BlueJay73

Posting this in this forum and the Racing/DE forum.

Re: The question of whether nonGT3 997's can run NT01 245/40/18 front and 315/30/18 rear without throwing codes or going into limp mode, due to the rear O.D. being smaller than the front O.D. (997 GT3's can turn off electrical nannies, nonGT3 997's always have them running in background).

I borrowed a fellow Rennlister's NT01's off his GT3 (in the sizes stated above). The rears were worn, making the O.D. issue even worse. Before I put them on, I stood the rear NT01 tire next to my NT555RII 305/35/18 (the proper size with the correct O.D.). It did not look promising. The NT01 was a solid INCH shorter than the 555RII. I put them on for one 25 minute track session on a very technical track with one long straight. Hit 122mph on the straight. Drove them a bit harder than I told him I would. Sorry David; I told you I'd buy you lunch...

Result: NO CODES, no limp mode, no nothing.
Had PSM on, had PSM off; nothing. Went fast, went slow, sudden hard braking, sudden hard accelerating, aggressive turns, RPM's in the 4000 to 7000 range, tried everything. NO CODES.

They also gripped a lot better than the 555RII's. As soon as I use up the 555RII's, I'm getting 315/30/18 01's. However, Nitto, pleeeeeeeease make a 305/35 or a 315/35 !!!!!

ps: This is not a guarantee that this will work for everybody. This was my test on my car.
Jim

MagnusB

For reference I use 275/35/18 front and 315/30/18.
No codes.
The front tires do rub the spring perches sometimes.

And the 275/35 and 245/40 tires have the same diameter, 25.55.

BlueJay73

Do you have a GT3?
Is your car the same front body style (fenders and wheel wells) as a regular 997?
Did you have to make any modifications to fit the 275's (roll fender lips)?
Does rubbing spring perches cause any problems; wearing out tires, damaging spring perches?
I'd love to fit 275's up front to combat understeer, but didn't think that was possible w/o mods.
Thanks

MagnusB

It'a a 2007 997S with PASM and aero kit.

It does wear a bit on the tires but not much as it is such a smooth surface on the perch, or you can see a more rugged area on the tire there.
It doesn't hit the fender at all.
It doesn't bother me much when it happens but is of course not ideal.
Possibly it could be solved with a spacer.

DC640

what wheel are you using and width?

7500rpm

Bluejay73, 275s to counter understeer? I run 245s in front for my 06 C2S and I only have problem with my 305 rear oversteering. Since Porsche fitted only 235 as standard for the front, you (and MagnusB) seem extreme fitting 275s. You might want to try some camber changes up front instead of wider tires. Good to learn there's no rubbing problem with 315s in our NB cars. I might need to step up to 315 next. I can definitely go faster with less over steer.

DC640

I have tire dilema post going on 997 gt3 section. Since OP has some time to experiment on 997 NB, i thought i would ask here also.

I have 997.2 gt3.. not sure if nannies are more sensitive than non-gt3 when leaving them on. I know you can completely turn it off on gt3 but I leave them on for my training =)


I thought of using R888 but people hate them here. But my rational is that it is better than what i run now - MPSS. Ill wait until NT01 releases 305/35/18 - they are finally making them.

BlueJay73

You state "they are finally making them."
Do you know that they ARE making them?? or are you saying if/when they make them?
If you know that they are actually going to make them, where/when did you find this out? That would be great news!

Also, I never had any problems with the R888's. They wore well, didn't split the tread, gripped well, didn't HC out prematurely. I just wanted an option to the R888's with the NT 01's. I ran lower pressures than a lot of people do, I think. Also, my car does have GT3 LCA's for more neg. camber, maybe that is helping them.

ckiesz

Nitto has a "Coming Soon" in the NT01 spec section on their website for a 305/35zr18 : ). I am also waiting...