I went to Wal Mart looking for a wheel chock for my car. I asked an employee where they were because I couldn't find what I was looking for. When he pointed out this one, I knew why I couldn't find it. I was looking for a black rubber one. I had no idea they made plastic wheel chocks.
I scoffed at the idea and was walking away when I got the idea to test it. I can afford to waste $3.47. So I went back and picked it up. Since they sell these in their automotive section next to the jack stands, I deduced that there were some people that would try to use these on a car. The label says don't use on tires larger than 21 inches. If you have a car with tires 21 inches or less in diameter, you don't have a car. You have a go-kart.
Besides, would you trust your life getting under a car supported by a plastic wheel chock? Me neither.
I put the chock in front of my pickup truck and let it roll down the driveway. Check out the results.