Is there a 'rule of thumb' on reaction time versus rollout? i know people who lower air pressure for more but i need to get a quicker R/T for my slow car and deep staging is not an option. Thanks for any help. Car in question is a 1996 Camaro going 8.0s in eighth mile.

What size are your current front tires? How much air are you running? It's going to take some effort to get an 8.0 car to react fast enough. I raced one for over 10 years. 23" fronts are a must.

25.6 is what an online calculator says my 245/50/16's are. I would like to stay with the factory 16x8 Camaro wheels. This may be a chore getting that short of a tire on that rim. I had tires unknowingly on 30 psi when i raced last. 3 wks ago. I raised pressure, at home in shop, to 38 psi and done some redneck measurements and this helped rollout some. Rear gear is 4.10 with a factory 3.08 first gear.

Don't know what you are running for front tires, but look at the block of fine print on sidewall that shows max load rating, etc. It will show the maximum recommended pressure. Also will show the Speed Rating, and higher ratings are by design going to be of higher quality construction, and generally able to tolerate higher air pressures. Go with that PSI and see if it helps. (Note - I am not recommending you exceed the manufacturer's pressure rating, but I have gone as high as 54 PSI on my front runners to get a decent R/T when foot-braking a slower, heavy car. Tires were new and in perfect condition, would never do that on older or weather-checked tires).

I'm running stock type radial street tires on the front with stock 16x8 rims. Side wall shows 35 but i believe i could get away with 40psi.

Hard to deal with street tires but along with the front try more in the rear. Might help. If you race the same place all the time and can't deep stage try seeing how many bumps it takes to put out the top bulb and then take one less bump---lot of roll out you can eliminate which results in better lights.

If you race the same place all the time and can't deep stage try seeing how many bumps it takes to put out the top bulb and then take one less bump---lot of roll out you can eliminate which results in better lights.[/QUOTE] This is what i believe i may have to try. I do want to exhaust all options first. Shorter tires probably. One track planly says no deep staging and they will not wait, the other allows it but will not wait either. Another third track US43 does the no box thing so everyone is ultra competive and i like regular F/B.

When you stage, drive all the way through the beams till the top bulb goes out, then back up till it comes back on again. This may help tighten your RT.

quote:

Originally posted by Tom RedRX7:
When you stage, drive all the way through the beams till the top bulb goes out, then back up till it comes back on again. This may help tighten your RT.

A lot of tracks don't follow NHRA rules,but this is in the NHRA rulebook.

THE FINAL STAGING MOTION, USING APPLIED POWER, MUST BE
IN A FORWARD MOTION, GOING FROM PRE-STAGE TO STAGE
POSITION

I race a lot of different tracks and don't know of 1 that will allow that. The last move staging must be in a forward motion is the rule. Not saying some hill billy track won't allow it.

quote:

Originally posted by ferndaleflyer:
Not saying some hill billy track won't allow it.

I was trying to be "politically correct".

Have raced at tracks that allowed backing into the stage. Real easy to mess with the guy who's backing in, and I think that's why most don't do it. Similar to quick staging against a turbocharged car which has happened to me quite a few times.

quote:

R

try 45-50 lbs

doesnt more air pressure make a tire have more rollout ?

No

I wish there was a rule of thumb on R/T vs rollout. I measured it rollout kinda with 32psi and then 38 psi and it helped about a half inch. I found some 225/50/16 that according to manufacture specs are 25in tall and same tire in 245/50/16 is 26 inch tall.

quote:

Originally posted by Mark Cmar:
doesnt more air pressure make a tire have more rollout ?

Most tires, it shortens the rollout because the contact patch get smaller. The leading and trailing edges of the tire raise up and makes for a shorter rollout.

I have heard in that with a really short bias ply front, more air can make the tire larger giving more rollout. I buddy of mine swears this is the case on his 23" front runners. To me, it doesn't make sense unless he is running air pressures to low to start with. Any air added should make the contact patch smaller and make the rollout shorter.

I feel like i can see this same thing happening on my dragster.

quote:

Originally posted by JPosey:
I feel like i can see this same thing happening on my dragster.

They look like they grow alot from 25psi to 35psi.

quote:

Originally posted by Mark Cmar:
doesnt more air pressure make a tire have more rollout ?

Technically, if you measured the circumference with a tape, yes it would increase that dimension. But in terms of dragstrip rollout, (the distance of forward travel needed to clear the beams), it is less, as Ferndale and Tom stated. Same terminology, but different measures.