my valve caps are stuck on my tires!! their metal, i tried everything from wrenching it off and soaking it with liquid wrench and wd-40, and i tried twisting with a rag. i cant get these things off. could it be the heat? its like 51 degrees and its usually been about in the 20's-30's here an i think i put these on when it was cold out...idk but i do know that my tire needs air and i cant the the thing off!!