Cracks are common in alloy wheels. Typically they are accompanied by a bend. They can cause the tire to lose air and are a nuisance. 

The most common cracks are on the inside tire sealing surface and are usually repairable.

Cracks on the face of the wheel are less common but can be repaired in many cases.

If you're unsure about whether your wheel is repairable, This email address is being protected from spambots. You need JavaScript enabled to view it. us a picture or stop by.

Examples of repairable cracks:

Examples of badly cracked wheels that are usually not repairable: