Small stones and dust particles can chip away at the paint over time.
Alloy wheels often pick up damage and cracks around the outer rim. This is usually caused by a car hitting a speed bump too hard or hitting a curb.
If there is a particularly heavy impact, the alloy wheel could possibly even split. This would mean the part would need replacing and a spare wheel fitted, until you can have a new wheel put on your car.
Cost of Repair:
If the damage is only cosmetic, the repair will be quite simple. A service called powder coating will restore the appearance of the wheel. First, it is blasted by hand/given a chemical strip to remove the top layer of paint. Then, the wheel is filed to deal with any potential damage to the edges of the rim. The wheel is then heated to remove the air from the alloy, and the first layer of powder coat finish is applied. The wet-in-wet procedure can then be applied before the wheel is heated again. The cost will depend on the extent of the damage as well as the size of the wheel, so it is a good idea to get in touch with local garages for quotes.
If you have one or two cracks, these can be welded shut by a mechanic, so you shouldn’t need a brand new alloy. The cost to weld a crack will vary depending on the size of the crack, so you would need to get in touch with local garages for quotes.
Three or more cracks would mean you would have to get a new alloy, as the structural integrity would be beyond repair. If several cracks were welded, the wheel would not be safe to drive on. The cost of a new wheel would depend on the car, so a bigger wheel would cost more.