anyone use different than the factory recommended 36/44 for nitrogen filled?

 

factory settings are for the street not track...track settings depend on your driving style, type of vehicle and it's weight, brand/compound of tires and the particular track and the track temps that particular day...if you are running Michelins either PS2s or MPSC they don't like hot pressures above 36f 40r...if you are pushing the car (8-9/10ths) you will increase cold pressure 10-15lbs during a 20-25 minute session on an 80 deg day (toward the low end in the morning/high end in the afternoon)...I usually start out at 26f 30r in the morning (since I don't push that hard first time out) and check hot pressures immediately after first run...if you are new to tracking you will not raise the pressures anywhere near that much and would probably be ok at 32f 36r

 

thanks much for the recommendation. do you really get that much increase in pressure with nitrogen? i thought it was supposed to reduce or eliminate the affect of heat/pressure.

 

I'm confused by all the hot pressure/cold pressure/numbers talk.

... Sorry, I'm a noob & haven't tracked my car yet.. But this is interesting, lol.

 

I have nitrogen and expected the variation to be lower, but it is about the same. I started at about 30F 32R and was hitting 40-44 at the end of the session. That is a bit high for the rear, so I was dropping them a bit as the day went on. The basic advice I hear is to start at -8 from your street setting and adjust as the day goes on with a hot target of 38-40.

 

Nitrogen eliminates any negative effects that unwanted moisture in the air might contribute but it doesn't stop the pressure from increasing as the tire get hotter...

 

Yep, I ran both PS2 and MPSC at 33f 36r hot. This is what works well for me.
Car is a C4S bone stock with shorter springs.
Running higher than that makes the car really squirlly when driven > 6/10 ;-)

 

Don't drink the coolaid. Just run air. It's too much trouble to run nitrogen and you never get all the air/moisture out anyway.

What tires are you running?

-td

 

i get the nitrogen for free from buddy's shop, so i figured why not.

sit down before you read this...

kumho ecsta spt max perf summer due to 25k mi/yr dd with 90% freeway commute and 2-3 track days a year. they aren't mpsc's, but will get me around the track quick enough to enjoy it (don't care about lap times). planning to replace with the new sumi 3's when needed.

i now have H+R sways (rear on softest setting). everything else suspension wise stock.

 

Shoot for 36-38 hot all the way around. Depending on the day, you will have cold pressures around 28-32.

FWIW, last weekend at the track was a raining morning. I used my street tires (Sumi IIs) in the rain. Totally crap. I got passed by a Range Rover one of the other instructors took out. It dried out after lunch, and I didn't feel like swapping tires. The Sumis weren't as bad in the dry - but still pretty crappy. About 10-12 seconds a lap slower than my normal DE tires. On the plus side, they are way cheaper

-td

 

What tires are you normally running on the track when dry? Trying to figure out what you compare the Sumis with?

 

I don't normally run wet tires. When it rains, I just use my streets.

In the dry, I normally run DOT R-comps - of various makes.

-td

 

i have heard from several the new sumi 3's are significantly better than the two's or ecsta spt's for the track (dry anyway).. anyone????

 

I'm assuming this is for an 18" tire? I have 225/45/17 and 255/50/17 .... and PS2 ... what *hot* pressures should I be running...?