Control arm bushing is the system of parts, the rubber bushing itself, an outer sleeve of metal and an inner sleeve also of metal.  This is a system that prevents metal from contacting with metal. and protects the front end suspension of your vehicle.  This system cushions the suspension of your vehicle, giving you not only a more quiet and comfortable ride, but it also ensures that the handling of your vehicle is in tip top form.  Most vehicle's have just one control arm, but most SUVs and pick-up trucks have two arms, a lower and an upper. When you are inspecting the arms the upper bushings are a bit easier to reach than the lower, but you may find a view of them by looking through the well of each wheel.  The rubber ends will dry and crack as they wear, and this may be a sign that the bushings may need to be replaced in order to have the safest working order of your suspension as well as in order to ease the wear on each Cooper tire.   The alignment of your car will be thrown off, and even if they are off just a touch, these tires will wear out before their time as they will not be able to sit evenly and flatly on the road.  This will affect the ability for you to properly steer your car, as it will be pulled to one side or the other. To install new arm bushings you will need an air chisel, as the arm bushings are tightly secured and will need quiet a bit of force to get them back out.  When you replace the bushings make certain that they are adjusted as is required on your specific make and model.  Here again, if you have an air gone you will have a much easier time making certain that the bushings are secured tightly.  You may need to hammer them out from the inside but make sure that the arms do not get bent.  Once this is complete the final step is to have your vehicle inspected to ensure that it is still in proper alignment.  The control arm bushings are just one element of your vehicle that will affect not only your ability to safely drive your car, but will also affect the wear and tear of your tires, and should be properly and consistently maintained.