If the inner shoulder of your tires (the part closest to the suspension) wears out faster than the outer shoulder, it can point to a number of things. The most common is the ball bearing, the part that connects the suspension control gear to the wheel.
Ball joints are strong and can last for years without showing any signs of wear and tear, but age and constant friction can change the camber pattern and cause the tires to wear out. A ball bearing failure can cause your car to have an incorrect camber angle, which tilts the top of the wheel inward and the bottom out, causing serious shoulder damage.
In addition, misaligned ball joints can change the direction of the tire, determining whether the tire is facing in (toe-in) or out (toe-out) from a straight position. Premature wear can also mean faulty bushings, worn coil springs, leaking dampers, or a loose suspension bushing, problems that can cause a change in alignment while driving.
Take your car to a mechanic or garage as soon as you notice that the tires are moving. The problem can be as simple as a wheel alignment, or as complex as a suspension repair. However, make it a habit to check your car’s tires every month to prevent small problems from turning into expensive repairs.