Track Tac

Tire Diameter Matter

racinnut15xm said:
Are you constantly having to blow the RS tires up through the week to keep them at 34? Or is the hot box I don't own the trick to getting them to 34 and keeping them at 34? Only ones that I own that stay at 34 are those treaded hoosiers I bought from you. My Vegas and my maxxis both shrink back if I don't put atleast 20pds through the week.
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Treat your burris's the same way maybe not 20lbs (i think i put about 16lbs in them) and if they leak down like mine you may have to top them off mid week. Fyi a hot box definitely is not the trick because i dont have one either this is how i heat my tires....
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racinnut15xm said:
Are you constantly having to blow the RS tires up through the week to keep them at 34? Or is the hot box I don't own the trick to getting them to 34 and keeping them at 34? Only ones that I own that stay at 34 are those treaded hoosiers I bought from you. My Vegas and my maxxis both shrink back if I don't put atleast 20pds through the week.
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Yes, on Burris, we usually keep 10-15# in the rights and leave the cores loose in the lefts. Our Vegas never shrink once they are heat cycled a couple times.
 
racinnut15xm said:
Are you constantly having to blow the RS tires up through the week to keep them at 34? Or is the hot box I don't own the trick to getting them to 34 and keeping them at 34? Only ones that I own that stay at 34 are those treaded hoosiers I bought from you. My Vegas and my maxxis both shrink back if I don't put atleast 20pds through the week.
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Some tires are definitely more of a pain than others.
I think the single biggest key is how the tire was mounted the very first time.
Certain tires have a "memory" to them, and will return to that first mounted size if left on their own. Hoosier slicks are certainly that way, so not surprising that their treads tend to be that way as well.

Burris are probably the worst for "keeping" their size, but the easiest to size.
Maxxis generally shrink unless you keep them up on air. Vega right sides will shrink some, but generally come right back when resizing them. (That is likely due to killing them with prep, making them soft, or the low air psi that we tend to run in them.)

Then, of course, you've always got the oddball tire that no matter what, never seems to size or stay right.
Generally I'd suggest that it was mounted incorrectly (ie took tons of air to bead up) or was made wrong at the factory (allowed to cool differently - taken out of the mold sooner or later than others, webbing stretched when inflated at the factory - who knows.)

No matter what brand you're on, you need to stay on top of sizing them all the time.
A hot box is not necessary, but it sure speeds up the process. A good afternoon of sunshine will work, as will a heat gun that is kept moving around the center of the tire.

There are several methods of sizing, but most will include heat, air, and time.
Shocking them in cold water afterwards helps "set" the size, but also rushes the cooling process and in turn can shrink the tire further.

Heat cycling your tires in an enclosed trailer all wekk long is resizing your tires whether you want to or not. That's why you hear some guys say that they put all their right sides up on air, and let the left sides down. While that may help, it's no guarantee that your tires will be sized correctly -- it's still going to be an issue of sizing them all the day before you go to the track (or even the morning of) and keeping track of them.
 
I myself like to keep my right sides at 34 1/4".
When the original post wanted to know if diameter mattered. I know the other year my brother had my nieces jr champ right rear at 36 inches. It basically make you have a taller gear. Then when after about 6 weeks when people caught on and 34 1/4 inch rule was put in place. So diameter does make a difference.
 
krtrcn said:
I myself like to keep my right sides at 34 1/4".
When the original post wanted to know if diameter mattered. I know the other year my brother had my nieces jr champ right rear at 36 inches. It basically make you have a taller gear. Then when after about 6 weeks when people caught on and 34 1/4 inch rule was put in place. So diameter does make a difference.
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Sounds like they had a gear rule?
 
krtrcn said:
I myself like to keep my right sides at 34 1/4".
When the original post wanted to know if diameter mattered. I know the other year my brother had my nieces jr champ right rear at 36 inches. It basically make you have a taller gear. Then when after about 6 weeks when people caught on and 34 1/4 inch rule was put in place. So diameter does make a difference.
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That point ( all though valid point ) is not comparing apples to apples to the OP question, at least the way I take it, as I think he's simply asking if my RF is 34" and my RR 34.5" but my stagger is good, will that cause me issues worth worrying about ?
 
Bandmn said:
Burris 33s... A friend of mine had a left side that i couldnt get to shrink to save my life.... Had a cooler full of ice water used almost a 22lb bag of ice type of ice water lol... Put tire on my surfacer and heated with a cutting torch like "i go to grow a tire" with the valve core out, slammed the core in amd submersed in the cooler put a piece of heavy steel on it to hold it under..... No luck
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I run 33's and I have put them in a kitchen oven and then ran them under cold water and they have shrunk a bunch.
 
CarlsonMotorsports said:
I think the single biggest key is how the tire was mounted the very first time.
Certain tires have a "memory" to them, and will return to that first mounted size if left on their own.
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So if you are mounting left side Maxxis tires, and you want them as small as possible. What is the best way to mount them. If you need them smaller yet, what is the best procedure to shrink them?
 
A properly sized tire band .
Clean rim .
Proper lubricant.
Warm tire .
Valve core out .
Good supply of air.
 
DrDave75 said:
So if you are mounting left side Maxxis tires, and you want them as small as possible. What is the best way to mount them. If you need them smaller yet, what is the best procedure to shrink them?
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Warm them up to 70* or warmer, and put them in a LF ring (32 1/2"). Use a 6 1/2" wheel, and lubricate the bead with your favorite tire mounting lube. I use our Green Apple Tire Clean to mount tires here in the shop and it works GREAT!
Take the valve core out, make sure that your compressor has the regulator turned up, or bypassed, and inflate the tire rapidly with a safety cli-on chuck and 6' quick release whip (hose.) As soon as the tire beads, uncouple the whip and let the tire deflate to flat. Remove from ring and inflate to race psi. That should do it.
If you need it smaller, then follow instructions on shrinking a tire found on this website.
 
racing promotor said:
That point ( all though valid point ) is not comparing apples to apples to the OP question, at least the way I take it, as I think he's simply asking if my RF is 34" and my RR 34.5" but my stagger is good, will that cause me issues worth worrying about ?
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One half inch more in the rear . Likely won't cause any serious issue . One inch may , especially in the front as its now going to affect chassis rake and transfer across the front . My belief is it will delay and hinder transfer across the front .
 
DrDave75 said:
Is there an advantage to using a ring instead of an adjustable band?
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Sure: Consistency, more rigidity, better roundness, quicker, no parts to wear out, etc.

However, they are limited to one size, whereas an adjustable band can be used for several sizes.
For the average Saturday night karter, adjustable bands are more practical.
To a tire guy, or a racer who mounts a lot of tires themselves, tire rings might be well worth the investment.
 
CarlsonMotorsports said:
^ What width wheel?

You shouldn't have too much problem shrinking a 6.00 Burris to 32 1/2"
To get one down to 32" takes some special effort.

As per the original question - keep in mind that all of our current chassis have been designed for 34" right side tires. This determines the chassis ride height, rake, and tilt.
A 34 1/2" tire will make minimal difference in the ride height, but it WILL make a difference (and how the weight transfers is different as well.)
I would have no reservations about a super heavy or UAS type package running a slightly taller right side tire, but keep in mind that even if CoG is raised minimally, it WILL affect the overall set-up and handling.
I prefer to have ALL of my right sides at 34" so that I can swap them around (front to rear) and grab anything in the trailer and not have to worry about it affecting corner weights on the scales. It really simplifies things for me.
Work on stagger by sizing the left rears and have an add'l lr tire or two in the trailer for when you want to try something different.


-----
🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
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31 years of service to the karting industry
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
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What is this easy process of shrinking an 11 to 32.5 i have about 6 that are 33.75 and cannot get them to shrink.. please help tha ks
 
Mulearacing said:
What is this easy process of shrinking an 11 to 32.5 i have about 6 that are 33.75 and cannot get them to shrink.. please help tha ks
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The process for getting most shrinkage is remove valve gut. Heat the crap out of them with a torch throw in a freezer for an hour, repeat if needed, your trying to shrink a lot ya might not get that much
 
A grill can work to, heat them in the grill, flip
Them half way through, throw them in the bucket with ice and hold until the wheel feels cold. Repeat if you need it to shrink more.
 
This really doesn't apply to karting because our tires are so small, but a bigger tire does actually put more rubber on the track. Look at F-1, Indy cars, most sports car series, and see why the tires and wheels are so large. More contact patch (even if it's a tiny amount}.
That said, karts are designed to use a 34 inch RS tire as Brian said and yes in small ways a bigger tire does upset things but for a Saturday night racer do what you need to do to make its turn. One thing about dirt racing, it's not often a perfect world.
 
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