When there are heavy spots on the tire and wheel that cause it a bit of wobble, your wheel may need balancing. Balancing adds weights to the wheel to balance it out. Now, we are talking about very small weight differences. Variations in the tire and wheel manufacture can cause a slight imbalance. The valve stem, and now the tire pressure monitoring sensors in the tire, also play into the equation.Learn more at NAPAautocare.com/preventative-maintenence/
Even small differences can cause annoying vibrations at speed: the wheel is essentially bouncing a bit as it goes down the road. For example, at freeway speeds, an out of balance wheel can be slamming into the road 14 times a second. That's annoying and can cause your tires to wear out more quickly.