Inside the wheel hubs are either roller or ball bearings that carry
the vehicle's weight. On RWD vehicles with solid axles, the rear
wheel bearings are mounted on the axles. The front wheel bearings
on older rear-wheel drive cars and trucks usually require
"repacking" (regreasing) every two years or 24,000 miles. The wheel
bearings on most newer vehicles are sealed and do not require any
maintenance. A bad wheel bearing will typically make grinding,
whining or squealing noises, and you can often feel the looseness
or roughness if you raise the suspension and rotate the wheel by
hand. Worn wheel bearings should be replaced, because failure may
cause the wheel to come off the vehicle.