Cars and trucks use wheel bearings to create a smooth rotation between the hub and the wheel and braking assembly. Most models use an "inner" and "outer" wheel bearing design, and while the style of hardware can vary, the basic components can be identified as sealed bearings or opposed open bearings. The average backyard mechanic can replace the front bearings on most vehicles in about an hour.
Lift the vehicle with the floor jack and set the frame rail onto a jack stand. Remove the front wheel by turning the lug nuts counterclockwise, then pulling it from the hub. Set the wheel aside, away from the work area.
Look for a centre cap on most models and pry it loose with a screwdriver along the edge, without removing the brakes. The metal or black plastic cap should come off relatively easily; do not damage the cap or hub using brute force. A spindle nut is inside the opening, with a cottar pin locking it in place. Pull the cottar pin out, then turn the nut counterclockwise. The outer bearing will be accessible and can be pulled out easily.
Access inner wheel bearings by removing the brake assembly and then separating the hub from the axle. The calipers come off by turning their rear mount bolts counterclockwise, then they slide off the rotors. The rotors will either pull off directly or have secondary spindle nuts holding them in place. The hub within has four main mount bolts that will release it when turned counterclockwise. The inner bearing is within this hub housing. During reassembly, grease all bearings completely, and replace the cottar pin with a new unit.
Some models will have a "sealed' bearing system, which incorporates the wheel bearings inside the rotor assembly and hub. The reasons for this design are longevity and compact size in front wheel drive applications, not the cost of replacement. Once the braking assembly is removed, the rotor and hub have four main bolts that release the assembly when turned counterclockwise. Replace this entire unit to replace the wheel bearings. Use high-heat axle grease for added protection.
Use extreme caution when working on a lifted vehicle.