as my vibration now above 80 is still there (BUT MUCH BETTER) i had my tires balanced at discount tire previously a year ago..
i decided to spring for the forced balancing .. it was 99 bucks for all 4..
before i could pay he already said the one on the machine will NOT balance as there is too much 'hop' and would check the rest..
says he was able to get 3 OK but they still had some hop but should be OK.. said take them drive it and if no good bring back and refund balance.
I asked about buying one new tire he said just get 2.. ( i thought i had decent tread).. got them home noted 2 of the 4 tires had these markings on them an dassume the one with the biggest 'hop' they didn't even put weights on..so i decided to buy 2 more brown lettered BFTA..
will be in thursday and will return all 4 to pick worst ones..
i asked about the ok tires what was the hop pounds and he said worst 19.. i said that sounds high and he said up to 30 ok... beats me.
he actually showed me the out of round on the one tire, he was not sure if some treads let go or what..anyway will update.. hoping for 100% fix..

update- very interesting tech service bulletin on tires and vibration from GM... 18 pounds generally ok
https://static.nhtsa.gov/odi/tsbs/20...89121-2280.pdf

 

one new tire was 10 pounds on force balancing, and the other new one was 15 pounds after moving tire to get there.. they said they used to put red dots but these did not have them..
old brown letter tires were 12/2017, new tires were march 2022 and NO country of origin!!???
will see how white they stay...
edit…inside of tire made in Mexico

 

Remember back in the day when they did bubble balancing and somehow it was good enough



I keep wondering if all the "new" methods they keep coming up with simply allow the manufacturers to make crappier products knowing that they'll catch it on the install
M

 

we had one that was 2 cones on an axle. You spun the wheel until it stopped on the heavy spot, then added weights unitl you got it to disappear. Then it had an arm to spread out the weights. it worked reeallly well

 

I still use the "bubble balance" and it woks just fine. The main reason tire shops went to spin balancers was because it allows untrained monkeys to balance tires if they just pay a slight amount of attention to what they are doing. Static balancing takes some thought process to get it right.

 

Other than almost dying on road trip test from brake failure,
https://www.corvetteforum.com/forums...ying-79-a.html
i can report for the first time ever smooth zero vibration to 103 mph..the car behaves like new, not a truck..
i did have tires spin balanced prior..but not force balanced..
not saying its required but it diagnosed my issue..
Success ..

 

M

 

Front tires I balanced on the car by jacking it up and spinning the tire. It moved freely, rocked back in forth on the final spin, put weight on opposite side, top, slowly spun it. If it appeared balance I was done. Did this for year until disc brakes came along. Nothing too fancy on 50s, 60s cars. It worked

 

"Bubble" and/or "Static" balancing worked fine when tire & wheel combinations where under four inches in width, anything greater than that and one now has a "couple-imbalance" influence to contend with, which is only addressed in "Spin" or "Dynamic" balancing.

Scott.

 

That is the theory! My 10 inch wide Corvette wheels have no vibration at all using static balance. I balance a lot of tires for friends and family all using static balance and they do not have any vibrations. I do have a good static balancer. The last version that Coats made before they switched to spin balancers.

 

I'm sorry, but this is reality; and the fact that you even question such indicates you really lack the understanding required to properly balance any modern wheels.

"Static" balancing is truly only the "proper" process for items in rotation which are, or effectively are, only two dimensional (aka. a flat disk diameter); as soon as there is an additional dimensional plane (width) now you have the problem of where might the imbalance of the diameter held within that length? This is the "couple-imbalance" concern. Now when tires where only 3"-4" wide and the vehicles didn't traverse the topography at a great rate, who cared about the couple imbalance; but as the tires got wider and vehicles got faster now occupants began to notice that even though the tires & wheels had been balanced (statically) there was still a vibration (imbalance), hence the introduction of "dynamic balancing" processes, which was to address a couple value.

aka. Your 10-inch wide tire and wheel combination can be static balanced perfectly, but if one were to check the couple balance value it could fail miserably. And as for your stated experience of apparent successes in your balancing efforts, well, like it or not, I'd have to label that as simply the "luck of the draw" of that of which you happen to have been working with, or perhaps just who.

For those that still need additional evidence consider driveshaft balancing, as this process is solely a couple-balance process, and is executed with the placement of correction weight being added at each end, not a singular correction in the middle.

Scott.

 

I did not say I question the physics of dynamic balancing. I only question the relative benefit for most tire and wheel combinations. Comparing a driveshaft balance to a wheel and tire balance is laughable. I also did not say I just put weights in the middle of the wheel. I use good judgement and technique to place the weights where they are best suited for the particular tire / wheel combo. For example I put the bare wheels on the balancer first and mark the heavy spot. If that spot happens to be where a TPMS sensor is located (which it is a lot of times) I place the balance weights near the outer edge of the wheel so as to offset the not centered weight of the TPMS sensor. I then align the light spot of the tire (which is marked by a yellow dot on better quality tires) with the heavy spot I previously marked on the wheel. This keeps required balancing weights to a minimum.

If the bare wheel is well balanced, then I will center the balancing weights in the wheel so as not to create a dynamicaly unbalanced condition.

If I get by simply by luck, I must be the luckiest man in the world since I have mounted and balanced over 250 tires over the past 6 years. I have had only one set of tires/wheels where I tried to balance them and they required a ridiculous amount of weight so I suggested that owner to take them to a tire shop and have them dynamically balanced. Those were cheap crap tires and I would have needed over 4 ounces of weights to balance them. My normal balances typically require less than 2 ounces of weight.

