Re: Bracket racing and street tire pressure ?!?

From: Bob Tom (tigers@bserv.com)
Date: Sun Apr 15 2001 - 10:00:06 EDT


At 11:36 PM 4/14/01 -0700, you wrote:
>If I hit the drags next week, I was thinking of tinkering with the tire
>pressure on the rears. I have normal street tires on my 93 CC 2WD 5.2.
>Of all of you that have been out to the drags, what do you do to your
>tire pressure in the rears? how low do you go? how low can I safely go
>on street tires (for a 1/4 mile)? I'm just wondering what is safe, and
>also wondering if there is extra traction to be had if you go to say 15
>PSI or so... Thanks! Kevin

Kevin

Hope you have a portable, electric air pump. It's handy to
have.

Generally with street tires, go with air pressure that will keep
your tread on the ground from outer edge to inner edge. You
can lay down a couple of black strips in a lot or in the pit area
and examine to see if you have full contact patch, or if there is
sand on the ground, drive over it and then examine your tread patch.
What you want to see is, a print that shows both edges and
no 'culping' (ie middle raise off ground) between the edges.
That's why you do not want to go low on the rear pressures.
A loose guide is that you may have to bump pressure rather
than lower it to get full tread patch because of street radial
sidewall construction.

One thing for sure. If you go 15 lbs with street radials, the
tread's edges will be on the ground but most of the tread
between them won't. I use drag radials and I mostly run
them at 18 lbs.

For the front tires, you can over-inflate so that the Dak is running
on the middle of the tread. This will reduce the front's rolling
resistance. There is no safety hazard in this for 1/4-mi. runs.
My fronts say max psi of 35 on the sidewall. I put these at
45-50 at the track. Just don't do a sudden turn at speed.

Rubber compounds on most street tires do not run effectively
with heat. Avoid the water pit and just do a couple of dry,
accelerations between the water pit and tree the to clean off
all the dirt and small pebbles that you pick up in the pit area
and staging lines. HTH.

Bob Tom Burlington, Ont., Canada
'97 CC Dakota, 5.2L, 4x2, 44RE, 3.92SG, 4,275 lb (racing weight)
231.2 rwhp /340.0 lb-ft rwtorque PB: 14.737 s 93.12 mph



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