I wanted to post a slightly in-depth update about this set up and a few other things so my experiences are on paper for everyone else.
The 18" wheels are working good so far, with a few slight hiccups. The clearances are very tight with my wheel specs. Two areas of concern is the inner lip to the strut, and the inside wheel surface to the brake caliper.
The clearance is so tight to the caliper, the rubber "clag" you sometimes find on te inside of your wheel after a track day actually hits, rubs and melts to the caliper. Not a catastrophy, but what if it were a rock or something? See pic below. The other clearance location is the strut. I dropped a wheel and just barely bent the inside of the wheel. This bend was enough, though, that it started rubbing the strut. Strut should be ok, but I will likely replace the wheel. A 3mm spacer solved the issue. Even though the wheels fit without a spacer, after this issue I would recommend a 3mm just to be on the safe side. See photo.
As I said a few post back, I wasn't entirely happy with using the DH slicks during track days. That opinion hasn't really changed. I opted to try a 315/335 Nitto NT01, the size was appealing and I've used these in the past. With that said, anyone who has followed some of my previous threads from my time with the SS 1LE will know that I was not fond of the NT01. I wanted to try it again before I gave a definitive opinion.
The NT01's are 315/30/18 and 335/30/18, because I know I will get asked. No issues with fitment. The tires actually appeared to "balloon" a little bit, even with an 11" and 12" wheel. Pressures for these tires appear to be all over the place, some will say run low around 34psi and others recommend higher. Back when I was racing Spec Miata we used an RA1 and R888 which shared the same compound and we were finding that 40-41psi was the ticket (completely different car, I know).
Two weeks ago I took the car out and did some testing at Thunderhill West. This is a small, tight track that favors smaller cars. It just happened to be an insanely cheap day so I used it as a chance to test the set up.
I started out with a target of 34 psi hot and it was TERRIBLE. The car had no bite, it was very sloppy and it would just not turn in. Pushed like mad. Over the sessions I increased pressures and using a tire pyrometer found
39-40PSI to show the best tire temps.
With higher pressures, the car's behavior was slightly more manageable. The turn in never felt as precise, almost as if it had a delay, compared to other tires. I then started to adjust my driving habits and found the NT01's actually responded quite well to "on-throttle" steering. Meaning, as I rolled onto the throttle the car would settle, the front end would bite and I wouldn't understeer through the corner. After this adjustment, the car became even more manageable.
At Thunderhill West I was able to run a 1:21.X on NT01's compared to a 1:20.X on the stock G3R's.
Fast forward to last week where I attended a track day at Thunderhill East (the big track). Surprisingly, I had never been on this track since my days racing Miata's years ago. It took me awhile to re-learn it in such a different car, but ended up running consistent 1:58's. Again, on NT01's and facing similar handling issues as I was on the other track.
I ended up swapping a highly used set of stock G3R's onto the car for the last session just to get another comparison.
Holy shit, what a difference. I immediately ran 2 seconds faster with a 1:56.3 with lots of time to spare in a handful of corners. Turn in was crisp, the car felt neutral and balanced again, what a nice feeling. Rock on GM and Goodyear, they sure created a superb car.
Just goes to show you, aftermarket is not always faster.
On the flip side, I only get around 7 heat cycles (session) out of the front G3R's before I cord the inside. That certainly makes for an expensive tire when you run 15+ days a year. The NT01's have 8 cycles on them thus far, and are showing good signs of wear. I expect to get double the life out of the fronts. This shows that they can be a good alternative when overall lap times aren't a concern and cost-to-play is.
Here's a video from an AIM Smartycam of that previously mentioned 1:56.3 lap, enjoy!
And some random pics from Thunderhill West
