Good bearings cut friction so the car rolls freer and the motor works less. Replacing worn or low-grade bearings improves run time, speed and smoothness.

Rubber-sealed bearings keep out dirt and last longer in the wet and dust. Metal-shielded spin a little freer, which racers prefer where conditions are clean.

Bearings are sized by inner, outer and width in mm. Check your car’s manual or measure the old ones, and a full set covers the whole car.

Clean out grit and re-oil them when they feel rough. Replace any that stay notchy, since a dragging bearing costs speed and run time.