My most recent "ramps" are two sections of maple tree logs, cut flat and angled on one end with a chainsaw. I would park an armored car full of gold bars on them and expect them to hold but I was only using them to raise a John Deere lawn tractor so I could sharpen the blades and clean clumped the grass out of my mower deck. They are too heavy to move around much.
I will use them as fuel to make bonfire smores this coming holiday weekend. Redneck engineering with renewable and re-usable resources FTMFW!