How would handling of a C2S be affected by slightly wider front tires (i.e. 245)? Would they even fit? And is there any noticeable handling difference with 305's on the rear rather than 295's?

 

Most likely you and I aren't talented enough to feel such a minor difference. But, there IS a reason that Porsche settles on the sizes that they do.

 

Mostly tire availability....You would most likely need more neg. camber to fit the larger tire in. Since Porsches with factory setting push, there would definitely be a benefit to turn-in. For a street car I don't know if you would feel the difference...

FWIW, I bet a stock 997S with 235/295's would post faster lap times than the same setup with 305's. Again, it's matter of push....

 

Theoretically, more contact patch up front would mean more grip and less understeer. 245s want wider wheels of 8.5", though you could probably stretch it (listed wheel width is 8-9" with 8.5" being optimal).

From my research, 245s up front are about the limit (265s want 9.5" wheels and I was told might have clearance / rub issues). 295s to 305s are fine at the rear on an 11" wheel, and 315s might be pushing it (added weight for not much gain, might rub, etc.). Of course all of this is in regards to 18" R-comps, but I think you can apply it to street tires as well.

So, the experts advising me on track set ups believe a 245/305 RA1 setup or 235/295 PSC would be pretty much optimal.

245/295 (if tires in those sizes are available) might give a "closer to square" setup that should reduce understeer slightly. It's my guess that Porsche, like BMW, plans in understeer as it is easier to save than oversteer. So why sell a car with 235/295 instead of 245/295 - perhaps to dial in understeer for a margin of safety.

 

I'm thinking of a 9" wide wheel with a 255 front and 305 rear. Is a 9" wide wheel in front even feasible on a 997?

Dave

 

8.5" rim at front reduces inherant understeer a bit. this is with the stock 235 tires.

 

Spoken like a true domestic car guy! No, seriously, I'm of the same school of thought: stuff as much rubber under the car as possible. I know that NJ-GT runs 265 and 335 on 9" and 12" on his 996 GT3. Should be possible on a 997.

CCW would be the guys to fab something up; I'm really looking forward to seeing the C14 on a 997. I just ordered a set of C14s for my M3, 9.5" and 10".

 

9" fit just fine - had one wheel guy just put a set of 9" front and 11" rear on a 997 narrow body to demonstrate. His only suggestion was 265 rubber might be a problem under extreme cornering and depending on suspension settings.

There are plenty of options... 235, 245, 255, 265 up front and 295, 305, 315 rear. I think I'm going to try what John at ccwheel suggested first - 245/305 Toyo RA1 on 8.5" and 11" C14s.

 

Birds of a feather flock together...LOL...I am running 255 fronts on a 9" wide wheel on my M3 now and it dialed almost all of my push out of the car. I think the 255/305 setup would be perfect. I just wish the OEM wheel was 8.5" wide to begin with...CCW here I come..

Dave

 

Thanks for the info Ron..BTW..did you say it took 47 days after your car was built to get it into your hands?? You are on the east coast and my car is being delivered on the east coast...trying to line things up.

Dave

 

nkhalidi,
Where did you get those numbers ?
Those are awesome !
Vinyl or magnetic ?

 

That gray 996 isn't mine, just a photo from the CCW website. I don't know whose car it is.

My numbers are far inferior, notice the duct tape 1:

 

Dave, Ron: Looks like some nice CCW track wheels are up for sale:

https://rennlist.com/forums/for-sale-ads-member-to-member-fs-wtb-free/324930-fs-996-gt3-tt-c2-c4-race-parts-slicks-and-dot-race-tires.html

 

Thanks for the tip! Those are MONSTER wheels 10x18 and 12x18 - I'd have to roll my fenders. Lots of goodies on his "for sale" list for sure. Now if I could find 8.5x18 and 11x18 to fit the rubber I'm after...

 

I think you will find much greater differences in handling qualities by changing tire type, as opposed to a one-size change. I'm interested in getting some 18" wheels for track use, but I'm not sure if I will increase the width. In feeling around the front strut of my car (997S), I have probably 3/4" of clearance with the strut at the sidewall, which is plenty. But, at the top inside corner, there is much less clearance with the bottom of the spring perch. I can just squeeze the tip of my little finger in there. So, given the same profile, a wider tire is also going to be taller, and I don't think you can go far in that direction. I have maxed out the front camber, which isn't much, and I would never change that to get more tire clearance. Given the experience of others, I think the answer is yes, you can probably go a bit wider, but I'm not sure you will feel any effect. Stickier tires are probably a better solution if you want more absolute grip. If you want to change the balance towards less understeer, you may have to invest in some suspension work to get more front camber. IMO, not worth it.