I did a search but there is a lot of conflicting info and extraneous stuff to wade through. I will be racing on track with stock 2003 S2000 setup (OEM everything). I am looking for COLD tire pressure that will maximize contact patch but without going so low that excessive sidewall flex will cause that squirmy feel. Since I am new to this I am not trying to change handling in any dramatic way (increase or decrease over/understeer) but just looking to keep things reasonably neutral. I was thinking of starting with 36 psi COLD front and back? Any recommendations? Thanks.

 

Cold tire pressure only counts for a couple of minutes.. you will need to check it hot between sessions and I suggest you keep it about 38 hot. 36 cold will go over 40 quickly (unless they are easy laps in the cold) so you might want to start a bit lower. You will eventually find what you like, but max traction is not at max pressure.

 

After a lot of experimenting I settled on 40psi for the front and 35psi for the back (that is cold). Any less and the car was sending mixed signals. I've acheived all my PB times with those pressures.

Still, it's more of a personal prefference so see what works for you.

ps. The above recommended pressures yelded 48psi for the front and 43psi at the back when hot.

 

I'm guessing an autocross pressure would have to be higher than what you guys are recommending here because of less heat input? I've autocrossed my S2K a couple of times, and couldn't find too much to complain about with the factory recommended 34 psi cold. The car has felt very balanced, just not really grippy for the first run. I'll try bumping them up for the next event.

 

I kept them at about 38 then 37 on day 1, day two I reduced to 36 psi and felt that

1) absolute grip went up
2) the car got a bit more squirlly

So in hindsite I prefer the more stable feeling of 37 psi even though absolute grip went down a bit.

 

Good observations. There are those that are only comfortable with very high pressures but they are giving up traction to increase the stiffness. You found your comfort zone which IMO is the right way to do it. It probably will vary a little with ambient temps and different tracks. And the pressure you can read after a cool down lap is quite a bit lower than the peaks that occur during a hard lap, so in my experience the 'right' pressure will vary.

 

For stock tires and stock suspension, I like 38F, 36R HOT, as measured in the pits immediately after a session with a cool down lap.

Forget about cold temperatures... just not a meaningful measurement for the track. But I'd guess you would need to be no higher than 34/32, probably more like 32/30 cold to achieve those hot pressures. Just take a tire gauge with you, take off all the valve caps at the beginning of your track day, and check the pressures after each lapping session.

Also, check how much your tires are rolling. Look for the tiny triangles molded into the tire where the tread meets the sidewall. You want to be rolling up to, but not over, the point of those trianges. You can usually read it from tire scuff, but it is easier if you put some chaulk or shoe polish on that part of the tire before some laps.

 

Those triangles (I believe) point to where the wear bars are in the tred pattern. Are you claiming that they are also intended to indicate maximum tire rollover, or are you just using that as a convenient reference?

- Michael

 

I tried playing around with hot pressures but the pressures varied (I think the drivers side were hotter which makes sense since there are more right hand turns). I did not feel comfortable adusting the tire pressures evely after driving since this would probably result in uneven cold tire pressure and it was just too many variables for me to think about on the spot. I agree with cdelena's statement about doing what feels comfortable untill I get some more experience under my belt with this car. In terms of rollover, the S02 must be very stiff because I had no significant rollover at any of the tire pressures I ran (and even though I am new to the track I have autoX experience so I tore up some of the low/medium speed turns).


[QUOTE]Originally posted by MSRS2K
[B]Those triangles (I believe) point to where the wear bars are in the tred pattern.