In general, dented alloy rims are almost always a result of inadequate tire pressure, and are not a warranty issue.

Some riders prefer to run low tire pressure to achieve added traction, with the understanding that their rim may contact the ground, potentially causing dents. These riders need to consider rims as consumable items which need regular replacing. Riders who want to avoid dents entirely need to run higher pressure than those willing to sacrifice possible denting in exchange for added traction. 

Alternatively, running a tire with a heavier duty casing, a tire insert, or a rim designed for heavier impacts such as our Grappler or LG1 DH rims will improve dent resistance. 

Here is some info on tire pressures we recommend to avoid denting: What tire pressure should I run?