Tyre fitment problems

[RichE]

When we got our Hoosier tyres fitted the bead of the spun rim was deformed by the tyre sidewall.
Has this ever happened to anyone else?
Is it the fault of the tyre, the fitter, or the rim?
In my opinion the rim was not sufficently strong/stiff.
What does everyone else think?

Rich

Cardiff Uni
FS Team Manager

[Frank]

"Is it the fault of the tyre, the fitter, or the rim?"�

The answer is probably a combination all of the above. But the fitter should have done things to help.

Have you seen how this happens?

Personally, I witnessed tyre fitment of this type for the first a few weeks ago.

Very different to street rims, spun rims usually have a (fairly) flat cross-sectional profile. When you lever (by machine of course) the tyre on, it sits in a very deformed shape. You then apply pressure and the tyre moves to its final position.

Thing is, as it moves to it's final position, it "snaps"� into place. It is a very violent process indeed. It whacks the rim HARD. The sound of this caused me to roar an expletive.

I think the "tricks"� are to

A Use plenty of detergent all over the rim when you apply the pressure to seat the tyre

B Don't use excessive pressure to seat the tyre, 25 psi should be enough. If it isn't then stop, apply more soap, try and wiggle the tyre a bit by hand, and then have another go at pressurising it.

C Be careful with the clamping mechanism on the machine, as simply clamping the rims too hard can bend ˜em

Regards

Frank

[RichE]

Hi Frank,
I watched it all happen, as the wheel is rotated by the machine the tyre sidewall is fed onto the wheel.
It pulls the sidewall of the tyre very tight and the tension in the sidewall was enough so that where the sidewall crossed the rim it deformed the rim. Once the tyre had been fed onto the wheel we didn't have much difficulty in getting it seated. But our problem was getting it on in the first place.

Rich

Cardiff Uni
FS Team Manager

[Sam Zimmerman]

At the beginning of last year we inherited eight deformed rims. The standard procedure the previous years was to take the rims to a tire shop to have them mounted.
When we bought our new rims the decision was made to never allow a tire shop to mount them. We mounted our tires by hand all last year and will continue to do so this year. Other than a few nicks, our rims are in very good shape. With lots of lube, taking your time, and some tender words you can keep your rims happier than any machine ever will. http://fsae.com/groupee_common/emoticons/icon_smile.gif
We can also get our tires changed out in much less time than it takes to drvie to the tire shop, wait around, and then drive back.

Sam Zimmerman
Vandals Racing (http://www.uidaho.edu/~racing)

[Alejandro]

Hi guys..

For last year car we order a KODIAK wheels. Besides of the measure errors they had, one set didnt have the flat cross-sectional profile (so they are like street wheels). Because of that we had big, but real big problems to fit the wheel. But we aply some of the strategies that Frank mention to solve the little problem.

"B Don't use excessive pressure to seat the tyre, 25 psi should be enough. If it isn't then stop, apply more soap, try and wiggle the tyre a bit by hand, and then have another go at pressurising it."

For all the tires that didnt have that flat profile the guy from the tyre shop aplyed like 60 psi!! yes, thats correct, and maybe more.. The guy from the tyre shop putted his self with his eyes barely opened while he pressed the tire pressure pedal. We remained behind a Ford explorer like 10 feets away until we hearded a strong clap. In that way we fitted the wheels.

We havent experienced wheels deformation. Even with this way of fittment. JEJE, not recommended.

By the way guys! Last week we run in a 100 meter track with a 350 hp (on the wheels) subaru and a Ferrari 348. It was an aceleration test and we bit them both by a car. It was really cool. The guy from the subaru never expected to be bitten by a little Formula SAE. you can see the pictures in the webpage.


www.formulasae.grupos.usb.ve (http://www.formulasae.grupos.usb.ve)
Formula SAE USB

Alejandro Rondon fsaealejandro@cantv.net

Alejandro Rondon
Fsae team

[Charlie]

It sounds like your deformation is not from the seating of the bead, but the installation of the tire on the wheel itself (before the bead would be set).

In that case, you can do like Sam and carefully put them on by hand. But it's not the machine's fault, it is the operator. You can control the amount of force you are putting on the wheel half. The trick in mounting is to have the bead well lubricated, and make sure the other half of the tire is well seated in the 'groove' in the center of the wheel. That's what the groove is for, installation.

I've mounted all our tires since 2000 my self, except for 1 set when the Goodyear store bent all four. http://fsae.com/groupee_common/emoticons/icon_redface.gif Car wheels are strong, so the methods most of the tire monkeys learn are some form of brute force.

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Jarrod]

WE at Monash have had some issues in fitting tires, in 2001, one of the 2mm thick 5005 rims got folded in half by the bead breaker at a tire shop, after that, fitted all tires by hand. The rims were way too soft, used to deform the outers while fitting tires by hand. Got a set spun up from 2.5 mm 6061 T6, much better. We have made a bead breaker that attaches to the floor in our workshop and our trailer, hand operated. I would never trust a pneumatic one on our rims. Race tire guys suggested no more than 40 psi, I think because of the rims.

[jerktaculus]

Do i have a story for you .. we bought 8 kodiak rims last year and no tire will fit onto them without ... 120 PSI !! .. we understand this is stupid but it was all about the time to get them machined .. so yeah we had to machine the lip that the tire seats on. Watch out for this .. maybe we were special. Half of the team has been exposed to pounding on a tire that looks like it is supposed to go on a motorcycle .. guess last year we had someone up there on our side.