To Air or Not To Air

[jspell]

This pic shows more wrinkles than expected...2585's on 12" rims with 7.5lbs.  It drives into the wheel stand...maybe drop the pressure and "slip" the tire more? 

[rooman]

Are the 60' numbers good? Does it go straight while carrying the wheels? Is it pulling the motor down? Is it shaking? If the answers are yes, yes, no, no I would leave it like it is. Might try lowering the bar a little rather than changing the tire pressure if you want some wheel speed and less height at the front wheels.Also think about the fact that if it does get some wheel speed and gets up on the tire sooner that may allow the front to come up even more due to the increase in ride height at the rear end.

Roo

[jspell]

Hi Roo,  it 60' at 1.08 / 1.09, when it rides the bar it may try to drive left occasionally, it does not pull the motor down, launch at 4200 converter jumps to 7000.  it shifts into high 1.75 seconds into the run, no shaking at all. thanks for your feedback.   

[masracingtd1167]

John I don't think that the tire looks bad at all in that picture ! I started playing with tire pressure with mine last year and it made a difference . We started at 5.5 and started going up .25 at a time and left off at 6.5 with the 60 ft's getting better each run ! I even went back to 6.0 from 6.5 and slowed down a little and went back to the 6.5 and picked up again ! Even though you and I run the same tire what works for me may not work for you ! The only way you can really tell is to make a run the way it is and try a pressure change from there . Double check your bar to make sure it is perfectly straight . That can make your car drive off one way !   

[jspell]

Thanks Bill...I wasn't sure if it was crushing too much in the front portion of the tire...is there a point where too much air might cause "bounce" in the shutdown area?

[buickfed]

seen them long and short, what dictates the length of wheelie bars?

[ricardo1967]

The shorter they are, the more they unload the drive tires when they're holding the car from further wheelstand.

[JrFuel Hayden]

I run 5 3/4 to 6 1/4 in my D2585's in our Heritage Jrfueler, but most of the time I run 6 lbs on my 12" wide wheels. When I'm looking for more tire speed I lower the pressure, more bite more pressure.
On the other side 6 3/4 was just too much tire spin for our combo [ 870 hp]. The up side for you, running 7 1/2 is less tire wind-up so better RT. I would worry about tire shake, but with lower HP you might be getting the tire speed you need and not pulling the RPM down and getting out of good HP range.

Feel free to call with any questions, 805-444-4489
Jon