[Big Dave]

I used 3/8" ripstop conveyor belt for my air dam.

The stuff is a bear to fabricate and not at all cheap, but it is flat indestructible. I've had it on my truck for over five years and and it is in good shape. A little rubber conditioner and it looks like new.

After much experimentation I found that the right height for the air dam is about 7" above grade in front of the wheels and 9" above grade in the center. this height keeps it out of parking curbs.

I tried my air dam as low as 3" above grade but at that height it dragged the ground every time I hit the brakes. No major damage (just ground the botto a little, but it annoyed the hell out of me.

I'd recommend the stuff.