Front tire size and it's effects on reaction times

[hotrod 80]

Just wanted to open up a disscusion about this to get other point of veiws .

I Have been playing around with front tire size to improve reaction times . I have tried 26" , 25" & 23" so far the 23" puts the truck in a better spot for my style of driving . I also footbrake race so this needs to be considered . The truck on motor leaves forward vs up and out on the transbrake and spray . Just wondering how much effect tires have and what stratagies others have . I am leaving at the first sight of 3rd amber and lights are .006-.030 . This is also at my home track . Each track seems different to me also . Anybody else run into this ? Different beams ? Just trying to move the truck into my comfort zone and looking for opinions

[GMR-PERFORMANCE]

Funny we worked on 60 foot this weekend with a rather cheap set of lights, and a dead end road that is closed.. Local police have no issue with it.. Its not good for any type of real run.. However we have gotten into the same thing.. Your times are not anything to be upset about.. with a footbrake its touch and go anyways.. I feel the tire size plays a role however your staging will play into this as well.. A small tire deep stage effects it one way and a large tire and shallow will go the other..

You running deep or shallow??

[PGSigns]

The way that you stage, the tire size and the bulbs that are used all affect the reaction time. Also the way the truck leaves on the brake verses the brake pedal will change things. One thing that also gets forgotten is the side wall of the slick and tire pressure. The roll out at some tracks also seems to not be the same. We have run into this and for a while had a list of settings to put in the delay box based on the track we ran.
Jimmy

[hotrod 80]

Originally Posted by GMR-PERFORMANCE

Funny we worked on 60 foot this weekend with a rather cheap set of lights, and a dead end road that is closed.. Local police have no issue with it.. Its not good for any type of real run.. However we have gotten into the same thing.. Your times are not anything to be upset about.. with a footbrake its touch and go anyways.. I feel the tire size plays a role however your staging will play into this as well.. A small tire deep stage effects it one way and a large tire and shallow will go the other..

You running deep or shallow??

I was about an inch in with the taller 26" tires , but with the shorter tires in smoothly just light the second bulb / any extra and im in the red . Trying to get a setup i can repeat with .

Originally Posted by PGSigns

The way that you stage, the tire size and the bulbs that are used all affect the reaction time. Also the way the truck leaves on the brake verses the brake pedal will change things. One thing that also gets forgotten is the side wall of the slick and tire pressure. The roll out at some tracks also seems to not be the same. We have run into this and for a while had a list of settings to put in the delay box based on the track we ran.
Jimmy

Thanks Jimmy , i also have noticed the differences in between tracks . Two time trials make it hard to figure out on the first outting . Also , it seems that lights will differ between lanes . I am just now starting to adjust rear tire pressure . I also run tubes in 28 x 10.5 ( 3055S stiffs if i remember correctly ) These are take offs from a 3400# car high power car . I believe this helps my truck at my power level and weight

[GMR-PERFORMANCE]

Well the red light is how you react unless you are on a D box.. I am great at the light but when the pressure comes on I have to slow myself down or I get the wonderful red light as well.. I myself think its not so much about the items you have but how you learn to work with what you have. Having a spotter can be of some help on the run what you brung nights. To get the tire just into the beam ( front part vs rear of the tire) that should help with the red light .. at least it did with me. Mybe try a .1 or .2 delay on the brake.. or hell set it for the tree.. Myslef am not a bracket guy so when it gets into that stuff its out of my area..

[Marv D]

I've got a good friend that has S/ST raced for about 4 decades. He swears he cuts .00x lights every race and uses front tire pressure to adjust his reaction times. Myself ,,, it's a crap shoot. One day im eagle eye and killing the tree with nothing slower than a 0.015 and buttloads of 0.00x. The next race I cant cut a light with a delay box, an alarm clock and optical sensors!!!
I don't know what it is,, the deeper I get in the rounds the more apt I am to shoot myself in the foot. In the 1/4 finals I seem to like to just sit at the tree and have a sandwich,, seriously,, seen some .1+ lights in the quarters just totally out of the blue., then the semi's,, go .1 red!! with a frickin DELAY BOX!!!
And it's not the box,, I do this inthe Nova OR the truck, before and after I added the box to the truck.

old fuzzy brain, or all the drugs in the early 70's finally taking their toll or something!!

[hotrod 80]

Originally Posted by Marv D

I've got a good friend that has S/ST raced for about 4 decades. He swears he cuts .00x lights every race and uses front tire pressure to adjust his reaction times. Myself ,,, it's a crap shoot. One day im eagle eye and killing the tree with nothing slower than a 0.015 and buttloads of 0.00x. The next race I cant cut a light with a delay box, an alarm clock and optical sensors!!!
I don't know what it is,, the deeper I get in the rounds the more apt I am to shoot myself in the foot. In the 1/4 finals I seem to like to just sit at the tree and have a sandwich,, seriously,, seen some .1+ lights in the quarters just totally out of the blue., then the semi's,, go .1 red!! with a frickin DELAY BOX!!!
And it's not the box,, I do this inthe Nova OR the truck, before and after I added the box to the truck.

old fuzzy brain, or all the drugs in the early 70's finally taking their toll or something!!

Yeah , full on brain cell masicare in the late 70' early 80's for me too . on top of that im on a full size forum with a half pint .

Just trying to figure this thing out . Started out sunday with .-005 on the small tires .Went in an extra inch on mistake . Just bumped in first round and went .006 . Had good light til 8 cars them waited for the toaster to pop with a .153 . Almost got it back with a long shift while he was chopping , close to my number . Just looking for the experience that this forum brings out .

[chevytruck1970]

I too have major problems cutting good lights. I've tried the front tire pressure thing with no success. I'd love to figure out a way to make it better.
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[Marv D]

One thing we have to consider here also is were not rolling into the beams with some 2100 pound ultra tight tube chassis that has to be launched on the stop to keep it from wheelstanding up out of the beams. No were trying to do it with some big ol 5 decade old, sloppy factory chssis that was hauling hay (literally) for the first 3 or 4 of those decades. A LOT of consistancy can be absorbed by a flexing chassis. I would 'like' to blame the chassis, or the brake having issues,,, but in reality I know it's 100% driver when it starts varying .1+ either side of perfect.

[hotrod 80]

The heat plays a role also . My times get worse in the heat . If im miserable , so are my times .

[GMR-PERFORMANCE]

Again Marv brings up a point that gets over looked.. Most of us are trying to get a school bus moving weight wise .. Along with a little movement here and there its gets to slow you down.

The nova I am tuning on has front and rear line lock when trans brake gets online. Without it it tends to move hence he is either taking a nap or redlights..

Marv BTW the D box was set for .4 WOW he had no idea.. I got it sorted out.. quick test run it was pulling the front tires off the bottle... went to test the NOS set up ( no bottle pressure )and it puked fuel all over the place, glad I found that..

[hotrod 80]

I can now adjust reation time with front tire pressure , but man is it on the edge . 50#= -.015-.009 45#= .008-.015 39#= .080-.090 . Still trying to figure things out . This is with 23" tire .

[hotrod 80]

Going to try going back to the 25" and running it over inflated .