I also question the skill of the shop people using spin balancers since they screw it up all the time. I have so many wheels come in with weight placements that are nonsense. For example I see cases where equal weights are placed 180 deg apart - both on an inside edge (or outside) edge. That does nothing for static or dynamic balancing. I am not talking about one inside and one outside 180 deg apart which would be expected to correct a dynamic problem. My guess is the person put the weight in the wrong spot and then when he spun the wheel to check it, the machine told him to put another weight opposite the first to fix it instead of removing the incorrect weight.

So do you have actual experience balancing tires, or do you come on hear telling the world I am wrong based on what you read on the internet?

 

In our machine shop, we own, and I operate (this for several decades), an industrial hi-speed balancing machine, where I spin-balance mostly automotive crankshafts, but also have been involved in many other types of items as balancing projects in an effort to solve vibratory problems; these often being brought or referred to us after unsuccessful attempts were made elsewhere. And yes this has included wheels for race cars where the rotational speeds are greater and the accuracy of them in balance as received has proven unacceptable. And although I have spun tire & wheel sets we don't "balance" tires & wheels like the tire store; this as first it just takes to much time for the set-up on our equipment, and few customers require this effort or superior result (but some have), but also at the level of observational accuracy we have available, one quickly establishes that a tire is not "truly" balanceable (though technically there isn't such a thing in absolute), this if only because it is not rigid and does not maintain a singular dimensional shape therefore it's mass is changing position at different motion velocities.

As far a questioning the local tire stores' quality of workmanship, I totally agree, and I would say one's chances of receiving anything close to that which one should and rightfully be expecting is pretty slim! My own personal experiences have led me to the decision that on my F350 dually, the last several sets of rears mounted I've requested that the tire store NOT balance them, and I'd swear they rode better than when they did put forth the effort in balancing!

Yep, I know, just "luck of the draw"! But so far.....................

Scott.

 

I would love to see your machine shop and the crankshaft balancer! That kind of equipment always grabs my interest.

So, it sounds like we are closer to agreement that static balancing can be an effective tool for tires - even wide ones. As you point out, a tire and wheel assembly is never going to be perfectly balanced. So it comes down to getting it balanced well enough that at the speeds the car is used at the driver does not perceive any vibration. No steering wheel oscillation, no noise or vibration that changes with speed, etc. And my experience is that I need to do a static balance within 14 grams and the driver will be completely happy. My balancer is accurate down to 3.5 grams (1/2 of a 7 gram stick on weight). I do not even have to get that close. If I am within one 7 gram weight, that is pretty much overkill.

Some of my friends track their Corvettes so they see sustained speeds of over 150 MPH on wheels and tires that I static balanced and there are no complaints of vibrations.

Since I do not have to be absolutely perfect and still have no vibrations, is a true and properly done dynamic balance going to be better? Technically it will be "better" but since it does not provide any performance benefit, I would say it is not really better. In some cases where a lot of weight is needed, I can see that a dynamic balance would be necessary. We could try to do the math but it would be over most peoples head to demonstrate the forces involved with a certain amount of weight off axis. If I find a tire / wheel combo that needs more than 4 ounces of weight (that is sixteen 7 gram stick on weights by the way) I will send the owner off for spin balancing. As I said, I have only seen that one time.

 

I have also frequently gotten by with just bubble balancing on wide race tires, for 40 years, and they were silky smooth to 150mph.
However those are high quality high performance tires to start with.
Yes they are just made better.
And they have more consistency and less balance issues and use less weight.
And many times bubble balancing is enough.

I have also had enormous trouble with less expensive, T-speed rated, or cheap tires, yes even including the BFG Radial TA.
They are just not made as well.
I have rarely seen more than a few ounces of weight on a top notch Michelin tire.
I have seen 10-12 oz or more on one tire on less expensive tires.

And one thing I have had lots of trouble with, that I have not seen mentioned in this thread, except briefly in the excellent GM bulletin above, is Tire or Wheel Runout.
I suggest checking every single tire/wheel visually on the spin balancer looking for "wobble".
You can even do it on the car, just spin the tire in the air.
Re check with a wire pointer if necessary. Point it at a wheel edge, or the edge of a tread block.
Wheels get bent. Under 1mm is perfect, over 1/8" causes problems. I have seen up to 1/2" wheel runout. 1/4" is kind of common.
They need to be true. Most can get straightened, whether steel or aluminum.

The same goes with tire tread runout. I have seen 1/4" tire tread runout side-to-side or up-and-down very frequently.
No amount of balancing of any kind is going to give that tire a silky smooth ride.
This usually happens only on the lesser expensive tires. And BFG T/As and Coopers both suffer from this regularly.
The cooking process when the tires are made is just too inconsistent. Unless more time (& costs) are spent.

At my local Corvette Shop we recently sent back 8 C3 tires that would not balance no matter what.
Every time they balanced them, and then re-ran them, they changed and then needed more weight. WT*??
They would not stay balanced.
Even after 6 tries in a row.
They had never seen this in 37 years!
They checked them with a pointer and the tire tread runout was near 1/2" both laterally and vertically.
The heavy steel belts were still moving inside, they were not cured properly. All eight were made the same week, and got warranteed by the tire mfgr.
The next set was virtually perfect.

Buy better tires and you don't have to deal with this.
But that excludes all currently available 15" tires.

I'll be running 18" Michelins on my C3 for this very reason, among others.

BTW I have never, or needed to, road force balance a tire.

All you can do, with BFGs or Coopers, is to have the tires checked for trueness on the spin balancer, and ask for another set if they are not. If they are not true, do not accept them. Check before you even leave the store. They just vary.