Well, I finally got to test the R7's at Lime Rock Park yesterday and below are some comments. Had great weather with the temps in the high 70's.

- I went with 35/245 and 30/315. As many people heard they are Wider!
- lower profile with front tires causes front splitter to rub against ramps when loading car on trailer.
- I had plenty of room in the front and probably could have ran with 40/245.
- The rear was very close to the fender. I can only get my finger nail for the gap.
- first few laps on non-heat cycled tires were horrible. No braking, ABS everywhere. Car felt like crap.
- I did not observe any rubbing anywhere
- By the end of the session car felt a lot better. ABS still kicking in multiple part of the track. Normally the ABS does not come on for me and with these tires it happened all over.
- A lot of vibration on the front straight which I don't have a answer for since the tires were just mounted/balanced.
OK. Now for the good stuff
- For my 3 reference points track out areas: exit uphill, bridge and exit down hill the observed speed (non-GPS) was +3 mph. That is a great pickup without doing anything
- The tires stick like crazy. The car never got upset in the turns. There was a lot more grip available which I did not use.

I will look at my Traqmate data for the actual results to confirm my visual speedo to see if the +3 mph was accurate or just because of the different tire sizes.

In summary, No rubbing issues with my setup (I don't remember the specs). ABS everywhere. Tires should lead to faster lap times. Next week I will be at Watkins Glen and that will be the real test. Also, I will try to post a few pics.

 

When will you be at the Glen? I'll be there with Cups and Saucers and with ARPCA immediately following.

 

So you had Abs issues when tires were cold as well as hot? Were u changing your driving style in anyway compared to running regular r6's? I know I won't like it if abs keeps coming on. Mike

 

ABS was on when the tires were "hot". Driving style was the same. If anything less aggressive and slower to get on the throttle. This was my opening day and I was getting reacquainting with the car.

I did not like the ABS coming on, but it did not really have an effect on the lap times. It was just a little annoying and something you adjust to after a few laps.

Chuck, I will be at the Glen April 24,25,26 with Trackmasters. Friday will be open track all day with no students They run a really good program and I highly recommend them.

 

I've read that the 996 ABS expects the front wheels to have larger circumference than the backs by some %. With a 245/35, your fronts are considerably shorter than the rears, almost 10%. Not sure if that was the issue with excessive ABS triggering, or if it was just the extra grip exceeding the logic of the ABS.

That vibration you felt could have been the tires spinning on the rims. My car even spins street tires on my OZ rims, no matter how grease-free I get them mounted (and yes, I even tried the hair spray trick and it didn't work. A sticky tire such as an R7 is even more likely to spin. You can try marking them at the valve stem to see if they are spinning.

 

So how do the R7s compare to the R6s? I'm thinking of getting a set for my CS for an event coming up in May.

 

Besides all the issues I stated performance wise they are better than the R6's, and they are supposed to last longer.

I would not be surprised because of the extra grip that is causing the ABS. It will be very interesting at Watkins Glen because with the multiple hard braking zones especially Turn 1 and the Bus Stop.

With the R6's I did not have a tire spinning issue with the tires on the rim. Maybe some of the weights fell off (common with Volk T37's) and that is causing the vibration issues or this is just another bi-product with the tires?

 

That seems counter intuitive? Higher grip should mean less lock up, hence less ABS, right?

 

Just curious, did anything else change on your car besides tires? Different brake compounds?

 

If you have the room in front you might want to go back to the 245/40's on the front.

 

In terms of sizes....do R7s make 245/40/18 & 275/40/18 or 245/35/18 & 275/35/18?

 

From TireRack, here's the available 18" sizes:

P225/40ZR18
P245/35ZR18
P245/40ZR18
P255/35ZR18
P275/35ZR18
P295/30ZR18
P315/30ZR18
P335/30ZR18
P345/35ZR18

 

OP, At WGI Bus Stop try braking a little later and trail brake to the first apex curb.

 

Just used the R7s this past weekend (never used R6s). I ran 245/40 front and 315/30 rear. Never went into ABS. I don't think I can ever use the NT-01s again. I ran the pressure at 33 hot front and 38 hot rear. I only did 1 day on them and will use them next at Cups and Saucer at the Glen in 2 weeks. I still have to work out the tire pressure.

No problems with fitment. My ride height is a little high. I am running -3.1 deg front and - 2.7 rear.

Easily 2.5 seconds faster than the NT-01s at NH.

Ordering another set this week.

 

TomGT3 - that is good news about no ABS issues. Maybe the 245/40 vs. 245/35 makes the difference? I will definitely get the 245/40 for my next set of tires. The only reason I got was the 245/35 was I thought it would give me less chance of rubbing. In reality it also causes issues loading to the trailer because the front is slightly lower. Even a 1/4 inch would help in the front.

You run a big spread from the front and rear for psi. I typically keep the front only 1-2 lbs lower than the rear, but I am guessing it is working for you.