D2585 Goodyears

[jspell]

Anyone running the D2585 slicks experience the rollout changing over time causing a mismatch?  At race pressure the set always taped darn near exact, now 1/2" difference. 

[dreracecar]

Big show Teams hand out tires for the indi's to scrub in, tire guy then takes those tires and match pairs them to be used during elim's.

 At our level 1/2" is not enough to worry about unless you listen to know-it-all people it the stands that have never owned a car. I buy a matched pair of "green" tires and put them on the car, burn them in and never once after that ran a tape around them, I cant afford to keep buying tires to match them up----It does not make any difference at our level, same goes with compound, after a couple of races and the sun beating down on them , they are all the same.

Racing does not have to be expensive--a racer just has to be smart about it

[jspell]

Thanks Bruce...I'm trying to solve a handling issue with my car...car ran each pass straight as an arrow...last 3 passes at different track location, car gradually is driving left?  That's why I was looking at stagger.  any thoughts?

[ricardo1967]

"... car gradually is driving left? ..."?

That's one if the problems when running V (or opposed) configuration engines... left and right banks are producing uneven power! Try taking some timing off the right bank...

SORRY

[coupemerc]

I have been using the 2585 tires and have not had any issues like you describe. 1/2" difference in circumference between the two tires would definitely concern me on a car as fast as yours. My opinion is 1/2" difference in circumference between the two tires would explain the car driving to one side. You may be able to "stretch" the smaller tire by over inflating during the week. It will be interesting to see what Jon Hansen has to say about this. I try to keep my tire pressures relatively equal at all times and mine are within 1/8". Make sure you are lined up straight and stay in the groove. Good luck!

[jspell]

Thanks Chuck...we'll keep working on it.

[dreracecar]

Since you have run a couple passes with the GY's , you can now swap sides without issues and see if it pulls the other way
 I have run tires with 1" stagger without problems, 1/2" is nothing.
Over inflating a tire to gain circumfrence is only temporary and will come back. We did it in sprint cars all the time, but we kept the tire hot by running it constantly, and by the end of the night it was worn out to the point that we did not run it again--we sold it to a rookie for fuel money the next weekend.
stretching a tire by air has its problems, you have to over inflate it and what happens if you go too much and the tire gets bigger than needed???
Again in what we do 1/2" of stagger might move the car over 12" over the entire run

[George]

I too match green tires but after that it's something I never check again. I'm not sure when a difference would become a problem on a long car? The question really becomes "what do the tires grow to during the run" ? That's a question that probably can be calculated but I'll leave that to the number crunchers.

[JrFuel Hayden]

I have not seen any tires that have changed roll-out after being run for a time.
The Goodyears I sell are matched by mounting, inflating them to 20 lbs and then lowering the pressure to 7 lbs, then measure the roll-out and mark them for matching sets. 
I have seen and raced with uneven roll-out tires by a liitle under 1" difference, because one of the matched set tires went bad in the trailer. So we put about 25 lbs in her and set out in the sun, ran the event by still using 1/2 lb difference in each tire so that she would go straight.
I would try swapping sides to see if the car goes in the other direction. If it does, try running the shorter tire with more pressure.
On hot sunny days we use tire covers to keep the tire pressures more consistant. Bottom line you want to go straight. Any chance you are racing at a track with a crown in the track ?
Good Luck
Jon 

[masracingtd1167]

It could just be the track itself or it could have been a little gust of wind . What track did it happen at ? when I run at Lebanon Valley my car allways walks to the left when I run the right lane . Not sure what your car weighs but I would think it is pretty light . I have no wing on mine and at 180 it's pretty good . When I was spraying it it went 193 and at that speed it was spooky ! I would take a good look at every thing and rotate the tires as someone mentioned . One more thing I know your car has rack and pinion steering . How short are the arms ? The shorter the arms the quicker the steering is and could make it a little touchy ! I hope this is helpful to you . Bill 

[jspell]

Hi  too.Bill,
Thanks for following up...I'm checking everything over now...Car has always been well behaved straight as an arrow, last two races MapleGrove and E-Town car moves left before the 1-2 shift...I've been playing with tire pressures too.  I'll keep u posted. 

[coupemerc]

Look at it like this...A D2585 tire makes about 160 revolutions in 1320 feet. If one tire is 1/2" in circumference greater then that tire is trying to go 80" (almost 7') farther than the smaller tire on the other side of the car. That will move the car over. Why wouldn't you want to make both tires equal?
Another thought...Do you have a shift button on the steering wheel? Some drivers tend to turn the wheel a bit when they punch the button.
Good luck. You'll figure it out!

[dreracecar]

Thats old school thinking, If we were running tires from the 60's that were hard recaps on a untreated surface, I would agree, but that little difference only shows up as a little more squat for the bigger tire. Look at the pics on line of a NHRA fuel tire all squared up. The diameter now for that tire is measured from the center of the axle to the ground which also gets displayed on the data loger from the hight sensor mounted at the rear end so they can calculate tire growth as the car goes down track--- thats all part of the clutch settings.

[masracingtd1167]

John I did not realize it was happening so early in the run . Check your wheelie bar.Make it is straight .That could make the car drive like you have said!

[jspell]

Thanks Bill...I'm on it now.