Reaction time difference, bias ply vs. radial slick
 

Anyone tested reaction times on their car bias ply slicks versus radials? Naturally one would assume the radials would be quicker because of more air pressure and a stiffer sidewall,no wrinkle, but how much??? Remember I'm talking R.T not E.T. thanks

Re: Reaction time difference, bias ply vs. radial slick
 

Tim, I saw nothing you could measure in RT, I guess it depends on how much air pressure you run in the bias tires. The travel distance to hit the tree is minimum so it can't be that much if you are consistent in your launch. The 60 ft's are about .03 to .04 slower depending on the time of year. Hope it helps.

Re: Reaction time difference, bias ply vs. radial slick
 

With my car, I gave up using biased tires to help slow it down. I'm not good enough to adjust my driving for the change.

A lot of added weight effects mine too. Took 200 lbs out for first round of class at Indy, went red. Put it back in for eliminations. Thought it was a fluke, until I duplicated it later testing. Guess I need to buy a Just in Time button. Don't have any spacers to pull off my Biondo button.

Re: Reaction time difference, bias ply vs. radial slick
 

Easy to do with a third pedal Ed.

Re: Reaction time difference, bias ply vs. radial slick
 

Sure be a lot more fun. I'm not up to the extra work.

Re: Reaction time difference, bias ply vs. radial slick
 

Keeps your joints limber.

Re: Reaction time difference, bias ply vs. radial slick
 

Re: Reaction time difference, bias ply vs. radial slick
 

Thanks Joe and Ed. Anyone else ?

Re: Reaction time difference, bias ply vs. radial slick
 

Zero RT difference between bias @15 psi and my radials @ 24psi. Radials are .10-.15 faster ET in my 12 second car. Your mileage may vary. .

Re: Reaction time difference, bias ply vs. radial slick
 

Mine would not come close to hooking with 15 in the bias tires. 9 or 10 for mine.

Re: Reaction time difference, bias ply vs. radial slick
 

Here is a bit of information on what effects rollout/reaction time. Weight is a huge factor. Front tire size is also important.

http://www.portatree.com/page--Tech-Tips--TechTip1.html

Happy Holidays!

Re: Reaction time difference, bias ply vs. radial slick
 

I am excited about Mickey Thompson's new line of smaller radials so I am really anxious to see how much it changes my RT and ET. I always ran 20lb in my bias ply slicks so I'm wondering if it will really change much.

Re: Reaction time difference, bias ply vs. radial slick
 

The Gremlin is lobbying me to invest in a set along with a set of rims since I didn't know about the 26 inch radial till today! Gremlin also runs 20-2 lbs, but I could see running 30lbs in the radial with ease. Tire weight increase is around 5lbs a piece for the radial versus bias.

Don't know how it would affect RT in a beast like the Gremlin, might slow it down dead hooking into a crowd pleasing wheelie of say a couple of inches, vesus the pro-stock style launch it sports with the bias.

Whats the best equipment out there for measuring vehicle reaction time currently?

Eric

Re: Reaction time difference, bias ply vs. radial slick
 

The best equipment is your time slip and the best fix is seat time, lots of it.
A practice tree will tell what your RT is. The rest is in your car. The average foot brake racer is .20-.25. Button boys are a bit quicker.

Re: Reaction time difference, bias ply vs. radial slick
 

Ed & Charlie, I run 18 to 20 lbs in my bias depending on the track conditions.

Re: Reaction time difference, bias ply vs. radial slick
 

Is it still generally considered to not use a radial on a stick car and that they should be left on automatics? What makes me wonder is that with some of the small converters along with the high launch rpm and leaving from a trans brake they leave like a stick car. Hard. This should also apply to the reaction time question asked.

Re: Reaction time difference, bias ply vs. radial slick
 

Joe, mine is an SS car leaving with a Trans brake.

Re: Reaction time difference, bias ply vs. radial slick
 

Eric, Lebanon Valley Dragway has a vehicle reaction time setup that will tell you roll out. You have to mount a module to your car, and then an extra sensor that they have on the track will calculate the roll out of your car. It prints on the time slip. That is the most accurate way to determine the roll out.

Re: Reaction time difference, bias ply vs. radial slick
 

It would seem that way, but the autos still are a fluid coupling, and don't hit the tire as hard initially. I have always had stick cars and the only time that I have used a radial was years ago when my Camaro ran L or M/S and I had a lot of wt and less power. It still loss in the 60 and 330 times, but made it up on the big end.

If there is any rt dif between the bias and radial, it certainly changes with the tire pressure.