dave_k

Bridgestone Potenzas.

To clarify, I understand about speedometer error. I'm aiming to go down an inch in wheel size and up in tire profile to match, so the wheel circumference stays about the same.

Thanks. So far, the dealer is not interested in a swap. They sold me the car at an "internet price" and seem to want to be done with it. But, I'll keep nudging. Is it unwise to go to a 45 profile on an 18" rim with this car? Or a 50 with a 17" rim? I understand the speedometer problem. It's the wheelwell and computer part that's a concern.

Thanks, Edward. My IS 250 is a standard model with the navigation system, not a sport model (F?). So, I think I'm back to the rim and tire size. I do know that if I add more air between me and the road (higher profile), the ride will be softer. I did it with my old SC 300 by 10 or 15 profile units. So, it's the limitations of wheelwell and computers on the IS that concern me.

Just bought a used 2011 IS 250 - Nav, and the 18"X40 profile tires are too rough. Can I avoid buying new rims and just go to a 18"X45 or 18"X50 without hitting the wheelwell or messing up the trac control/ABS computers? I know the speedometer will be off a little with a different circumference. The one Lexus service manager I spoke to was very concerned about the effect on the trac control and ABS. Or do I have to go with new rims ($$$!) and use the 17"X45's that come with the non-Nav model? Or maybe do 17"X50's? Many thanks!