Originally Posted by captain_pants

An interesting observation for me this weekend. Saturday was my first autocross on 255 Z2s on my AP1 STR car. I broke the tires in by driving about 60 miles on the highway and doing about a mile of 'slalom' on a deserted road.

The tires were quite peaky, with a very noticeable drop-off after you cross a certain slip angle. They really demanded precision more than any other tires I'd ever driven on. My driving style is a little sloppy, often exceeding the peak grip with some sliding. That hurt a lot with these tires! If/when you cross the line the car just slides and slides, being a little tough to bring back in line. This lines up with many of the tests I've read online.

Then my diff blew up on my 3rd run. So I hopped in a friend's STU STI for Sunday's event. He's got Z2s with probably 30 runs on them. They were a very different tire! Still quite 'crisp' feeling, but not so punishing if you exceed the slip angle that generates peak grip. I know, I know, STI vs. S2000, but I own one of each and autocross them fairly regularly so I can somewhat filter out the car differences. Very interesting! Now I want to do more and more runs to break these puppies in! I believe that many of the tests published so far used low-run Z2s that exhibit this peaky condition, and those reviews would change if they had 30+ run tires.

Now, anyone have an AP1 diff for sale?

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On a side note: I got in themikewoo's AP2 for my final run on Saturday after my diff blew. Thanks Mike! He's on some terrible all-season tires that the car came with. Wow, that was comically fun! It felt like the car had 500 lb-ft of torque, with the ability to boil the tires on the slightest command from my right foot. Just a mere 6 seconds slower than my previous run. LOL!

Originally Posted by captain_pants

It started making noise at the Lincoln Pro. So I swapped in my spare that I bought many years ago. But it made the same noise, so I wrongly assumed it was something else. I was trying to figure out the source but couldn't, so I figured I'd keep going until it became obvious.

I'll post the video of it's final run in a few days. Sounds normal at the start, then you get a hint of noise about 20 seconds in, then by 40 seconds it's really loud. Loud enough that I heard it over the red mist and other car noises so I shut down the run early. I had between 500 & 600 launches on the first one, many on R-comps with 9k launches on concrete. That diff didn't owe me anything! I am bummed the 'good' spare was actually bad.

Originally Posted by jeffjanzen

I ran my new 225/50-16 ZIIs this weekend too (RTR AP1). No break-in, very peaky and difficult to find the optimum slip angle (though I must admit that's partly what attracted me to these tires - it sounded like a fun challenge!). I'm looking forward to getting more runs on them and seeing how the performance changes.

I also had a chance to try them in pouring rain and standing water (very similar to 2013 Spring Nats morning conditions), and HOLY CRAP THESE TIRES KICK ASS IN THE RAIN! The limits were so much higher than I expected, and the rain breakaway wasn't nearly as peaky as I've experienced with other sticky summer tires. I'm pretty happy with my tire choice so far.

Originally Posted by odb812

Does anyone have some good long-term feedback about how these deal with heat on the track? I've seen a few posts, but nothing definitive.

Originally Posted by Sebring AP1

On track they heat up fairly quickly - slightly quicker than an RS3 or an RE11A but it's not terrible. One warm up lap, two hot laps and by then they start to get too hot. I found they work best at 35-6 hot pressure, and I normally run 37-8 on my street tires. It might have to do with the way the tire heats up.