CaymanDave

Currently have 20" if I go down to 18" or 19" do you have to get anything programmed, I come from the jeep world where you have to program tire size to keep the speedo and odometer correct.
Will Carrera S 991 wheels fit or is the offset different?
Thanks,
Dave

ICNU

You will need to reset the TPMS settings to the new wheel size. This is a simple 30 second process and done in the TPMS menu using the dash stalk. The offset between the 911 and Cayman wheels are not the same. Doesn't mean that they couldn't "possibly" be made to fit, but it would all depend on the specific wheel/tire size and if there were appropriate spacers available

981KMAN

Hey Cayman Dave, I have a 2015 base Cayman with the OEM 18" rims. Love them.

As stated above you only need to tell the Tire Pressure Monitor what rim size you have as this changes the low pressure alarm levels. Otherwise the OEM Tire Diameters are all approximately the same whether the rim size is 18, 19 or 20 inches.... From https://tiresize.com/calculator/ for the rear tires...

265/45-18 tire diameter = 27.39"
265/40-19 tire diameter = 27.35"
265/35-20 tire diameter = 27.30"