I ran my first auto-x on r-comps this past weekend and was not that impressed but a few answers might help.

First the conditions :The tires are 2006 Hankook Z211's C50 compound, shaved to about 3/32nds, they were sticker new but had sat for a year or so. 235/40/17's on a sti with 500/400 springs, 27/24mm sways, -2.1 and -1.5 camber. The temp was about 45-60 degrees during the day and the runs were 135 seconds long.

I started with the tires at about 35psi and the first run was horrible, all over the place and spun pretty early in the run, it felt like driving on ice. I kept dropping the pressure after each run down to about 33psi but still couldn't get them more than slightly warm too touch after 4 runs.

In the afternoon I got 5 runs and managed to get the tires up to about 120 degrees? warm to touch but not hot.

Questions :
In the afternoon the tires would feel like they were at the edge of grip but then if you pushed more they would actually keep holding on but would 'slip' a little. Is this normal and should you drive them in this range of 'just slipping'?

Specifically on one sweeping corner they would feel like the front end was starting to pushing a little but openning the steering a little did not help. Strange thing was cranking on more steering actually turned the car more when I expected this to make the front end let go?

For auto-x is it more important to run with a pressure you want, ie no rollover or try to run low enough to get heat into the tires?

Is what I experience just abnormal as I was trying to use the tires in temperatures they just can't work in?

I'm glad I tried these first time at a open auto-x instead of the track.

The Z211s aren't much of an auto-x tire from what I understand. I picked up a set and ran them at an open track event last weekend and they worked just fine for me.

I'm surprised you had trouble getting them up to temp. When I put mine on the car I heat cycled them myself in the back parking lot of the local Walmart. It only took a couple minutes of pretty slow figure-8s to get them up to 140+. I would think in a more aggressive, faster auto-x setting they would come up to temp easily. It could be the 45-60° temps are responsible for the low tire temps - not much heat in the pavement, perhaps, so tough to get heat in the tires?

I ran my first auto-x on r-comps this past weekend and was not that impressed but a few answers might help.

First the conditions :The tires are 2006 Hankook Z211's C50 compound, shaved to about 3/32nds, they were sticker new but had sat for a year or so. 235/40/17's on a sti with 500/400 springs, 27/24mm sways, -2.1 and -1.5 camber. The temp was about 45-60 degrees during the day and the runs were 135 seconds long.

I started with the tires at about 35psi and the first run was horrible, all over the place and spun pretty early in the run, it felt like driving on ice. I kept dropping the pressure after each run down to about 33psi but still couldn't get them more than slightly warm too touch after 4 runs.

In the afternoon I got 5 runs and managed to get the tires up to about 120 degrees? warm to touch but not hot.

Questions :
In the afternoon the tires would feel like they were at the edge of grip but then if you pushed more they would actually keep holding on but would 'slip' a little. Is this normal and should you drive them in this range of 'just slipping'?

Specifically on one sweeping corner they would feel like the front end was starting to pushing a little but openning the steering a little did not help. Strange thing was cranking on more steering actually turned the car more when I expected this to make the front end let go?

For auto-x is it more important to run with a pressure you want, ie no rollover or try to run low enough to get heat into the tires?

Is what I experience just abnormal as I was trying to use the tires in temperatures they just can't work in?

I'm glad I tried these first time at a open auto-x instead of the track.


how did you temp the tires?

how did you temp the tires?

The truly accurate way, with my hand. :rolleyes: I'll get a temp sensor one day soon but it wasn't on the top of the list yet.

I know it's not accurate but I also know they were only mildly warm to touch, no where near as hot as my street tires after a track session or even after a couple of auto-x runs on a hot day. They did get just hot enough to start picking up stones that were sunk into the tread.

The pavement was really cold, measured by the fact that my feet were freezing in thin shoes.

C50 is a roadrace compound. It does not like being cold. On a warm day, it usually takes me about 2 laps on a roadcourse to get my C51 compound tires up to temperature and make them really stick. For an autocross it would be difficult to get them up to temperature on a warm day, let alone a cold day. I think you'd have better luck with the C70/C71 tires.

This is what I was wondering. If it was just too cold and I never got to the correct temperature then all the questions about feel/slip of the tires are not valid.

I have the same tire and compound, but in 275...in 50 degree temps on Saturday, they did not heat up enough to really start gripping at all, even with a codriver in my car.

At the subie challenge a few weeks ago it was 80 or so degrees and the run groups were small, so there was only about 5 minutes or less in between runs for my codriver and I, and the tires loved it.

[QUOTE=aus_taz;19695888]
First the conditions :The tires are 2006 Hankook Z211's C50 compound, shaved to about 3/32nds, they were sticker new but had sat for a year or so. QUOTE]

Not sure what you were expecting, but hard compound, old tires and cold day are a very, very bad test case.

New Kumho 710s let me run 2-3 seconds faster than my old Hoosier A6s on a warm day. The kumhos did not appear to be the right tire for first heat of the day at Nationals though, when the outside temperature was 52 degrees.

C50 is a roadrace compound. It does not like being cold. On a warm day, it usually takes me about 2 laps on a roadcourse to get my C51 compound tires up to temperature and make them really stick. For an autocross it would be difficult to get them up to temperature on a warm day, let alone a cold day. I think you'd have better luck with the C70/C71 tires.

Yes, but he is referring to the Z211 which only came in C30 and C50. The C70 compound option wasn't introduced until they released the Z214 tires.

FWIW, I've been running C50 Z211s on my D-Stock 06 WRX TR this season and they grip quite well. They remind me a lot of the Victoracers (my past DOT tire experience has mostly been with the various Kumho DOTs).

I'm most likely going with a C70 Z214 next season which, from what I've read and heard, is more along the lines of a V710 / A6 instead.

I had no idea what to expect from these, I know old tires, cold day etc is not the best. I got them as an experiment into r-comps, for a really cheap price, which I think they will do well at.

I think we've established that it was too cold for the tires and I never got them into the correct temp so what I'd like to find out is if this vague feeling will go away once they get warm and if I should drive them a little more into what people call the slip angle vs street tires?

Next test is 2 days at NHIS in 2 weeks which they should do better at.