theprezz

Hi guys,

I was wondering: If I put 325/30R21 on my Porsche Turbo 991, will it cause any issue with the AWD system as it's bigger than the original 305-30-20?

325/30R21 are the OEM on the GT3 RS, but it's a RWD, I just wanted to make sure.

Thanks!

CDinSing

There may be a couple of issues fitting them. They are .8" wider and 1.7" larger diameter. The rotational difference limit front to back for the AWD used to be 3%, honestly not sure what the 991 limit is but this a 6.6% difference. Hopefully someone can give you advice on whether that will not hurt the AWD. Beyond that I remember reading an interview with AP about the development of the RS and he said they could not fit the rear tires to the turbo shell. They had to develop a new narrower inner fender liner. Since there are no intercoolers in the RS they could do that.

Nanook

There was a recent post where someone had just done this tire change on the rear with no issues although they also changed the fronts to 245 I think...I did a quick look but couldn't find..sorry..poke around on the two forums

Nanook

https://rennlist.com/forums/parts-ma...h-buttons.html

Karl911

you have to kept the ratio f/r diameters about the same. I have been running 265/35/20 FR and 325/30/20 R MSC2 for over a year, on stock wheels, 32/36 psi for daily driving and they are absolutely fantastic.

CDinSing

This option makes more sense as it increases the size similar f/r giving more grip on the same wheels but doesn't add an inch wheel diameter (21) in the rear like the RS option.

Karl911

265/325 with H&R lowering springs

francisluu

With the stock ride height, does this fill the wheel well gaps a bit more with the wider and (slightly) taller tire?

This set up would also be an improvement for on-track grip as well?

Randyc151

I've done the math, and I'm going to try this with my next set of tires. The 325 are also much cheaper at tire rack right now than the 305.

FBA

I'm running 335/30/20 and 265/ 35/20's Rears are mounted on a 13" rims and fronts on 10.5". No issues and with the techart lowering springs, I still get back the ride comfort lost on the lower springs, because of the higher profile on the tires.

No wheel gap at all - but she scrapes in front if I'm not careful. Fatter / taller rears with lowering makes front sit lower. I have like 2" of spoiler clearance, but it looks cool as hell! Really no issues...

GarbageMan

No offense, but as OCPD as I am, I'd have the Grand Mal Seizure of the century if mine rubbed. I think I'm staying with stock sizes (in the interest of my own health)... YMMV...

Karl911

I am lowered and they only rub a little on the inner plastic wheel well liner on lock to lock turn in !

GrandLaker

Does Michelin not make the Super Sports in 325/30/20? All I can find are the SC2's.