lobewiper

Went to Discount Tire for a balance check due to apparent return (after 11,000 miles) of minor shimmy. After balancing the first tire on machine 1, on a hunch I asked tech to see if machine 2 ( the famed Hunter 9700) would also indicate perfect balance. However, the Hunter indicated about three quarters of an ounce out of balance. I then asked him to see what their final machine (#3) would indicate, and this third machine also indicated out of balance (I think half an ounce static and one ounce dynamic), but in a different way than machine 2 had indicated. At this point, I asked the tech to balance all 4 wheels on the machine he felt was the most accurate, which was machine 2. I then went to another Discount Tire store and asked them to check all 4 wheels (yes, I have the lifetime balance deal). I asked the tech at store 2 to use their Hunter, but he was unable to zero it out (calibrate it), so he used one of their regular machines after rezeroing it out. Result: two of the four tires indicated that they were perfectly balanced, so no changes were needed. The other two were out about half to three quarters of an ounce, so I had them rebalanced. The shimmy is almost gone now. My point: If even the balancers in the same store disagree, what hope do we have of knowing whether balancing has been done correctly?

shadowfox777

I wonder how often these tire stores have their balancers calibrated (if ever)??

If the machines do get calibrated (such as on a monthly basis or something) maybe ask when they've been last calibrated. I'm guessing that they have a outside company come in to calibrate their machines.

lobewiper

Actually, the calibration process is quite simple. They screw a small round balancing spindle (weight) into holes drilled into the round metal disk that the tire fits up against, and then run the machine briefly. They do this four times, placing the spindle in each of two disk holes, once on the inner and once on the outer disk surface, and then the machine resets itself to zero. I didn't know this until yesterday, when I watched the entire process. I know they calibrated at least two of the four machines used--not sure whether these two were the ones used to achieve final balance, but I believe that they were. So, asking them to check the calibration prior to balancing is probably a good idea...

AuAltima3.5

I am going to say that in TN they never calibrate these things. Everywhere I go they can't properly balance a freegin tire. Three sets of new goodyears, one set of general tires, and one set of kuhmos and they vibrate at some point. Usually around 55. These tires were on about four differnt cars. Unbelievable.

SLuxury

I give up on the shimmy problem until I buy a new set of tires. Probably some Yokohama Avid H4S... anybody have first hand experience with these tires?