V225

How do you guys think 235's up front and 275's rear would work for track use on a 996 C4S? They don't make the nt-01 in 295 unfortunately, but I always felt I had too much rear traction. I really like the nt-01. It's inexpensive and non-directional. Do you think these sizes would yield a good track setup?

Thanks,
Varun

007DT

C4S... You can easily get 315 30 18 245 40 18. That is what I put on my 6GT3 that is significantly lowered and a narrow body.

275 is too skinny for the rear IMO.

mglobe

I think for track use I would increase the front tire width. Go 245/275. I've raced with that setup and it works pretty well.

V225

Thanks! would 245's fit alright on an 8.5 inch wheel?

85Gold

245's and 8.5" wheel = No Problem.

Peter

rlm328

Er? Too much traction?????????????

Land Jet

Toyo 888's are available in 295's. I don't think 275's are right for your car.

007DT

Nittos are better IMO..

And 315 will easily fit as mentioned above. More surface area more traction.

atr911

Your big problem is the differential in the AWD car. Do not deviate from the OEM sizes unless you maintain the correct ratio of front and rear wheel diameter. The diff in your car is very sensitive.

Finding the right diameters in anything other than OEM sizes is a real pain in the **** so I'd stick with your stock sizes.

Look very closely at the overall tire diameter when choosing tires. I think that a 996 should have equal front and rear and shouldn't vary by more than 0.4" (at most).

atr911

I'm going to add that another thing that many people miss when shopping for tires for a Porsche is that it requires a heavier load rating. This is one reason to stick with N rated tires as they're typically rated at 'Extra Load' to compensate for the rear weight bias (but not always actually rated for more load).

V225

Too much traction in the rear & not enough in the front = understeer. Getting the rear end to rotate in a C4S at a track is a feat.

As for the differential, I'm not knowledgeable enough to know what would cause failure. However the car came with 285's. 275 is 10mm less. Considering how people run 295's up to 315's in the rear, 10mm less in the back seems trivial. 225 or 235 is recommended for the front. 225 to 245 is a 20mm jump, so this might be a cause for concern. I might play it safe and do 275 rear 235 up front. Given the stock sizes, I can't really see how such a slight difference would be such a big deal. Please correct me if I'm wrong though, I don't know much about this kind of thing.

The R888's appear to be directional. One of the local tracks here destroys the front left tire, with very little wear on the front right(all right hand corners), so I absolutely have to be able to swap left and right tires easily.

Thanks for the replies everyone!

V225

What about R compounds and Racing slicks? I don't think they're Porsche N-rated(but I don't know for sure, do companies actually get these tires N-rated?).

Apex Rex

I'd look into the 245/275 sizes for the NT01s as has been mentioned above. If you want, you can read the specs for how wide the 275 from Nitto actually is.

atr911

Don't take it the wrong way, but I am knowledgable enough to know what would cause failure and sell tires for a living. It'll be really easy to find a good matching pair if you look for tire diameters with no more than 0.04" difference as recommended in my post.

Put simply, if the front and rear wheels are turning with the incorrect differential diameter, you're constantly working the diff and the vehicle electronics aren't able to accurately calculate slip and adjust traction control, ABS and PSM.

The sidewalls and therefore weight rating on R comp and Slicks are pretty stiff as the nature of the tire relies on this for responsiveness so load rating isn't usually a problem. Whereas a Sumitomo only has a load rating of 97Y which isn't acceptable from a speed or a load rating for a 911. Doesn't mean that your car will implode, just that your going to make serious sacrifices in performance due primarily to inadequate sidewall stiffness/strength.

Even michelin has special N1 slicks designed for the particulars of the 911 chassis though.

atr911

Nitto NT-01:

275/35 has a load rating of 95 and a rolling diameter of 25.55"
275/40 has a load rating of 99 and a rolling diameter of 26.65"

245/40 has a load rating of 93 and a rolling diameter of 25.55"

Again, just using this as an example, the 275/35 and the 245/40 are a great match for diameter BUT a similar michelin tire with an N rating has a load rating of 99 as opposed to 95 (big difference).

On a complete side note, I would humble recommend you work on technique if you're looking to rotate the car better as stepping down on tire size to reduce traction is kind of counter productive. We haven't even begun to talk about how a rear engine car such as your 911 uses much more of it's rear traction surface under braking than front or mid engine cars do and traction under acceleration is the foundation of the 911's design. Those big honkin' tires help maintain it's stability in these situations.