Pretty much yes. When autocrossing on street tires the tires get better as the tread wears off (less squirm) and are at their peak when practically bald and are done when you see cord. Throw in a couple of drops of rain though and you are going for a spin!

I used to do that back in Australia as they didn't have inspections in my state, it also didn't typically rain that much. I drove until I saw cords and then went down to the tire shop that sold used tires and put a "new" set on for $100. The one time it did rain and I gave it a little gas pulling out of a corner I did a 180 in the middle of traffic, had to quickly shove it in reverse and pull into a driveway :)

ran a set of hoosiers on the street for a while (too lazy to take them off)... man that got scary when they went all hard from too many heat cycles...

Hahaha when I was 19 and piss broke I drove on the steel belts in my 300ZX. Luckily, the tire blew when I was accelerating from a traffic light and not when I was at speed. I also remember driving on the highway during the rain and my car would hydroplane while changing lanes as my tires were running over the painted on dotted lines... That's how bad it was. Now, that I am older and more responsible and know I'm not invincible, I will never ever ever drive on tires that are worn to the point of rupturing or lacking traction.

I have 16k on mine and just received today my Hankooks from TireRack. I probably wait a few more weeks before I put them on, since I do not drive the Z in the rain and I feel the stock tires still have some life left in them.

23K miles, still have plenty of tread.

if you look in the cut out part of the tread. The lines that run around the entire tire. There will be a raised spot running sideways (touching blocks of raised tread). This is the wear indicator. If your tread is flush with that it is time for the tires to go. I tend to change mine out before it gets dead even. http://www.conti-online.com/generato...dicator_en.jpg