I have my first set of NT01s. After seven track days, I figured I still had a day left, possibly two, given their legendary wear. Two of the tires still have the outside dimples and on the other two, it is just barely visible, say 1/32.



This past Saturday I went up to Lime Rock for one of their "autocross" lapping days, which is basically just a hoon around a go kart type track but they have a time section on a small (1/8 mile?) oval with chicanes. We had one practice session of about 12 laps and after 7 laps I timed a personal best of 19.23, followed by a couple of 19.35. We then sat for a while and went back out for the timed sessions. One warm up then three or four timed laps. The Viper that went immediately before me got under 19 on his last and best lap so I was psyched to bust one out, lol

The vid explains the story
https://www.youtube.com/watch?v=NCuu...ature=youtu.be

So, time to retire the tires? I managed both under steer on one turn and over steer on another. On the other hand, on a track I'd have time to build some heat. Not sure I want to test the greasiness at speed though.

 

Run them until they cord.

 

NT01s feel like they get faster up until they cord. I am told that instrumented testing says this is actually a myth -- they do actually heat cycle and reduce grip, but the reduction in tread depth compensates for that by reducing squirm and making them feel faster/more confident/etc. That said, I'm not a fast-enough driver to be able to tell, and this reduction in grip is relatively minor.

The other problem with the "run them until they cord" argument is that you risk losing track time if they cord in the morning at a track day and you didn't bring another set of tires with you.

I'd say you've probably got at least 2 days left, mine have looked like this when cord finally showed up (note: these are not Miata tires, and if I'd rotated them at the right time I'd probably have gotten another day out of them):



--Ian

 

Here I am wondering if I should order another set of tires for Watkins glen, but I still have plenty of meat left compared to these.

 

949 Racing (I don't know him well enough (or at all) to call him Emilo) has a very good vid on the treadwear indicators

 

Flatter tread = more contact area = more grip
They're basically drag tires now lol

 

^^
very informative