I volunteered to help my friend with a brake pad change, and when we looked at the front pads we discovered that one side ( passenger side wheel ) is competely worn, with the wheel very dusty, while another side ( driver side wheel ) has about 30-40% of the pads left. The car is 2002 V6 if it matters. The pins do not seem to be stuck on the worn side, did not check the other side though, so I wonder what the culprit might be. Air in the brake lines? Cant think of anything else... Any ideas?