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YOUR RESEARCHOptimal Wheel and tire sizing (for track)
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Run 285
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I almost always used 245/35/18-315/30/18 Hoosiers.
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Suggestion
I'm thinking about what Jim said (about the effective gearing change).
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Suggestion
Changing the height of the rear tires is the same as changing the R&P.
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Suggestion · Original poster
If you're careful with offsets you can do cup car sizing of 9' fronts and 11' some are running 12' rears....no clues on tire sizing there as slicks have no reson to be on my car.
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Well it's friday and I'm bored so why not have some conversation on optimal wheel and tire sizing for a Narrow Body 996 for the track.
The easiest combo to come up with for most of us would be 8' and 10' wheels with 225 or 235 front's and 285 rears. ( I use this setup but would like a bit more front grip...which can probably be achieved through sway tuning. camber changes and or tire/wheel sizing).
If you're careful with offsets you can do cup car sizing of 9' fronts and 11' some are running 12' rears....no clues on tire sizing there as slicks have no reson to be on my car.
More reasonable may be 8.5' fronts and 11' rears like a GT3 has with a 235 / 295 setup...but this should be the same balance as the standard 996 setup only with more rubber all the way around.
One of my bigger thoughts / questions. Is an 11' rear really worth getting? Is the rotational mass worth carrying around for the extra additional grip? Obviously there'a alot of mass over the rear of our cars but with <300 WHP is anything larger than a 10' 285 going to be faster or are you just carrying around excess weight and un-needed traction that's actually slowing you down and causing even more understeer?
Lets hear your opinions.
Andy
Forget 12's. The 11's will work (see NB GT3 wheels). I would advise sticking with the 8's & 10's or 11's. The tire choices for those sizes should be ample.
C.
My wheels are; F 8.5 x 18 ET 45 (this wheel sticks out +11mm more than stock) and R 11.0 x 18 ET 65 (this wheel stickes out +13mm more than stock)
These wheels are GT3 size (actually the rear GT3 size is ET 63, but close enough).
I'd be willing to bet that 9" wheels in front would rub (I can almost guarantee it will rub the liner on turns if you use 245 fronts on a 9" wheel). 10" wheels will rub for sure (both at the liner and the fender).
It looks like Jim B runs his 996 with 9" wheels on the front. He probably has the best track prep'd 996 on Rennlist, FWIW.
I wonder if they rub his wheel liner on hard turns.
http://www.jimbreakey.com/
Good call...and if I remember correctly I asked him in the past and he said he raced with 245/35/18'a and 315/30/18's on those 9's and 11's...so possibly this is case closed for what's optimal as it's hard to argue unless anyone can come up with a faster setup.
Now comes the question is it worth the $$$ money for custom wheels over the stock 8's and 10's that I've been using.
Andy
They will fit with the proper offsets...Rad (NJ-GT) runs 10's on the front of his 996 GT3 (with 285 rubber at the front IIRC!), but I'd bet that it would require aftermarket coilovers with a non-tapered spring design to pull it off on a standard 996 (obviously not an issue for you). I'd have to bet they rub at full lock though.
Fender liners are cheap and take about 10 minutes to change!
When picking tires the height is nearly as important as the width. Changing the height of the rear tires is the same as changing the R&P. From that perspective shorter is better. Shorter also provides advantages in front as it allows you to lower the front without changing the suspension geometry. On the other hand, taller tires wear slightly better and don't heat up quite as badly. Tradeoffs.
On width, it sort of depends on how developed you are as a driver. When you first start driving on the track you don't tend to slide around too much. You just want to point the car and have it go there. The more traction the better in that style.
Later you will feel comfortable unhooking the car a little. Using the brakes and throttle to steer. Getting the back a little loose under braking to rotate then stopping the rotation with the gas, etc. When you first reach this stage you probably want less traction/smaller tires so you can move the car around at a speed you are comfortable with. When I first switched from my 996 to my cup car I was faster on old slicks than new ones. It took me a couple of races to push the car hard enough to drive properly with super sticky tires.
At some point you'll want to maximize traction. For that stage I think our cars work best with a 245 in front and a 315 in back. I almost always used 245/35/18-315/30/18 Hoosiers. The only exception was on a small, tight track where I wanted the lower effective R&P and wanted to be able to rotate the car at lower speeds. Think auto-x. For those tracks I used a 245-285 combo.
BTW, this all assumes you have enough suspension to handle the traction.
Just my opinion. It's very possible I'm wrong.
Jim
You have tracked your C2 cab in the past. Do you think 245/295 would work well on a regular C2?
I'm thinking about what Jim said (about the effective gearing change). The 295 will have less grip, but on the plus side it will effectively accelerate better because it is shorter and a little lighter.
I think the 295 would work just fine on a C2. Between gearing and power it would probably do better with the 295. I ran the 285 on my CAB and it was perfect! I did run though the 225 front and it understeered like a pig! I had great control but just hated the understeer. Moving to a GT3 was the best thing I could have done
+2
245 front on an 8.5 and 315 rear on an 11 is what I run
with the stock sized wheels 8 and 10, you want 235 and 285 (295 will work as well and won't rub but the gearing will be slightly worse)
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