Comparing 986 and 987 tire sizes

[stephen wilson]

Yes, you do have to be carefull with relative front/rear diameters. I put 245/40-18's on the front of my 987, whick worked well to reduce understeer, but if I raise the front pressure more than 2 psi , it's makes the PSM kick in all the time.

[stephen wilson]

To your point, I would stick with the 265/40-18 on the 987, there's no reason to go to a 265/35.

As far as the 986, the 265/40's are 1" taller than the OEM tires, I would verify that others have run them without issue. Of course, you could just swap wheels for a while, and do a little "testing" to see if there is any ABS problems. You would probably have to live with the speedo being off.