I've had my Crossfire for about a year, and when I pulled the wheels off for the first time I noticed that a couple of the bolts weren't tight. When I re-mounted the tires I found out why. Two of the bolts - one on each side of the rear axle were stripped. Both of these bolts had reduced depth in the threads.

Any tips on if I can tap these holes to clean up the threads, or go with an oversized bolt, or some other solution?

Appreciate any suggestions.