Front tire size question

[Drtmod5]

What affect does changing front tire height have on your run? In other words what #'s will change? Thanks, Dave

[FullTimeRacing]

I have it in my mind that a TALLER tire will slow your reaction time.

Do to longer roll out.

[DirkaDirka]

Ok how does the front tire size effect the times? I am only asking cuz I dont know and I wanna learn as much as I can for when I build my car for the track.

[curtisreed]

Taller tire will slow reaction times and give quicker et's as said because of more roll out. Basically you get a longer run before you break the beams so you are already moving more at the start of the clocks. Or with the taller tire you can roll in deeper so that you are further down the track and slightly ahead of the other guy at the start.

All of this is small amounts though, you are not going to pick up a couple of tenths with a 2 inch taller tire. This is one of the reasons the Top Fuel guys went back the the 17 inch tires from the short airplane tires years back. Going to a shorter tire is just the reverse of all of this.

Curtis

[Tod74]

More rollout will make the car ET and 60' slightly quicker because you have a "running start" , so to speak. Reaction times will be slower all else being equal because you have a longer distance to go before leaving the beams. This is why it is critical to stage the car exactly the same every time when bracket racing.

So if you have a DONK you better leave on the top bulb.


I got treed on that one. :oops:

[DirkaDirka]

Ok what do you guys mean by roll out? Sorry I am a lil lost at the moment but not quite there yet. Also what does e.t. stand fer? What I am getting from this is that a taller tire will basically cause you to hesitate on the start. Sorry guys I am trying to learn. I dont know much about the track. Also what do you mean with breaking the beams?

[fla1976]

Roll out is the amount of time that it takes to break the beams. The bigger the tire the longer it is going to take for it to leave the beams. The beams are the sensors that are used to prestage and stage the car. When you roll forward the tire breaks the beam and the top amber light is illuminated. As you roll forward the second beam is the broken and the second amber light is lit. If you barely break the second beam then you have to roll further to unbreak the beam. A larger tire will remain in the beam longer so it appears the you haven't moved yet , but you are actually leaving already. Hope this is clear as it is easier to say than to type, especially if you a "pecker typer". :oops: :) Oh yeah, ET is short for elapsed time or the time it takes to run the length of the track. RT is you reaction time, or how long it takes you to leave after the light turns green. RT does not affect the ET. The clock doesn't start until the front tires are out of the beams.

[BEAST477]

Ok what do you guys mean by roll out? Sorry I am a lil lost at the moment but not quite there yet. Also what does e.t. stand fer? What I am getting from this is that a taller tire will basically cause you to hesitate on the start. Sorry guys I am trying to learn. I dont know much about the track. Also what do you mean with breaking the beams?

OK Dirka I'll try to help. If you took two pieces of string ran them parallel to each other say a 1/2 inch high and a 1/2 inch apart to simulate two beams of light. Now if you took a dime and stand it on edge it would just touch both pieces of string or both beams of light. Now if you took a quarter and did the same it would touch both strings or beams of light longer. Hence short tire vs taller tire. Taller tire stays in the beams longer fools the timing system a little where as you are moving a little and it can't tell till you move enough to clear the back string or light as it be.
ET is elapsed time or how long it takes to run the 1/8th or 1/4 mile. Sorry so long . Hope this helps.

[DirkaDirka]

OK I think I get it now. SO bigger tires will affect yer reaction time but not yer E.T. Except make yer E.T. a hair faster. So shorter tires are better on the front. Thanks alot for the info. Its alright to be a pecker typer. U sed to be one. Now I just got to quit looking at the keyboard when I type. LOL

[BEAST477]

Shorter tires are better on cars that react slower. If your car reacts quick you have a better chance of turning on the RED bulb more often.

[DirkaDirka]

Ok so you got to find that happy tire size for the car. Not to big and not to small so you wont keep turning the red light on. Ok I'm learning something new everyday.

[fla1976]

I'd say the most important thing is to be consistent. Try to stage the same everytime. You can adjust the delay box if you use one to bring the reaction time down to an acceptable level. But if you stage differently you'll end up red lighting and that's the end of the day for you.

[DirkaDirka]

Do you have ot run a delay box? If so what does it do? LOL Sorry I got to learn a lot. I didnt realize how much there was to learn about drag racin.

[fla1976]

The delay box is optional . In some classes it's not allowed. Basically it allows you to leave on the first amber in bracket racing. The lights go amber, amber, amber and green unless you leave early. If you leave early there is no green, only red. There is a half second between each amber. So, you have 1.5 seconds before the green. The reaction time of you plus the response time of the car is what you try to minimize. The delay box allows you to release the trans brake at the first amber and it waits the amount of time that you dial into it before the transbrae actually releases. This allows you to focus on one light, rather than three. If you stage consistently, you can be deadly on the tree. Hope this helps.

[DirkaDirka]

Oh this helps out alot. I dont hink I will run the delay box just for the fact that it aint allowed on some tracks or classes. Im pretty good at launching and i can time the launch pretty good. I went down a 1/8mi track in my celica using the tree. Never did get a red light and always got the jump on the guy in the other lane. So I just hope I can do the same thing with pros

[Tod74]

The reason a delay box helps is it is easier to react to the first flash you see rather than have to watch the ambers drop and anticipate it...plus with most delay boxes you can cross over and use the other guy's top bulb if you are faster...that way you KNOW when it's coming(just after you both stage) if you are faster than the other guy and his tree starts and your top bulb isn't on yet you never really know when it's coming...sorta.if that makes sense.

[DirkaDirka]

Yes it does help alot. I think I will have to actually get in a car with the delay box down the strip to get the feel for it. Just by how it is described i dont think I will be able to use it. I think I will get caught off gaurd when it decides to go and I will miss a shift. I hope I explained it good.

[I972Nova]

Here is an in car video to see a delay box in action...

http://www.youtube.com/watch?v=wR9-N0l9KOw

[FullTimeRacing]

I was running a 26 in tall tire and was red lighting -.020 or worse, went to a 28 in tall tire and now get .020 to -.010 light.

I'm able to leave on the third bulb in steed of having to pause. which is my gole

I'm a foot braker.