Ran these on the roadcourse at Gingerman Raceway in South Haven.
Tire size was 265/35/18 all-round mounted on 18x9.5 Volk TE37's. Car is running the KSport suspension with Stoptech's 355mm front BBK, stock Mitsu rear calipers with KVR rotors and Carbotech's Panther Plus pads in front and Bobcats in the rear, Stoptech stainless lines all-round and ATE SuperBlue fluid.
First off, after deciding to go with separate winter and summer tires (I'm in MI so we do get our fair share of cold weather and snow, especially lake effect in southwest MI), I decided to look for the best of each. I've already done a review of the Nokian Hakkapeliitta RSi tires I got for the winter.
In looking for the best summer street tires I considered R-compounds but decided to go with a true street tire since the VR4 is now my daily driver and R-compounds have a heat cycle life. After 'X' amount of heat cycles, even if there is sufficient tread remaining, R-compounds tend to harden and you lose the extreme grip that they provided when new. They might be good for a weekend track/fun car or someone who drives like a nut 90% of the time (so they'ld wear the tires out before the heat cycle life is up) AND has the funds to replace them every 5000 miles of hard driving, but I wanted a true street tire that could also be taken to the track so my choice was the AD07.
The AD07's handled admirably at the track. Incredible grip for a street tire under braking and hard cornering and they held up to the heat well (a problem which turned me away from the Falken RT-615's). Even though the track was fairly hot and I pushed the car progressively harder and harder, the tires did not start to feel 'greasy' or lose traction.
After the first session, I inspected the tires to see how they were holding up and was at first concerned at the melted rubber on the edges of the tires. Upon closer inspection, I discovered that the melted rubber was what had been left behind by other folks' tires that mine had picked up.
I will also concur that these tires, when pushed past their grip limits, retain amazing traction at high slip angles. I guess there's a good reason (other than simply from sponsorship) why this tire seems to be used by well over 60% of the drivers in D1 Drift events. Nobuteru Taniguchi when interviewed by Yokohama at the AD07 testing mentioned that his first grip laps proved that the tire had great traction but he was amazed at how much traction they had when drifting at high slip angles. Some tires have very high static grip but when they start to slide, they have poor dynamic grip and once they break free, they're difficult to control. The AD07's could be progressively pushed harder and harder, and when I found the static grip limits and exceeded them, the car was still very controllable and breakaway was progressive and easily corrected.
I did try to drift through one of the turns on the back half of the course and promptly received a stern frown from one of the track marshalls/flaggers coupled with a warning waggle of their yellow flag, so I avoided any further playing in that regard.
The tires also wear quite well and aren't too easily prone to flatspotting. On my very first lap out, I forgot part of the course (been a few years since I drove at Gingerman) and came into turn 3 a little too hot. There's a rise just before the turn and I thought there was enough room to brake after the rise and realized my mistake when I topped the rise. Hit the brakes but the car was light and I locked up the brakes and came screeching into the turn. Avoided an off-track excursion by less than a foot. I thought I might have flatspotted a tire there (since they are a relatively soft compound), but the tires are fine.
After I regained familiarity with the track I started pushing harder and harder It was fun running down the folks ahead of me on track, but I ran in the beginner/intermediate sessions so there were a fair number of novices (3 of whom slid off track right in front of me). Yes John, next time I'll sign up in the Advanced/Experienced group
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The deceleration provided by the grip of these tires and the 355m Stoptechs is amazing for a street-tired car with (somewhat) streetable pads (the Panther Plus squeal like a stuck pig when cold).
Attempting to even approach the cornering grip limits of these tires on public streets would definitely subject the driver to a ticket if observed by any LEO nearby.
I'll update when I have some wear info after running these several thousand miles. as yet, I haven't driven them in the rain, so no comments on that yet, although they have reviewed/tested quite well in the wet on TireRack and in car mags.
For now though, if asked if I would buy these tires again, I would have to say YES, absolutely. If you're in the market for a set of summer tires and your criteria preclude R-compounds but you still want fantastic grip, give these a look.
Max
PS. I need to get one of those GTech Pro RR's because I'm really curious to know what kind of lateral G's and braking G's these tires are producing.