Took out a curb with two tires and wheels. Now in a parking lot, but dark, no glasses, but couldn't find a tool/wrench to take off the round lug nut covers. Best I could see, it looks like an allen, guessing metric, 5, 6, maybe 7 MM. Need to know if so, or if it's a special wrench for when I go back in the morning with a second tire and wheel to change them both. Thanks.