[larryweikartsr]

I made that type of wood lift out of 2X12's with each one being about 4" forward of the last to raise the coach and the only time it split was when I drove on it too far off center and then it only split the top board. Used this at many race tracks in the country to help level the coach on big slopes and have been under it many times. I did not use treated lumber but did make sure I bought top grade boards. If you make the bottom board 12" longer than the next, so that the tire has room to get on the first board without hitting the next, you'll eliminate most sliding regardless of the surface. The rear boards need to be quite long if you have a tag.