25" versus 29.5" front tires

[Mike Gaines]

Ok, we all know that 25" front tires will show a quicker reaction time on your time slip....but...
DOES IT REALLY MAKE A DIFERENCE...
I will explain my statement (Does it really make a difference).
If I have a 29.5" front tire and my opponent has a 25" front tire and it is a heads up race AND WE BOTH LEAVE AT EXACTLY THE SAME INSTANT.
1) I know he will have posted a quicker reaction time on the time slip because his shorter front tire connect the "beam" before my taller front tires connect the "beam"
But....if we both leave the start line at the exactly the same time the front of our tires are equal.
2) And...if we both hit the finish line stripe at the exactly the same time (the front of the tires trip the finish line lights we would have exactly the same ET and the race would be a tie.
3) Now...it is agreed that he would have a better "reaction time" but it would not a difference...

Please tell me how I am wrong with this thinking.
4) Is the only benefit of a better reaction time if you are in a bracket race and they are setting the "ladder" by the reaction time

is that the 25" front tire will be further up the ladder ???​

Second question:
I personally think that the 29.5" tall front tire helps a racer NOT to red light because it takes somewhere around .050 seconds MORE for the red light beam to connect.
Thoughts on this ??

 

[Crider]

Taller tire will also post a slightly quicker ET because the car gets a run at the starting line thanks to having more tool out. But in a bracket race it really wouldn’t matter

 

[Darter6]

I'm all for tall fronts.It helps me from red lights.Just too quick on the draw. My wife complains about that too.....

 

[NOSTRT980]

I too prefer a taller tire. I have them on my dart and coronet.

 

[dvw]

It's ET plus R/T that gives the total package. The clock starts when you break the starting line beam. R/T is the time it takes the car to break that beam AFTER the green light has come on. You add the 2 numbers together for the total package. Doug

 

[Frustration]

Mike, Remember, you start the tree (record your reaction time) when the rear of the tire leaves the beam...not when the front starts to move. Taller tires take longer to leave the beam, and that's why shorter tires are said to react quicker. Assuming you're running a full tree, you can make up for the difference by leaving earlier with tall tires. We run 29" tall front tires because they look better on our big B-Boooty...Body cars. That said, I can still go red, but have practiced (with a practice tree) to train myself to be consistently on the green side. If you're running a pro tree, you may want to use the shorter tires. When I run a pro tree, I leave as soon as I see the yellow flash. With a tall tire, that will put me at .030-.040. Shorter tires will put the same reaction time at .020 or so. I hope this helps.

 

[not so famous bob]

Mike, Remember, you start the tree (record your reaction time) when the rear of the tire leaves the beam...not when the front starts to move. Taller tires take longer to leave the beam, and that's why shorter tires are said to react quicker. Assuming you're running a full tree, you can make up for the difference by leaving earlier with tall tires. We run 29" tall front tires because they look better on our big B-Boooty...Body cars. That said, I can still go red, but have practiced (with a practice tree) to train myself to be consistently on the green side. If you're running a pro tree, you may want to use the shorter tires. When I run a pro tree, I leave as soon as I see the yellow flash. With a tall tire, that will put me at .030-.040. Shorter tires will put the same reaction time at .020 or so. I hope this helps.

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
This is right on. Also the taller tire will trip the lights on the other end a little sooner too, might even out the longer reaction time on the starting line, maybe 6 one way, half a doz. the other !

 

[69 GTX]

The only time this would matter in my eyes is when running without a delay box, or a pro tree. Pro tree you want to react as quickly as possible as most cars can't red light on a .4 pro tree. I had a guy at my track that ran a no box class and always had 2 sets of front tires 26 & 28 he used it to help his lights. If he was to quick on the light he'd put the 28s on and be good.

 

[gtxracer]

I'm all for tall fronts.It helps me from red lights.Just too quick on the draw. My wife complains about that too.....

I also lean toward the taller front tires, for the roll out. Come on Darter, stop whining and breathe slower!
Bob

 

[Mike Gaines]

It's ET plus R/T that gives the total package. The clock starts when you break the starting line beam. R/T is the time it takes the car to break that beam AFTER the green light has come on. You add the 2 numbers together for the total package. Doug

So...if the ET clock starts when you break the starting line beam....then "if" you just sat there and didn't move, the ET clock for your run would NOT start ? But the reaction time clock would start when the light turned green ?? So...if you sat there for, let's say, 15 seconds and didn't move at all then your reaction time would be 3 seconds, then you left, broke the start line beam and made the run at 10.00 flat then your time slip would show a 10.00 second ET and a 15 second Reaction time ??
Can you see why I am continually confused ?? lol
After the above questions are answered it would really help me figure this out.
But...My original question is " If both cars leave the start line at EXACTLY the same time AND both cars HIT THE FINISH LINE AT EXACTLY THE SAME TIME....wouldn't the 2 racers tie...and...if so...a tall tire which records a slower reaction time would NOT HURT THE TALL TIRE RACER IN THIS SITUATION ???

 

[NSS Guy]

I think the better question would be how is that 3400+lb car going to handle with the 25" front tire?
I know we aren't road racing but... that's a lot of weight on a small 25" tire, especially after a wheels up launch.
What's the thinking on this?

 

[Frustration]

If both cars left the line at exactly the same time, and had the same dial in, say 10.0...then they both crossed the finish line at exactly the same time...assuming a dead-on 10.0, the car with the taller tires would have broken out. The reason is his reaction time would have been slower due to a taller tire with more roll-out, causing the reaction time to be slower than the short tired car. Think of the reaction time as how long it takes your tire to roll through the beam. As stated earlier, the taller tire car would typically run a faster et, as it would get a head start (starts rolling before the reaction time is recorded).

