Alignments, Tires and Balance

By Dave Trux

More than once a week, we get a customer asking for an alignment. When probed as to why, more often than not the answer is, “My car is shaking at xyz speed.” The simple answer is that an alignment will not cure a wheel shake. As technically advanced as a BMW is, the effects of an alignment are still the same as any other car.

What an alignment will cure is uneven tire wear and in some cases a pull to one side. There are 3 major alignment adjustments: camber, caster and toe. Of these, only two will cause tire wear and only one of them will cause a pull.

Camber and toe will cause tire wear in very distinct patterns. Caster will only cause a car to drift to one side or another.

Toe is how much of a difference there is between the tread in front of and behind the tire. If the wheels are toed in, the tires will wear on the outside inch or so and across the tire you’ll encounter a fish scale effect. If the wheels are toed out, the tires will wear on the inside inch or so and across the tire you’ll encounter a fish scale effect.

/ \ = toed in

\ / = toed out

Balance issues and loose front end parts are what cause a car to shimmy or shake. Typically, if the car shakes at a certain speed and then goes away, it’s either an out of round tire or loose front end parts. The wheel, at that certain speed will reach its resonant frequency and begin to shake. When you increase road speed, the resonant frequency is passed and the shaking goes away.

A shake that begins at a certain speed then gradually gets worse is most likely the common wheel balance issue. If the tires are in good shape, we spin them up and re-balance them properly. BMW’s are finicky when it comes to alignment and balance issues. It’s why we have invested in only the best Hunter alignment and tire equipment. We do not farm any of it out as our desire is to deliver the car in perfect condition. We simply do not trust a “tire shop” to align one of our customers BMW’s.