How do you keep plastic leveling blocks from slipping?

I had this issue with my plastic ramps on my class c. It only happened on the front tires, never on the back. I was told and shown that placing a 3/4" piece of wood in front of the ramp kept the ramp from sliding. I cut a 2' long piece from a couple of old cedar fence boards and haven't had an issue since. As it was explained to me, it had to do with them not being the drive wheels so that would include TT tires as well.

Don't doubt me, just try it.