Sprockett

chriswd62

It could be ordered with 20x8.5 and 20x10, but the + 1"/ - 1" rule allows you to use the 19x8.5/10 combo. Unfortunately, there are no off-the-shelf wheels that I know of that meet the offset requirements of the rules, which is why I ordered custom Forgeline wheels for my 981. These will be for sale shortly, btw.

Check out this link for the specs.

https://www.suncoastparts.com/product/981TECHNOS.html

Sprockett

chriswd62

Edit: No. It was not. The GTS was only offered with 20" wheel options, if I remember correctly. Can anyone else confirm? The base and the S allowed 19" wheels, but they were only 19x8/9.5.

Sprockett

chriswd62

No. The GTS was not available with anything other than 20" wheels. The S came standard with 19", but could be optioned with 20". The base came standard with 18", but could be optioned with either 19" or 20" wheels. Either way, the only 19" width options for the 981 was 19x8/9.5. There were never any 19x8.5/10 combinations available for any version of the 981.


Here are some links to the 981 Cayman brochures:

http://www.auto-brochures.com/makes/Porsche/Cayman/Porsche_US%20Cayman-GTS_2014.pdf

http://www.auto-brochures.com/makes/Porsche/Cayman/Porsche_US%20Cayman_2014.pdf

911C4GTS

Let me know if you plan to sell your forgelines. I might be interested.

Scooby921

Late to the party, but this is correct. I built and ordered a 981 GTS and 20" wheels were the only option. I remember being disappointed because Michigan roads suck and I wanted more sidewall to protect the wheels. There were several styles and they were either 8" front and 9.5" rear or 8.5" front and 10" rear widths. I wasn't aware that the OEM 19" wheel options on the S were all narrower. With the 20" options being available as an upgrade on the S it seems a 19x8.5 and 19x10 combination is the only option if you want the widest possible wheels on a 981 S or GTS in street class. 255/35R19 and 285/55R19 RE71R's exist and should clear the fender and suspension within the ±7 allowance on offset.

Sprockett

Is there a reason 265/305 won't fit?

Scooby921

Assuming the tires clear the spring on the inside I think fender rubbing will be an issue on the outside. To make them fit you'll need the full 7mm allowance on the wheel offset. Then you're adding another 15mm of tire on the outboard side in the front and 20mm in the rear. No OE suspension is stiff enough to prevent a few inches of compression when you're cornering and the body rolls; plus every sportier OE suspension option removes another 10mm of ride height. You're also camber limited in the front and can't rely on the added negative camber to help the tire clear under compression.

Also, putting a 265 on an 8.5" wheel and a 305 on a 10" wheel might be possible, but I don't know if you're going to see a significant improvement in performance over the same tires in a 255/285 setup. The wider setup is too wide for the wheels and you'll end up with a less than nominal tire shape / profile once mounted. Instead of vertical sidewalls and more square shoulders you'll have a rounded shape. The tire may squirm a bit while cornering and the non-vertical sidewalls will have an impact on steering feel and response. Coupled with added weight I don't think it makes sense.

235/265 on 8.5" and 10" wheels fits like /```````\
255/285 on 8.5" and 10" wheels fits like |````````|
265/305 on 8.5" and 10" wheels fits like \`````````/

Sprockett

Thanks for the thoughts. I'll report back with a conclusive answer when I try it.

PedalFaster

The B Street C5 Corvettes run 8.5"-wide wheels as well. Some people prefer 255s, some people prefer 275s, and test results have been inconclusive -- some found the 255s faster, some found the 275s faster. I didn't find a repeatable time difference in my own back-to-back testing, but I ended up running 275s for heat capacity reasons (RE-71s get greasy if they get too hot, and Corvettes have a 5.7 L heater sitting right beside the front wheels).

Given that, I think testing different sizes on a 981 would be a reasonable idea, budget and fitment allowing.

chriswd62

Yes. They will be for sale in the late winter, when my replacement wheels come in. PM me if you're still interested.

911C4GTS

It says you aren't accepting any private messages.

chriswd62

Should be fixed now. Sorry.