Think of it this way...you are trying to have a run with as little margin for error as possible. Assuming you can make your car run dead on with a zero (10.000), the error margin would be exactly what your reaction time is. If you cut an .030 light, you would have left a .030 second gap that your competitor would have to beat in order to win. Let's say he was also dialed in at 10.00, but he runs 10.030... If he cut a perfect light (.000) the two runs would technically be a dead-on tie. PM me if you like and I'll give you my phone number to help explain it a bit better with more detail. I love that you, being an x heads up racer are learning to bracket race. It's a fun game, but it's a numbers game. The better you know the game, the better your chances to win.

In bracket racing, it's important to know what your car will do on the run before you make it. It's not important to run as fast as your combo is capable of running. Keep good records, and do not change anything on race day, except the number on your window!! Good luck.

 

[NSS Guy]

Ok, we all know that 25" front tires will show a quicker reaction time on your time slip....but...
DOES IT REALLY MAKE A DIFERENCE...
I will explain my statement (Does it really make a difference).
If I have a 29.5" front tire and my opponent has a 25" front tire and it is a heads up race AND WE BOTH LEAVE AT EXACTLY THE SAME INSTANT.
1) I know he will have posted a quicker reaction time on the time slip because his shorter front tire connect the "beam" before my taller front tires connect the "beam"
But....if we both leave the start line at the exactly the same time the front of our tires are equal. If you leave at the same instant and you have a .000 he will red light
2) And...if we both hit the finish line stripe at the exactly the same time (the front of the tires trip the finish line lights we would have exactly the same ET and the race would be a tie. Not always true, finish line photo eyes are 5" above the ground. Suspension or body work can trip the light, especially if hit the brakes and dip the nose..
3) Now...it is agreed that he would have a better "reaction time" but it would not a difference...

Please tell me how I am wrong with this thinking.
4) Is the only benefit of a better reaction time if you are in a bracket race and they are setting the "ladder" by the reaction time

is that the 25" front tire will be further up the ladder ??? Bracket race ladder? You might get the bye if there is one. Once, one round. ​

I personally think that the 29.5" tall front tire helps a racer NOT to red light because it takes somewhere around .050 seconds MORE for the red light beam to connect.
Thoughts on this ??

Leave the 25" tires to the guys that race on a .400 pro tree.
You should be able to adjust the car to hit a good light on a .500 full tree. Lots of options that are free: rear tire psi, stiff sidewall tires, stage rpm, footbrake brake psi, stage the same everytime, etc. Maybe Doug W. can chime in on some of his tricks.

 

[bwheeler051]

NSS Guy brings up a very good point. I can tell you that my 66 coronet drives better down track with the 29 vs the old 27.5. I didn't notice it until I got to a windy track like Atlanta last April with 20+ mph side winds.

DVW, do not give Jim Guy any tricks. I had a front seat view of just how good he is last year.

 

[6PKRTSE]

I personally like a 25" tire better just to keep my ride height lower how I like it. Never really ever had any issue with red lighting since a Pro tree anyway. It does create some oil pan header issues at times. Now with my new flat bottom Dragster pan with the tubular K-Frame I don't have this issue.

 

[not so famous bob]

So...if the ET clock starts when you break the starting line beam....then "if" you just sat there and didn't move, the ET clock for your run would NOT start ? But the reaction time clock would start when the light turned green ?? So...if you sat there for, let's say, 15 seconds and didn't move at all then your reaction time would be 3 seconds, then you left, broke the start line beam and made the run at 10.00 flat then your time slip would show a 10.00 second ET and a 15 second Reaction time ??
Can you see why I am continually confused ?? lol
After the above questions are answered it would really help me figure this out.
But...My original question is " If both cars leave the start line at EXACTLY the same time AND both cars HIT THE FINISH LINE AT EXACTLY THE SAME TIME....wouldn't the 2 racers tie...and...if so...a tall tire which records a slower reaction time would NOT HURT THE TALL TIRE RACER IN THIS SITUATION ???

If , all things are equal, (E/T/ MPH, and the taller tires car adjusts his leave for the longer roll out where their reaction time was the same, he would trip the finish line beams first.
A little food for thot: in a hemi superstock car, I had to anticipate the light a bunch, was a " big heavy auto.", A 2440 pound vega, I could redlight all time if I wasn't very careful, to the point of being slow on the tree. MORAL OF STORY, LITE CARS MOVE QUICKER THAN HEAVY CARS !

 

[66Satellite47]

Mike, reaction time is reaction time. Pick the tire you are comfortable with. Back in the day I ran both the 7.10 and the 5.50 Moroso fronts on my '65 Coronet. I got more comfortable with the short tires. You still need to leave on time, whichever front tire size. Keep up the great racing.

 

[Mike Gaines]

Well, after getting some real expert explanations on front tire size, roll-out, etc, etc. from our fellow racers here on B-Body Site,I am going to do the following:
1) Buy a pair of 25" front tires.
2) Go racing
Thanks everyone for your input.

 

[66Satellite47]

Mike be sure to tell us your experiences.

 

[hemiman426]

25" tire is good for index with a trans brake,smaller tires will gve you a good light,but your walking a fine line,if you go back and look at all old drag car photos they had big tire for roll out,ask the experts like bret kepner on facebook that adjust his reaction times with tire pressure,but depends how your car is set up,a lot goes into reaction times,how you react to the tree,front tire size,how the front end lifts up or on a wheelstand if pulls the front wheel out of the beams,raer end ratio,rear tire size,convertor,most of all how you stage and where you put the ire everytime,might be up to 50 things that goes into reaction time,