About the wheels of a trolley
If you are not pushing the lighter goods, so the wheel diameter is about 120mm, with a foamed material can tire (of course, can also use PU or rubber materials, rubber and PU material is not more expensive), you can not install the bearing axis axis, but heart and butter, then push up more effort.
If you are pushing less heavy goods, then the wheel diameter is about 200mm, the tire is rubber or PU material, the axle is best to have bearings, so pushing up more labor-saving.
