that looks good i wouldn't go any lower than that. We got the same basic edging and mine is mounted back further and i still manage to scrape in some places. If you have to go up something like a parking deck ramp or anything take it slow and i mean slow. If i go slow enough i don't scrape in 99% of places. If u want to cover the tires im assuming you didn't use all of the edging you could just cut a small piece out of it and mount it right after the dam.
http://ecomodder.com/forum/attachmen...4&d=1348612461