[mskala914]

Isn't is suspicious that for any of the RE71RS sizes, the specs on Tire Rack are identical to the same RE71R?
Like section width, tread width, diameter, etc. That can't be true. Maybe nobody has measured them yet?

Currently using RE71R 245/40/18+285/30/18. I won't choose those next time as the PSM won't work with such
small rear compared to front.

Mark S.
2014 Cayman S

 

[arthurc604]

Out of curiosity, do you get PSM errors? I know not the same thing, but I've been running 285/30R18 and 265/35R18 (in both RE-71R and RT660) on a 987.1 which should be 10mm shorter than your 245/40R18 with no issues.

 

[mskala914]

Not sure what a PSM 'error' is. With those tires I can get a couple hundred yards and then the car complains, won't let you accelerate without pushing the off button. 987 computer may be slightly different, but note that RE71R 265/35/18 is actually 0.4" smaller diameter than 245/40/18 so it's not surprising that your setup would work where mine isn't. It's not the diameters but the ratio of front to back.