I just purchased a set of C7 wheels from someone. Unfortunately, one of the tires was different from the rest. I therefore had to replace that one. I was told by the tire tech. that the wheel was not true, and could not be balanced completely. Can someone explain what this means? Can he be wrong. I thought the entire idea of the weights was to balance the tire to spin correctly? Please help?

John Cappuccilli

Unless he has a Hunter GPS 9700 balance machine, I don't know how he can tell whether the wheel is bad, or the tire is bad.

All wheels are not perfectly true.

And anything can theoretically balanced on a machine.

You could actually balance an egg shaped object on the wheel balance machines if you apply enough weights in the right positions.

However, even though the machine could balance it, you couldn't drive with it on your car, because you couldn't drive on an egg shaped wheel.

Check out the following website, enter your zip code to find a shop near you, and get it balanced there. It is the only machine that can identify your problem, and hopefully correct whatever is wrong.:

www.gsp9700.com

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

Thanks for the reply. There is a shop 3 miles from my house. I am going to take the wheel there. Can it be the tire that is bad. For example, if they tell me they can not correctly balance the wheel can I ask them to remove the tire and check the rim. That way, if the rim can balance I know I have a bad thread in the tire. Right?


John

Yes, the tire can be bad.

You may have a wheel force variation problem.

Check out the following thread I started that discusses this problem, and many other balance / vibration problems in excruciating detail:

Bad tires or bad wheel balance

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

If a wheel is significantly bent it is NOT necessary to have a GSP9700 Hunter balancer to determine this. The 9700 is masterpiece of technology and engineering, but a bent wheel can be seen wobbling when you spin it up on ANY computer wheel balancer.

The 9700 makes runout measurements easy. The runout measurement equipment is built in. You can, however with a simple dial indicator, perform such measurements.

If the wheel is bent so bad that it cannot be balanced, then I'm quite sure that it's bent bad enough that it is quite obvious to the casual observer when spinning on the balancer.

To answer the why and how questions, that's simple. The wheel may have hit a curb, came off of a car that was in an accident, etc., and etc.

There are shops around the country that can straighten a wheel, but thanks to the liability concerns via frivolous law suits, this has become EXTREMELY expensive. Your best bet is to buy a replacement wheel.

Best of luck,

If the wheel is significantly bent, then as Larry says, you're out of luck.

From viewing the Hunter website, I gather that the balance machine can balance each wheel's "roundness" to each tire's specific characteristics. In other words, I guess it tells the operator exactly where on the wheel to mount the tire to offset unevenness.

I'm sure that Larry is correct in saying that a competent operator can discern this for himself on other, simpler machines. I just think it's going to be quite hard to find a really good operator.

I'm sure we've all noticed that it's the kid just out of high school with little experience running the balancing machine...

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

suginami is correct about the typical operator. Although using a dial indicator is not rocket science, neither is using a computer balancer, but not very many people in the tire stores want to bother with doing it right.

If you do manage to find one of the tire stores that want to do it right, share the information with the rest of us. If they want to do it right, it is possible to diagnose the wheel as being bad without the magnificent machine. But, with the machine, they have a better shot at it.

Good luck,

Thanks for all of your help. I am taking my car to the shop on 5/15. The shop I am going to has the Hunter, and after reading the website I am anxious to have the wheel checked with the machine. I also phoned the shop and asked one of the reps the same question I posted. The first question he asked was who told me that. When he heard where I had the wheel done it laughed.

Additionally, after checking out the Hunter website, I wonder how many people are driving around on wheels that are not correctly balanced. The machine that the shop has that I will no longer be qoing to is a pile of junk compared to the Hunter. I am glad the shop is within a 2 miles from my home. I will let you all know how I make out. I might have all the wheels checked just to be on the safe side.

Regards,
John Cappuccilli

Again, I will try to explain how ALL wheels do not need the use of a GSP9700. IF the wheel is true, as most are, AND the tire is somewhat normal, as most are, a decent computer balancer with an operator with more than a fourth grade education that CARES about what he is doing can do a great job balancing your wheels.

