Wheel Alignment (tracking) vs Wheel Balancing

low levels of imbalance will not show up as tyre wear, but may show as steering or vehicle shake, at high levels it can cause uneven patchy wear on the tyre.

Minor Tracking misalignment won't usually make much difference to handling but will wear the tyres unevenly, usually the outside or inside will wear more. At high levels of misalignment the handling becomes really weird and even dangerous, tyres may even squeal in a straight line, sharp turns may cause you to go straight on as one wheel can turn far enough to lock up or touch bodywork.

Wheel balance would never be noticed on MPG figures, but tracking might.

Mrcheerful