powdrhound

Can anyone enlighten me as to the difference between running a 18x8.5 vs 18x9 front track wheel on a 996tt/GT2? Besides the obvious 1/2" difference in width, are there any performance advantages to the 9" wheel? I know with the 9" you can run a 255 or 265 tire but then you are just adding unsprung weight with a heavier tire and a heavier wheel compared to a 235 or 245 on a 8.5" wheel. I plan on running a 235/40/18 Nitto NT01 which according to Nittos website is ideal for an 8.5" wheel (same goes for a 245/40/18). My guess is a 235 NT01 would be a bit too stretched on a 9". Another issue could be brake clearance but that's not a player with CCW wheels which have plenty of room for the 6pots even with a 8.5". It seems that if a 9" wheel was better then Porsche would have been using it instead of an 8.5". Anyone wanna chime in?

cwlred911

I am running 18x9, 18x11 Fikses on my 6GT3 with Nitto NT01s. Had 235s on the 9s with no problems. Up-sized to 245s recently. The 245s will give you quicker turn-ins (less understeer), and better braking. The only draw back is you will get some rubbing on the fender liners on fuller turns. I am running with -2.8 on the front, FYI. I prefer the 245s.

911SLOW

The wider the better..that and good balance between F&R.

For the track it's ok to deal with minor rubbing.
Besides with the correct offset, camber, not crazy low ride height a 255/35 tire on a 9" wheel will clear 100% as its overall diameter is smaller than the 235/40s.

With 235s again you can benefit from the stretch, especially on softer tires.


Why Porsche didn't do it? Probably because the chance of tire rubbing with stock tires and camber was/is considered unacceptable.. Or because at that time the 8.5 wheels were at large numbers in stock.. Or because this setup fitted the type of handling that they had in mind. : )

Btw there is a nice story about the GT2. In the early days of testing, it had been designed to work with a 295 / 235 combo. And Mr. WR changed the plan and asked for 315s and 12" during a hi speed oversteer incident in the Ring.

powdrhound

OK, thanks. I'm running -2.1 camber on the front and -2.0 in the rear on a RUF Rturbo (AWD). The car is very balanced and oversteer is easily induced with throttle on turn exit of with a touch of trail braking. Because of AWD I'm limited to a 235/315 due to the diameter and the NT01s are virtually identical in this size. I just wasn't sure if the 235 would be too stretched on the 18x9 since my 235 PS2 on 8.5" wheel has a bit of stretch to it. I've seen 245/40/18 NT01s on a 18x9 CCW and they looked like they had a bit of stretch to them also and figured a 235 on a 18x9 would really be stretching it (no pun intended)! You wouldn't happen to have any pics of the 235 NT01s on a 9" by any chance?

cwlred911

Not a good picture. But the 235s are fine with 9s. Perfectly vertical sidewalls. Like SLOW said, you will not have any rubbing issues on the track, just with street driving. You may have trouble finding NT01s in 245s. Nitto is real low in stock the last time I checked. I have 315s in the rear, and the car is really neutral with the sways set 1 from stiff both F and R.

ukrbmw

I would say don't do it cause it'll make you faster!

powdrhound

So you rub on the street with a 235? I only thought 245s had issues.

cwlred911

I only get rubbing during street driving with 245s.

mooty

too many things to explain, but the short version is if you can choose 8.5 vs 9 for 6gt3, take the 9" front 12" rear. even with same rubber. wider rim is better. i run 9.5" up front on 6gt3, but i have rolled fenders and i like the sound of fender rubbing tires. 9" no rubbing

Turn3 Autosport

We always recommend you go with the widest wheel you can fit for the given tire size......

For the 996, GT3, turbo or otherwise, we like a 9.0 front for track work. Some are worried about rubbing etc, but if you spec the wheel correctly you will be fine. The added wheel width will help dial out a wee bit of understeer the cars have built into them, plus allows you some wider rubber choices for the track.

For weight, the general rule in three piece or one piece aftermarket forged wheels is the weight goes up 1.0lb for every inch of additional width. So, in theory, a 9.0 should weight about .5lbs more than a 8.5. But there are other variables such as hub pad height that factor in when one attempts to get the correct offset. So, in theory, you could have a 9.0 wheel that weighs less than a 8.5. All of this to say, the difference is not noticeable...

If we can help you out with wheel choice and pricing, let us know!

Cheers

996FLT6

9 inch front 12 inch back- drives sensational. Mike

Serge944

Sure, 9" is better. But I've seen people make cup cars look stupid with 8.5" stock front wheels. So, it's not something to lose sleep over, really...

Turn3 Autosport

Depends on the offset....Sure, you can make it look silly with 8.0's front and 9.5's rear if the offsets are off. Aesthetics aside, 9.0/11.0 is a great set up on track....

Serge944

Maybe you misunderstood. Stupid in terms of lap times

I run 9/11s myself.

AllanJ

I run 9/11 also because I use any of my sets of wheels for wet or dry track tires. I use 295 for wet and those aren't happy on 12" wheels.