I have a 93 Supra Turbo. The stock wheel/tire sizes are

17x8 w/ 235/45-17
17x9.5 w 255/40-17

I was looking to get new wheels for the car and was considering getting the same width wheels and tires for all four tires. Would this be a bad idea? Would I be adversely affecting my suspension geometry? I'm considering 18x8.5 w/ 235/40-18 or 18x9 w/ 255/35-18.

Would I be better off getting 18x8.5 up front and 18x9 in the rear?

Also, which wheels determine the speed that the odometer is reading? The front or rears?

Steve

I would not recommend going same size tire all around unless the car is driven very conservatively. Why do go same size all around? Wear? If so we may be better off looking at some wear oriented tires available in the correct sizing.

In a RWD car, the rear tire diameter change would create speedometer error.

Thanks for the quick response Cy! I had another related question also.

Is the wheel/tire fitment for the normally aspirated Supra vs. the Supra Turbo different for the '93 model year? I was using the online wheel configurator at tirerack.com and noticed that there were a lot more choices for the NA Supra vs. the Supra Turbo. Many choices were available in 18x8 and 18x9 wheel sizes. I also saw that it was possible to configure Moda R6 wheels as 18x9 both front and rears but running different tire sizes on the fronts vs. the rears. The suggestion was 235/40 on the 18x9 up front and 265/35 on the 18x9 on the rears.

The web is correct, fitment is different Turbo probably has bigger brakes that limit some of the choices.