There's three things that are important when talking about sizes. First of all, if the car has anti-lock brakes, all the tires must have the same outer circumference, unless it came with larger tires in the rear. In that case it's almost mandatory to stick with the original sizes to keep the ratios correct. The computer will detect wheels turning at different speeds, set a diagnostic fault code, turn on the yellow warning light, and turn the system off.
As a suspension and alignment specialist, what's important from my perspective is "scrub radius". I can explain it if you want me to, but it has a major affect on handling, braking, and cornering. What changes scrub radius from what was designed into the car is altering the diameter of the tires' tread, and installing wider wheels or wheels with a deeper offset. There is no such thing as improving scrub radius. It is already as good as it can be and any modifications will just make it worse. Chrysler has this perfected better than almost any other manufacturer.
You can be very sure lawyers and insurance investigators know what scrub radius is and they will use it to their advantage when their client ran the red light and caused a crash. They will shift part of the blame onto you because you were less able to avoid the crash, and they will be right.
You didn't bring this up, but altering the suspension's ride height can also land you in court. I shudder every time I see a raised truck or a car dragging on the ground. Lawyers love to find any kind of modifications like that. I've had many older muscle cars, and the ones I have now are exactly at the specified height, and they have the factory wheels with the proper tire sizes. Standard wheels look better anyway. I don't see the fascination with big wheels with nothing for tire sidewalls. They look silly. Also, there's no sidewall to flex when you hit a bump. If you're concerned with ride quality, you're going to be very disappointed if you go to low profile tires. Think of them as driving on wooden wheels with no rubber.
Thursday, December 12th, 2013 AT 6:26 PM