If you are going to put anything of any weight and leave it in place for more that a day, you need to use cast steel or iron wheels.
Even if the rubber or plastic ones that are rated well above the load ( 150 lbs each x 4 with a 400 lb engine) will flat spot from sitting.
Really annoying when it takes a 2 x 4 to get it rolling.
I usually pick ones with a big mounting flange so I can bolt, clamp, weld them on depending on the construction.