There are different types of wheel bearings. Don't mess with four wheel drive trucks. Passenger cars, however, come with sealed and resalable bearings. The sealable bearings are the ones you can work on. They are generally found in the non-drive wheels. If you have a front wheel drive car, they would be on the back two tires.The vast majority of resalable wheel bearings actually consist of two bearings, not one. There is an inner bearing and an outer version. The bearings come in different designs, but they tend to be grooved and concave. When they start to have issues, they tend to show as much through a simple sign - the wheels will wobble in and out a bit. It can be difficult to tell when driving the car unless there is a major problem. For us lazy men, however, there is another way to tell.
The lazy man's method to checking wheel bearings does require a bit of work. You'll need to jack up the car so the tire you are looking at is up off the ground. Make sure the car is secure. Now grab each side of the car and pull it towards you and push it way. There should be some minor give, but nothing more than that. If the wheel moves more than half an inch, you have a bearing issue and there goes the rest of the day. If the wheel is stable, its time to kick back!
Wheel bearings are some of the most overlooked aspects of a car. When they start to go bad or the grease around them gets "funky", your car's ride can be affected. Keep an eye on them and you can avoid problems.