Where the 9700 comes in to play is when you have a bent wheel, or more commonly a tire with excessive road force variation. In this case miracles can be accomplished with the 9700.

The computerized wheel balancers, most any of them, that started coming along in the early eighties are fabulous pieces of instrumentation. Most any of them, if properly used, will do an absolutely FABULOUS job of balancing most wheels. The problem is finding someone who wants to do a good job with the machine AND has more than a fourth grade education. These machines aren't rocket science, they just need someone that cares about doing a good job using them. These wheel balancers are NOT pieces of junk.

If you can find a shop that has someone that cares about doing a good job AND knows the difference between static and dynamic balancing AND will dynamic balance, they will most likely be totally successful balancing your wheels. IF, however, they are not successful, there is a good possibility that it is time to find the 9700.

One way to avoid the need for the 9700 is to put tires on the wheels that have been constructed with radially separated molds. This means that the mold marks on the tires look like pieces of pie instead of a mold mark all the way around the outside center tread (a clam shell mold.} The tires made in a radially separated mold have MUCH MORE uniform belt installation, are round, balance with much less weight and have uniform road force (minimal stiff spots.)

The only tires that I have personally seen that are built with this construction method are; Michelin, Continental, Yokohama and Pirelli. If you find any other brands constructed this way, please share this information with us.

Good luck,

who rolled you down the road at 800 to 1000 somersaults per minute and then kicked you every time you looked a little low???

Actually, way back in 1969 we got German-made computer balancers at Porsche dealers (Hoffmann?), complete with a special attachment for the bolt pattern of the Porsche mag wheels of the time, since they were not machined hub-centric, and I believe that the marvelous Hunter machines are built under the German company's patents.

Well, I just came home from the shop with the new Hunter machine. He lauged at me when I told him the shop said I had a bad wheel. He put it on the machine only to find the weights placed in the wrong place. He took the weights off, spun the wheel, and put new weights on. He told me the wheel and tire were in perfect condition. How can opinions vary like this. From a bad wheel from one being completely perfect. I am not questioning the shop today, but how could the other shop mess up such a simple job as balancing a tire. Oh! and I watched it myself. That Hunter machine, I believe it was the 9700, is amazing. It is like playing a video game. After the tech. took off the weights and spun the wheel, the screen had two arrows telling him where to put the weights and what size. He spun it again, and the screen showed that the tire was balanced. I wish all tire shops had that. I told the owner, he now has a new customer. Thank you all for your help. To think, the other shop had me buying a new wheel.

Regards,
John Cappuccilli

Yep, I suspected it was operator error.

Happy motoring.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

to get the wheel mounted out of whack in the arbor of the balancing machine with the hubcentric conical mounts, especially if the hub hole has been distorted a bit -- that's why years ago Porsche used to insist on attaching the wheels to the balancer by the lug bolt holes.

As suginami said it was operator error, or most likely, operator not caring.

Mounting the wheel can be done properly on any decent computer balancing machine. There is a flat faceplate that keeps the plane of the wheel perpindicular to the centerline. The cone only centers the wheel as it is pressed against the faceplate. If a particular wheel must be bolted in an adapter, it is not a conventional wheel. A conventional wheel centers on the center hole, not the lug bolts/studs. This is a problem you run into often with aftermarket wheels that center on the lugs, not a good thing.

For this particular problem that you dealt with, any decent computer balancer in proper working order is capable of doing the job, if the operator running it, gives a hoot about what he's doing. Any computer balancer will also tell you how much and where to put the weight just like the GSP9700 does. That's the basic function of the GSP9700 that is shared with any computer balancer. What makes the 9700 different, is its ability to measure road force variation with the pressure roller, as well as its ability to easily measure lateral and diametrical runout.

Again, this was operator error/poor attitude on the part of the first store you went to. Did they not have a computer balancer of any description? There are still a few tire stores here and there that try to get by with a bubble balancer or no balancer at all. You may have found one of them.

As I've requested before, if you find a tire shop that has a good attitude and is capable, you should share that information with us here.

Have a great day,