Another tire question

[shadrach74]

So I've been searching the forums and it seems plenty of folks are running wider than stock tires up front on factory 17s. I was wondering if any one had considered trying to correct the factory "built in" speedo error with slightly larger tires.

My calculations show that 225/55/17 and 265/45/17 (255/45/17 would be close as well) would give me a much more accurate speedo (its conservative by about 4 mph on the highway). Has anyone tried this? Will it have affect ABS function?

[Topless]

On a 986 it might work but the 8% loss of torque from effectively up-gearing would overshadow the benefit of a true speedo for me. Tire choices are also somewhat limited in those sizes. I'll pass.

[ekam]

Very few manufacturer make factory 17" tire sizes let alone the sizes that you listed which I'm fairly positive nobody makes 265/45/17. Part of the reason why I went 18"s.

[stephen wilson]

If you have PSM, making the front taller relative to the rear can cause issues with the traction control.

[shadrach74]

Originally Posted by stephen wilson

If you have PSM, making the front taller relative to the rear can cause issues with the traction control.

Good info to have! However, I specifically sought out a non-PSM car.

[shadrach74]

Originally Posted by ekam

Very few manufacturer make factory 17" tire sizes let alone the sizes that you listed which I'm fairly positive nobody makes 265/45/17. Part of the reason why I went 18"s.

True. I have found a few 265/40/17s that should work. This would only be 1.6% difference in diameter and would bring speedo accuracy to within about 2.5mph.