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Old 01-08-2019, 11:26 PM   #2
Tom Goldman
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Join Date: Jan 2003
Location: Allentown,PA
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Default Re: Air Pressure Front & Rear

Well Cal ,this stuff is pretty much scienced out and pretty out in the open .
Bumping front pressure up or down can change RT'S a few thousandth's on fast cars , but the slower the car and bigger the tire ,usually the bigger the change is. ….But a hundredth in RT is usually about it, at least in my experience with .90 cars with small tires.
Bumping front pressure up will slightly lower the RT ,BUT ,60' should increase by nearly an equal amount.
I would never recommend going above 45# on our cars with small front tires ,the foot print just gets too small and the car gets "darty" down track.
Stockers blow them way up ,sometimes 50-55 # for heads up or record runs because it lowers the rolling resistance .
Rear tire pressure ,everybody's favorite subject , not so cut and dried . some run ridiculously low pressures and plant the rim into the ground so hard the sidewalls are shot in 20-30 runs.
Rule of thumb I've always followed is the smaller the tire is the more pressure it requires ,Larger tires ,less pressure. ….more weight ,more pressure.
You can have a car that murders the tree at 6# pressure but is inconsistent in 60' . ….Take the pressure to 7 1/2 -8# and the 60' is deadly but RT's fell off a bit.
I've run my 16x33 Hoosiers as high as 8 1/2# at 2250# in the car and they didn't spin.
Then you can adjust the shocks and start all over again !!!
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