tire pressure

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RyanUpdike70

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What kind of tire pressure should I run in my front tires I ran 15 pounds also I am running 10 in my Hoosiers and I was told to run 15 thanks
 
That's a wide open question not knowing the tires and application but 15 up front sounds low for just about anything.
 
There should be recommended pressures on the sidewall of the tire. I would say 28-32 psi to be safe. tmm
 
I do know that some guys play with front tire pressures having to do with reaction times on racing front tires. So I've been told,,Lower pressure helps slow/decrease red light starts,...I still run street radials on the front set at 40 psi
 
Darter6 said:
I do know that some guys play with front tire pressures having to do with reaction times on racing front tires. So I've been told,,Lower pressure helps slow/decrease red light starts,...I still run street radials on the front set at 40 psi
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good advice here. bad reactions times can be decrease with upwards of 40psi in the front. too good of reaction/red light can be increase with 15-20psi. the rears depend on the slick size and the hotrods weight. large slick about 7psi, small slick about 10psi. radial require a different psi and someone else will have to answer that as i don't know.
 
RyanUpdike70 said:
Running at 15 pounds going up to 30 will it effect the 60ft
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Any change in tire pressure or tire diameter will affect '60 and RT's. The amount may not always be noticable because of all the different variables, but the difference will be there.
(i.e.: YOUR reactions, precise location of the car on the line (shallow/deep), side-to-side location of the car relative to any crown in the track and/or rubber build-up, etc.)

Personally, I think 15 lbs is asking for trouble. I worry when I have to go down to 25-26lbs because a track has an extra tight rollout.

As for slicks, larger slicks tend to need less air pressure. But I've seen 9" slicks run at anywhere fron 12 lbs to around 30! Personally, I found 21 lbs to work best in my Hoosier 9" lightweight radial slicks.
 
Ryan, If you get up to 40+ lbs in your front tires and your average RT's are still slow, consider shorter front tires, higher launch RPM and/or a looser converter. Carb tuning the accellerator pump circuit can also help RT's, giving it more "snap", as well as frame connectors, torque strap to limit engine movement, aluminum or poly front spring eye bushings, more air in the rear tires IF you don't compromise traction (contact patch), but a wider rim with the same width slick can allow for more pressure to be run, and probably a few other things. Every little bit helps.
 
The pizza cutters on my car get 42psi. As others have said, you can change pressure to adjust RT....but 15 is WAY TOO LOW.... especially with a big block up front.
 
I run 45 lbs with my front runners.
7.5-8 lbs in the rear slicks.

racecar.jpg
 
Someone asked about Drag Radials,,I run M/T Drag Radials(rear) 235/60/15 at 20 psi.
Car is low horsepower, works well at that pressure.
 
run 36 up front 20 to 24 rear 9" hoosiers
 
36 up front in my DS2's and 17 in back with MT ET Drags. You said it made a difference, how about posting your results.
 

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Ran 32-46 up front depending on what track I was at and 9 in the rear.
 
drjay0 said:
36 up front in my DS2's and 17 in back with MT ET Drags. You said it made a difference, how about posting your results.
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drjay0, Do you still run 17lbs. in your slicks? I've run 13 lbs in my 29x12 Hoosiers for several seasons but it will only hook reliably on a well prepped track. I'm considering trying 15-17lbs. to see if it will be more reliable. I figure the best way to tell is testing it on a Friday night when there are lots of street cars there pulling up what little track prep might still be there.
 
15 sounds like your running it half flat. The side wall will have the recommended pressure. As for the rear, every car and tire combo is different. There is no exact pressure set in stone. You have to test, test and test. Move your pressure up or down until your tire leaves a even print from side to side. Heavy on the edges then your to low. Heavy in the middle and no edges, to much pressure. Find the middle pressure where your tire leaves a even print. When it's right you will find a nice evenly feathered edge appearance across the tire from edge to edge.
 
My small block bracket bomber, 11.30 car had M/T 28.5 X 11.5. It took 11 1/4 psi. to make a full print. Moroso front runners at recommended 55 psi max. Here's a photo of that combination.

bob 2.jpg
 
RockinRobin said:
drjay0, Do you still run 17lbs. in your slicks? I've run 13 lbs in my 29x12 Hoosiers for several seasons but it will only hook reliably on a well prepped track. I'm considering trying 15-17lbs. to see if it will be more reliable. I figure the best way to tell is testing it on a Friday night when there are lots of street cars there pulling up what little track prep might still be there.
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I went from 13 to 17 in my hoosiers it was hard to believe the difference I'm now a believer
 
Darter6 said:
I do know that some guys play with front tire pressures having to do with reaction times on racing front tires. So I've been told,,Lower pressure helps slow/decrease red light starts,...I still run street radials on the front set at 40 psi
Click to expand...
a shorter tire will leave the beam sooner. a taller (aired up) tire lwill stay in the beam longer.
 
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