993GT

Got exciting news today, Tirerack will now be carrying the RT615K

my favourite all-round performance tire in our 315 sizes

Kevinmacd

Doesnt help me need 295-30-18

Road King

For non track use I'm having great success with Falken's Azenis FK453s...they come in stock 996T sizes.

Carlo_Carrera

You can pair 315s with 245/40s.

James88

I believe this a better match for our awd than 235/40/18 & 315/30/18

jeanmarcboilard

+1

split71

Dammit! Just put a set of Pirelli's on as that was the only tire I could find in matching AWD sizes stated above.

xmaciek82x

Yup. Much better match then 245/40.

Are you guys running 315/30-18 on 11" wheel?

The RT615K is a mean looking tire!

James88

245/40/18 & 315/30/18 is a better match for awd than 235/40/18 & 315/30/18, front tire needs to be a bit taller than the rear.

xmaciek82x

OK, the last debate I read on this topic was that the rear and fronts just need to be within certain % from each other, I believe it is 3%. Didn't really matter which one was smaller. The Porsche winter recommended tire size make the front smaller then rears. The summer recommended size make the rear smaller.

But having said that, when I did the calculations for 245/40/18 & 315/30/18 and 235/40/18 & 315/30/18 I completely forgot to pay attention to which one is taller. I change what I originally said and would go with the sizes that make the rears slightly smaller like the summer recommended sizes.

"02996ttx50

for awd i am fairly certain the 3% differential ratio btw front to rear is correct to not cause damage to the front differential by overheating it but i've always heard said that the REAR is the tire that if at all needs to be taller. not the front. i'm rwd so i have a bit more latitude if not sizing choices, but at least i don't get those dreaded cels when matching old X new tires. 235/40/18 X 315/30 still seems optimal for me handling wise. i've never felt the need to mess with success or stray too far away from porsche's recommendations. aside from the rwd part, of course.

but now i'm confused. is everyone certain that it's the FRONT that should be taller?! i'm a bit skeptical of that somehow.

Road King

Yes, front is taller from the factory on all AWD 996 Turbos

225/40/18 approx 25.1" tall
295/30/18 approx 24.9"

Hence the front turns slower / less revs per mile.

James88

Phound recommended 245 over 235 for awd, fronts need to be a bit taller like factory different diameter
And this is my dilemma as l can't find matching tires in my prefered PS2/ PSS

993GT

both 235/40 and 245/40-18 front tires are completely safe and acceptable with a 315/30-18 rear

James88

Dont you think the slightly taller front biased would be a better match?