I just called Michelin customer service and asked if they make tire pressure reco's and they said that no, they go with the car manufacturer recommendation. He verified that I'm 36/44 taken when the tire is cold.
It is still very warm here and my tires went up 10 lbs on the outside and 9 lbs on in the inside which would exceed the 51 lb max inflation (on the rears). With this data he suggested maybe starting at 30/40 so they would peak higher than the reco but not exceed the max inflation figure.
'99 C2 Cab with PS Cups on 18" OEM Wheels.
What do you guys think?

 

over 50 is not good.... I usually drop it down 2-4lbs from spec depending on how hot it is outside.... before/after reading should be taken for each session.... street tires are tough to maintain temp. Do a search, plenty of discussion about tire pressure.

 

You shou;d be running 36 lbs hot in front and 38 hot in the rear. Starting pressures would be about 6 lbs less than the hot target.

 

+1

Listen to Bob. He knows what he's talking about. I don't care what Michelin says. I don't care what's written on the door jamb. Bob is dead on with his tire pressure recs.

Cheers,

 

Watch out for wet weather inflations. If the pressure is low enough it will let the center of the tire rise and give more hydroplaning. Wet weather doesn't let the tires warm to your normal operating temps so figure what ever additional pressure to ride with for wet. Unless of course your car doesn't see wet

 

You start low as bob suggests you go out for your first run, and then you come back and immediately check the pressures, at this point drop them down to stock pressures. You do this each run as the day gets hotter you will have to adjust at the end of each session.

The warm up lap (double yellow ) at the DE is for you to warm your tires up, take the second lap kind of easy and feel the tires but still work them hard, and the third lap onwards will be golden

 

Sounds great and will do. Am guessing I jumped 10 lbs because I'm harder on the tires (only have 1/2 doz events under my belt) and it's really hot in TX (v. Montreal Canada). Bob, thanks for sticking with me on the lbs. instead of giving me instuctions in grams. :-)

 

PSI jump will definitely vary. Usually PS2 goes up 7lbs for me but I have had them go up 14lbs when it was very cold in the morning (close to freezing) when I set cold pressures, and then warmed up in the afternoon when the sun came out.

Keep checking them after each session. For me, if the rear ever got a bit wiggly under hard braking at the end of the main straight, that was my first indication the rear tire pressures got in the low 40's. 41+psi would do that. Bleed the tires back down to 36f/38r and the car would be stable again.

Have fun!

Cheers,

 

The stock pressures are usually too high for track. Anything at or over 40 lbs and the rear end will feel unstable. Use stock pressures to go home but not on the track. As to temp and pressure increase, not knowing how hard you drive, I stuck with the basic suggestion of 6 lbs. Setting pressures ten lbs low will make the car feel mushy. Best is 6 lbs and bleed down to 36F 38R (for street tires) as soon as you come off the track. Unless air and track temps increase a lot, you will be fine after bleending down. If the day gets hotter expect to bleed off a few lbs to compensate. As to the frozen North, we had plenty of track days in the high 90's here this summer. Perhaps not as hot as Texas, but hot enough!

 

rwiii, what do you mean by noting different pressures on the outside and inside. Are you refering to a track that has more rights than lefts or vice versa which correlates to different pressures on one side versus the other?

 

+1 on what Bob said; exactly what I do and it's worked well. Check the pressure after every session and adjust.

 

When I ran street tires on track... MPSR's ran 32-34 f : 34-36 r... HOT

Depending on the track temps, ambient temps, how hard you push the car/tires..
the cold temps could be as low as 23-25 F : 26-28 R. ( I usually see anywhere from 5-10 lb growth~ this is all based on temp probe readings)

In the cold & Wet.... 36-37 F / 38-39 R HOT... (34-35 F / 36-37 R cold)

 

ttreat,
I was a pound higher on the outside or right (passenger side) on a counter clock-wise track. By defination wouldn't it have more right-to-left turns? I also have more wear after the weekend on the passenger side so will be swapping sides for this coming weekend as we will be running in the same direction. I wasn't surprised with the one pound difference given these facts.
Should I be? It could be within the margin of error in the guage. I am checking the pressure after the run--that's how I new I was gaining 10/9 lbs.
Keep chiming in guys...I'm learning a lot!

 

About right. I start by dropping 5-6 and maybe a little more after the second run. You can just check the wear line on the tire to make sure you are not removing too much.

FM

 

38 hot all around usually. If at a DE, then start at 28 cold and go from there depending on the course.

Be careful the first couple of laps.