Not ran a car in pro for a very long time so trying to shorten the Learning curve. What’s everybody running pressure wise for a Hoosier 28x10x15 slick on a 11-12 second bracket car. It’s a 3rd Gen Camaro with small block and powerglide.

quote:

Originally posted by NEMO963:
Not ran a car in pro for a very long time so trying to shorten the Learning curve. What’s everybody running pressure wise for a Hoosier 28x10x15 slick on a 11-12 second bracket car. It’s a 3rd Gen Camaro with small block and powerglide.

What's the rim width? I would start at 14 lbs. & work the up.

I run 29x10.5 bias slick 12.5 to 14 psi

8 inch wide rim

quote:

Originally posted by NEMO963:
8 inch wide rim

I would start a little lower than 15 lbs. & work your way up.

Depends on how heavy your car is, what type suspension you have, how hard it is hitting the tire and how big the tire is.

Heavier car, smaller tire or more violent rear suspension you need more air. Some other factors how big of burnout, track temps and prep.

Video the car and look closely at what rear tire is doing at the hit and go from there. You need enough air in there that at your weight it is not wadding up tire too bad or not mushy or loose feeling down track.

My 3200# car, mickeys, 16#. anything less it duckwalks at the lift. Anything more, it has the possibility of spinning on the launch.

Bias slicks, or Radials?
If bias ply, I would start around 12.5 and radials around 14 or 15.
Lot of factors to consider, but those numbers should get you in the ballpark at your weight & HP. Bump that up by a half to 1 Lb if launching off of a trans brake.
Remember, for a given tire width, a narrower rim requires less pressure, and a wider rim higher pressure, to get the same contact patch.
Do a moderate burnout, make a pass, then look at the tire and see if it looks "happy" across the entire contact surface, or if it is feathering, or looks different in the center vs toward the edges, etc.
If you have someone who can video slow-mo or burst photos from the left side at the launch that will help you figure out if it is crushing the sidewalls, excess wrap, or spinning, etc.
Here is a tip to drastically cut down the learning curve/testing: Find a nice clean stretch of white concrete, (not a worn-out road, but more like a lot or a driveway). Do a short burnout, then a short launch / hit. A little splash of water for the B/O can be helpful. Obviously, you want to be smart about how, when and where you do this, but when you look at the marks for the B/O and the launch, you will clearly see if your contact patch needs more or less air. If no concrete, a newer parking lot with smoother asphalt can be almost as good. If done right on concrete, (not overdone), it will wash away easily.

With my small block camaro, glide. And 4.10 gears, i used to run bias ply et streets 28 tall, 8 inch rim. I could run 18-22 psi and never spin. Stock multi leaf springs with caltracs bars. Car ran low 11's detuned