Mike, good recommendation. 2x10's work good for leveling side to side. I have two boards I take with me. Cut one long enough to get both tires on and the other a little longer. That way you can stack them on each other for more lift and it's a gradual climb. I even cut the ends beveled so the tires drive up even easier. Have to option to raise the low side either 1.5" or 3". Anymore than that, find more of a level area.