Originally Posted By: Nick1994
... have watched them balance them 2 of the first 3 times, then yesterday I couldn't see them do it because they took the tires to the back and "Road Force" balanced them. They said only 1 tire was 1/4 of an ounce out of balance. I asked him if they still shake what to do and he said to bring them back and they might put Michelins back on the car (which I'll never let happen).
You can " balance..." a square wheel... it will spin on the balance machine and show as balanced, but it obviously won't roll smooth...
Same thing with tires, the wheel/tire assembly can be "balanced..." , as in show zero's on the balance machine, but not roll smooth. Road force variation is the most common reason a tire vibrates.
Balancing a tire is a simple operation... with modern balance machines, scewing up a balance job is hard. The machine tells you where to put the weights... then you do a final spin, and see if it shows zero's.
And a shop that has tried 4 times to balance a tire is missing the key point... it's not the "balance..." that is the problem, it's something else...
If a tire vibrates after balancing, do the following:
Leave the weights ON, and spin the wheel again. If it shows as balanced, or very close, then chances are the balance is fine, but roadforce or out of round is the problem. And I did some experiments with balance on a previous car, seeing how out of balance a tire needs to be to vibrate. It took more than 1 1/2 oz to start to be very noticeable... a 1/4 or 1/2 oz was imperceptable, at least on that particular car... (Acura Integra...)
Too many shops get the wheel, rip off the weights, and balance the tire again... and sometimes again and again....!
Roadforce balancing works very very well, IF... and that's a big if, the technician understands what the issue is, and knows how to use the machine, AND takes the time to PROPERLY match mount the tires. This involves spinning the tire, and measuring for rim runout and tire variance. Then breaking down the assembly and rotating the tire as per the machines instructions... then "balancing..." the tire, while also measuring road force variation. A correct roadforce balance takes 2 to 3 times as long to do as a "regular..." balance job, so many shops only roadforce balance on comebacks... if they have a roadforce balance machine at all.
Old school is to leave weights on and spin the tire... if balance checks out, THEN remove the weights, break down the tire, rotate it 180 * , and rebalance... this often takes care of the vibration issue. You have about a 1/4 chance of randomly getting the stiff part of the tire mounted at the high spot of the wheel. This often leads to vibrations that no regular balance job will ever fix. Then the customer blames the tech, but the tech is doing exactly what the machine says. Then the tech blames the car... or the tires, or something. Then customer goes to a different shop for a "better.." balance job, and gets the same vibration... frustrating and a waste of everyone's time...!