315/30/18 on a 997s
 

Hey Fellas,

It looks like the GT3 folk run these quite often, so I'd assume they would fit a 997s too? I've exhausted the search function and can't seem to find a definitive answer. This would primarily be a street car with an occasional track day.

Thanks!

Ryan

OEM is 26.2" tall. This is only 25.4".

It would work on a 996, but not on a 997.

Hmmm? Maybe I'm missing something here but the 997S runs (rear) 295/30R19 stock which comes out to 25.97in. 315/30/18 comes out to 25.44in like you stated. That should be within tolerances.

http://www.1010tires.com/Tools/Tire-...ismetric=False

Correct me if I'm wrong here...

OEM rears in both Pirelli, Bridgestone, and Michelin are at least 26" tall.

295/30R19 MI PILOT SP PS2 N2 = 26"
295/30R19 BS PZ RE050 A N1 XL = 26.1"
295/30R19 PI PZERO N2 XL = 26"

305/30R19 PI PZERO N2 XL = 26.3"
305/30R19 MI PLT SP PS2 N2 XL = 26.3"
305/30R19 BS POZ RE050A N1 XL = 26.3"

Ahh ok..so you're saying the variance between the 305/30R19 and the 315/30R18 is too great. What's the acceptable variance? According to 1010tires you're still within their recommended 3% diameter variance. Is that a bad recommendation?

I guess the other thing to consider here is if the vehicle is a 4S or not. The 4S comes stock with 305s and the S comes stock with 295. If the tolerances are that tight we'll want to make sure we know which tire we're comparing. This would assume that the car is setup differently from the factory for the 4S and S models. If that's not the case then which tire size are we supposed to be using for a baseline?

Thoughts?

I'd stay 3-4% myself, AWD or not. I have had customers that have done same OD sizing F/R on the 997 that have reported PASM issues and the car not feeling planted properly, and there HAS been issues of AWD damage on 997 Turbos when using the same OD sizing.

On the 996 you want to be the same size F/R. On a 997 you should be .5-.7" taller in back.

A friend of mine put my 315/30-18 nt01 rears on his 997s and took them on track for a few sessions and had no issues whatsoever. They were pretty well worn at the time also but I don't know if he pushed his driving or not. YMMV

What was he running on the front?

245/40-18 nt01 on 9" wheels off of my car. 1.1 inch taller front from Nitto info.

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