akirasan

Just purchased a set of Nitto NT01s (235/45/18 & 315/30/18) for DE days on my C4S. While looking for temp recommendations I've found numerous threads on different sites talking about ABS concerns and tire diameter. Unfortunately there doesn't seem to be an authoritative answer beyond 4% or less (this set is 3.5%) variance, though a concerning aspect was a discussion of wheel RPM deltas i.e. fronts must turn faster than rears. With these sizes, rears turn 1 RPM more than fronts - am I about to be an unhappy camper?

kouzman

subscribed.

the information will be quite interesting.

wwest

I suspect that when you switch tires if you disconnect the battery for a few minutes the ABS (& TC) ECU will then relearn the "new" F/R ratio. C4S...with the VC you might have a problem, with the new electromagnetic clutch not.

mdrums

Cello on this forum runs these tires on a 997 car and had no issues and in a thread just reported this back to me. On the other hand for years I've been told to NOT run tire sizes where the rear overall diamter is smaller than the front and to keep front to rear with in 4% tollerance. I was told that PSM will intervien more frequently thinking the rear wheels are slipping since they will be turning faster tha the fronts. So with those suggestions from many shops that know the 997 platform well I have always used these 2 sizes when running 18" wheels

245/40/18 & 305/35/18......or 255/35/18 & 315/35/18

So since you along with Cell on this forum are running the Nitto NT01 with the small rear diameter....PLEASE report back here after your DE and let us know your findings.

thanks!