Second that on the wheels from McMaster. I use them on my 1981 (!) Cobra. Even though they are only rated at 150 lbs. each, they have held up well. I do make sure to keep the speed down when traversing a ramp so the impact load is minimized. Since they are steel, they still sound like a grinding crash when in contact with the ground, but the swiveling and rolling action is much better than a fixed, solid skid.