Chris88

I apologize in advance if this has already been discussed (I'd be surprised if it hasn't), but I could not find anything by searching. I'm about to purchase new Cup 2's for my GT3, and the non Porsche spec version on Tirerack are over $260 cheaper. I contacted Tirerack about this, and they said there'd be nothing wrong with using the non spec tires. Does anyone here have experience using non spec tires (especially the Cup 2's) on their GT cars?

tqevo

It's a different compound and tread pattern if I recall. Mercedes used the ZP Cup2s from the Z06 for their Ring record. I wouldn't put non-Porsche spec Cup2s on my GT car. Different tires? Sure, but the potential savings on the Cup2s aren't worth the risk to me

LexVan

There's no risk.

There is a performance sacrifice.

Will you notice it? Depends.

Chris88

Thanks for the input. The Tirerack rep that I contacted said there would be no difference in the performance of the tire. I do autox my car, so want the best performance possible. I'll do a bit more research before I make a decision.

tqevo

Depending on what organization you run with there are rules against running non-spec tires. For autocross and SCCA rules you'd probably be better off running RE71rs. Yokohama A052s are tad quicker but no sizes available for GT3s

GrantG

I believe the rear tires in N-spec are built wider to fit a 12" rim (more like a 315 or 325 wide tire), while the Non-N tires recommend max 11.5" wide rim for their 305/30/20 tires. So, I'd pay extra and get the N's if it was for myself...

ThEnder

I wonder what Porsche's rationale for speccing a 305 series tire on a (seemingly) non-standard 12" wheel was?

asenna8

It appears the N1 version of the Dunlop Sport Maxx Race 2 has the same width recommendation as the others in that size.

R

evilfij

Chris, check widths. Non-n spec has been a problem for many.

zedcat

A few years ago was having trouble finding N0 cup 2 for my .1GT3, found some non N spec tires from Discount tire online. Talked to a rep and he claimed they were identical to N spec tires and I ordered them . the tires I received had an R code on them which is an Audi spec. I researched the details and found the tread width for the R tire was less than the Porsche N spec. I sent them back.

Chris88

Thanks, the more I look into this, the more I see it's best to stick with N spec tires. The savings doesn't seem worth it.

GrantG

asenna8

FYI:

Pirelli Trofeo R
Continental Extremecontact Sport

GrantG

I think that's just an error on Tirerack's site. The Dunlops in N1 are made for 12" OEM rim (as are Cup2)

GrantG

I think the rationale was to require buyers to use tires that are specifically designed and tested for the GT3 (and maybe a financial relationship exists between Porsche and the tire makers), but they may have inadvertently created an unsafe situation (as many tire places and even dealerships are not aware of the distinctions between N and non-N).