blocks for leveling under jacks and tires

I'll chime in to say that I've successfully used the yellow lego blocks as landing pads for the jacks, as well as to drive up on when there wasn't enough jack to get on level without lifting the rear wheels off the ground. I've never had a problem with them breaking, although they will warp slightly, and they are really bad about smashing into the ground if it's soft, (it can take quite the effort to dig them out when it's time to go). I left imprints on asphalt once, last year in September in Virginia Beach, in average 95 degree days for a week. But, my square block imprints were among the many round jack prints on the blacktop....and mine had pretty patterns... LOL! The campground should have poured concrete instead.......they readily admit that........