I've heard this too but it don't make sense... a balanced wheel is a balanced wheel.

I think what part of it means is if they had to install a second set of weights they missed the placement of the first set in the right location. Now they're countering with more unneeded weight to achieve the proper balance. I don't know if too much weight is needed in one area that tape weights can't cover, then two balance area's are used is a factor.

How much weight is considered to be too much?

When I had mine rebalanced I went from a nice row of about 8 small weights to 3 big clunkers on one of the wheels.

The shop I worked in always remounted the tire if they had more than 4.5-5 oz. in one spot.

Tires and wheels normally get balanced in two locations. One is done for both sides of the rim. On older steel wheels, the weights were placed on the outside edges, on both tire bead areas. With the newer aluminum wheels and the offsets they have, weights may b placed on both areas. One being on the inner edge of the rim and the other being on the outer edge near the spokes. These weight locations are normally not at the same clocked position nor are they the same amount of weight. The wider the tire, the more critical this balance is.

Just remember, every tire and wheel combo will be different. There should be only two (inner and outer) weight locations on any wheel that is properly balanced.

This explains why the guy at a tire shop that I watched got frustrated when he was balancing a tire....he applied the weight, spun the tire, applied more weight, spun, removed the weight, and started over. After three tries, he got visually pissed, removed the tire from the rim, remounted the tire, and started over. It appeared he finally got the tire balanced, as he removed it from the device and mounted it to the car.

Wasn't my car though!