i Have a pair and used them for my tandem axle boat trailer. They worked great.
I have a collection of 2x6 and 4x4 blocks with 45* angle end cuts for the same reason....very easy to kick out. Used scrap wood so they were practically free. Also easy to store as they stack on each other and take up little space.Most of the time, I find short 2x4s work just fine, unless at a extreme angle. Easy to kick under the tire, and back out.