpikku

That's interesting. I went from a 245 40 17 to a 255 40 17. Side wall height is the same, but maybe the extra wide tire is messing with it? Maybe i just need to wear it out more?

Originally Posted by jabbarahm

I would assume that if you put the 255s on and you're now bulging over rim width, your sidewalls will naturally allow more flex than if they were fit properly. Also, yes, the sidewall is higher as the 40 is a proportion of the width.

Originally Posted by thielepr

Your wheels and tire width are ok. Just put some miles on the tires. Your tire isn't a bad tire. But next time use a better tire. You have a lot of HP. A better tire will help you put those HP on the street.

Originally Posted by Jim@tirerack

I would also say time will make them better. You can go a couple PSI higher on the rear.