Take those 'plastic' wheel chocks and toss them in the garbage.
Then do yourself a favor and buy some Race Ramps 'RUBBER' wheel chocks. These suckers are SUPER durable, very solid high quality product. Unlike plastic, they will NOT slide away no matter how smooth the surface is. You can drive over them, but will NOT crash even under 15,000lb trailer weight.
Before I bought them, I struggled with plastic and wooden chocks. Until I gave them a try. I will never look back. Unlike, plastic or wooden chocks, you don't even have to 'kick' them inside the tire in order to hold in place. You simply place them against the tire= done.
I use them to chock my 5'er. Even while working on my cars.
Amazon has them for around $60 for 4 of them. See link below;