A couple of comments since I went through this. You can level on one tire but you put a lot of weight on the block. If you are on softer ground or sand the block can get pushed into the ground. The stepped blocks were all sold out up here so I bought a set of Rhino Ramps that were rated for 12,000 LBs. BIg mistake. They probably be alright on concrete but on soft ground they buckled and collapsed. I made some hardwood ramps from 4x6 which work well and at the end of the season I was able to find the proper stepped blocks but make sure that I have one under each tire. I've picked up some 1/2" aluminum plate that I'm going to cut into panels to put under the ramps. They may be a bit slippery so I'll try contact gluing some old inner tube to them.