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Author Topic:   Stretching American Racer's
flanndad#17
Member
posted September 14, 2003 08:26 PM
Somehow I stretch my left rear with gave me a reverse stagger on the rear end, and because of the offset's in the rims I couldn't just switch them.

Question is once a tire stretches is there any way to shrink it, i don't believe there is.

Or do you just go and them them remounted.


racer17j
Member
posted September 14, 2003 09:09 PM
once she is stretched out she is there for good a few guys do this on purpose something that they do that you might have not and not realized it is put alot of pressure in it and let it set in the sun any chance you had it aired up to set the bead and left it outside on the tire rack?


dirtrace54
Member
posted September 15, 2003 02:52 PM
Funny to see this topic...I just stretched some American Racer EC-2's last nite for my bother's late model. Put 'em on a rim and set'em at 40 psi for an hour. Most gain about 1/2 to and inch of circum.


dirtbuster
Member
posted September 15, 2003 03:41 PM
We have tried this on mod tires and the only way to keep a big tire big after stretching is to always keep it full of air. Put 50psi in it and stretch, then let it down to run, then as ssoon as it comes off the track back up to 50.

We have never had much luck in keeping them consistent. WE can stretch them but as soon as they run they seem to shrink back down. Or we will run a new tire and it will shrink the first time out.

Raz_900
Member
posted September 15, 2003 03:55 PM
We pump them (Hoosier HTOV RC4's) up to 50psi and leave them sit in the sun all week. That's usually good for about 3/4". Also, the tires that were left outside (covered) all winter in the shade were magically 1" - 1 1/2" smaller than all the rest. All the tires have maintained their size, minus wear, all year. I've been able to get some down to 84 1/2" - 85" and up to 87 1/2". They were all 86 1/2" - 87" when new.


fastow
Member
posted September 15, 2003 05:59 PM
quote:
Originally posted by fastow:
raz i never heard of leaving the tires out all winter do you know what happens to the hardness of the tires you leave out all winter compared to fresh ones. Also you guys all measure tires when you pick them out at the tire truck and what is the biggest\smallest tires been not aired and what do the air up to .


The tires are Hoosier HTOV RC4's so they're basically hard as a rock to begin with. The track is dry, hard slick almost all the time. I'm not saying it's the best thing to do, but it was surprising how much the tires 'shrunk' when they were left outside. It's happened to 6 tires over the last 2 winters. Really can't tell any difference in the traction of them versus brand new tires. We generaly have to grind the tread flat after 2-3 races on the right sides and that exposes fresh rubber that seems to be fine.

All the tires I've ever bought were within 1/2" from the factory. So we do what we can to get some stagger from them.




Mikey14
Member
posted September 29, 2003 11:32 AM
ok, first off I've never tried this with stock car tires but I have shrunk and grown kart tires to gain or lose stagger. Here is what I did to shrink and grow them.

Step one, give your wife/live in girlfriend $50 and send her to walmart. That way she'll be gone for hours. May require more or less (yea right) $$ depending on your wife/girlfriend.

As soon as she leaves,

Preheat the oven to 400 degree's.

To grow a tire:
Leave the valve in and tire mounted on the rim it and about 30 PSI.
Stick it in the oven. Yes I know it will take a big oven for car tires. 15 to 20 minutes in the oven.
While its in the oven fill a tank or tub big enough to hold the tire with ice water. LOTS OF ICE.
About now you'll need to open up the windows in the house to get rid of the smell.
When time is up, remove tire from the oven. Now this part is really important: Wear two long sleved shirts and use gloves! Shorts are not recommended either.
As quickly as you can, put the tire in the water and cool it off. Leave it in even after surface is cool as the insides are still hot. Let it soak for about 10 minutes.

To shrink a tire:
Take the valve out and keep the tire mounted on the rim.
Stick it in the oven. For about 15 to 20 minutes.
While its in the oven fill a tank or tub big enough to hold the tire with ice water. LOTS OF ICE.
About now you'll need to open up the windows in the house to get rid of the smell. Use a fan to get circulation going so the wife doesn’t get upset.
When time is up, remove tire from the oven. Now this part is really important: Wear two long sleved shirts and use gloves! Shorts are not recommended either.
As quickly as you can, put the valve back in and stick the tire in the water to cool it off. Leave it in even after surface is cool as the insides are still hot. Let it soak for about 10 minutes.

Garnish lightly and serve cold.

Get everything out of you house and spray deoderizer everywhere. Keep the oven open so it will air out too. No need to have your lasagna taste like dunlops.

I did most of this tounge in cheek but it does work for kart tires. I'd love to know if stock car racers have tried this too.

66jj
Member
posted September 29, 2003 12:58 PM
doing the above will make the tires a lot harder on the durometer.

basically your heat cycling them then cooling them, or curing them rapidly.

all tires shrink if left sitting, unless aired up. and preferably stored in a dry constant temp environment in a bag, they also get harder. allways.

tilley88
Member
posted September 30, 2003 12:57 AM
Mikey, keep postin. Your knowledge is invaluable. Don't let 66jj intimidate you, even tho he is smart and usually comes up with really good answers. But only second rate compared to mine(hic).


Mikey14
Member
posted September 30, 2003 08:18 AM
Thanks Tilley,

Maybe my way makes em harder... his way makes em harder too. Mine takes an hour or so.

Now if you want to soften them I've done that too. just takes the right cancer causing chemicals and a couple of rolls of paper towels.

I feel like McGuyver!!

Mikey14
Member
posted September 30, 2003 08:24 AM
BTW

I've never gained more than 6 points on a durometer after doing this. Again it was on a kart tire though.

Usually I go from a 48 or so to a 52. I can always soften a tire back down to gumballs.

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