Need some help with track day tire sizes--987

[MikenOH]

on the 987, the front -rear sizes must be within a +5%-5% window or the ABS acts up. So if your front has an OD of 25" your rear can't be any larger than 26.25".

In my case the tire maker has a 245-35/18 tires which will work well with the 275-35/18 on the rear. Both OD's will be about .6" smaller than stock but will be in the 5% range and the F/R OD differential will be properly maintained.

Nothing like a set of free track tires, especially if they fit..