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Track Tire Pressures, Hot and Cold


Guest Anonymous

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Guest Anonymous

I've heard of adjusting tire pressures back to the cold setting after they heat up. I ususally run 34F 32R on my 280Z with Kuhmos, but after a fast (for me) run, upper 30's and, on a really hot day, lower 40's are not uncommon. Should I bleed 'em back to cold pressure? Take pressure right after pit-in? What about sun heat/pressure? Thanks.

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John, why not use those bleeders that you put on the valve stems that keep the tires from getting too high a pressure due to the heat? Of course, once you're done on the track and the tires cool, the pressure will be lower than you would want to drive home one.

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Guest Anonymous

Pete wrote:

why not use those bleeders that you put on the valve stems that keep the tires from getting too high a pressure due to the heat?

 

Never heard of 'em. Also, it seems that they must have a pre-set "blow-off" pressure, which might not be as accurate (or as anal) as I am with a pressure gauge. Maybe I should invest in a nitrogen bottle?

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For track events you want to hit and maintain a hot tire pressure. For autocross you start with a cold tire pressure and (hopefully) see a 4 psi increase (for Kumhos) to about the same hot track psi.

 

What you REALLY want to accomplish with tire pressures is to control rollover and tire temps. Kumho V700s need to roll over to the tops of the tiangle shaped wear indicators. Adjust your tire pressures to get to that point. You can use shoe polish to check the rollover during each track session.

 

If you have a tire pyrometer, you already know enough (assuming you knew why you just spent $150...) to get the pressures where you want them.

 

FYI... on my 2200 lb 240Z I start with cold pressures of 26 to 28 psi and run hot pressures of 32 to 34 psi.

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Guest scca

tire bleeders are adjustable. i believe the rebco ones are around $60 a set of 4? i cant remember havent sold a set in a while. but you can adjust them to any psi you want.

 

you always want hot temp, so as soon as you come off the track. 40 seems way too high..

 

psi depends on tires but 34 -seems about the correct desire. yokohama wants more psi than R1 or Hoosiers though..

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