[ttw6909]

hello all!
just got a 718 cayman S with 20 inch wheels. i am looking to downgrade it to 19 inches for winter tires
i am currently looking at 19 Inch rims with following specs
19X8.5 fronts with 50 offset to use with tires size 235/40 R19
19X9.5 fronts with 50 offset with tire size 265/40 R19
all the experts out there do you think i will have any fitment issue?
thank you

 

[DriveInHouston]

From the horse's mouth:

http://www.porscheownersmanuals.com/2017-718-cayman-manual/17/318/Wheels-and-tires

Porsche specifies 8" rims in the front and 10" in the rear with an offset of 57 and 45 respectively. Given the narrower rim in the rear, I think it is almost a wash. I'd think the fronts too. I hope someone has mounted such a tire/wheel combination to give you first hand comments.

 

[don]

There are lots of sites but I use https://www.1010tires.com/Tools/Wheel-Offset-Calculator# or https://www.willtheyfit.com/ to check fitment.

As noted above standard 718 Carrera S wheels are Front: 8 J x 20 ET 57, Rear: 10 J x 20 ET 45.

So your new wheels will give you

Front: 1 mm more inner clearance and 13 mm less outer clearance .
Rear: 1 mm more inner clearance and 11 mm more outer clearance.

It is a bit of an odd configuration performance wise but from what other 718 people have used I think both these wheels/tires will fit fine. Although I'd go 8" on the front if you can find it and ET 35 or 40 on your 9.5" rear wheel if you can get it.

I know with the smaller wheels you just have to watch out for the lower tie rod clearance. I think on the rear.