I have my backhoe, wood
chipper, wood splitter, landscape rake and generator all on wood dollies. I recommend going with the larger diameter wheels for ease of rolling on concrete. I try to double the weight of the attachment spread over the load bearing weight of the wheels. 1000 lbs. of attachment = four 500 lb. rated wheels or three 600+ lb. wheels depending on the dolly's configuration. The backhoe's dolly had to be carefully designed as to the overall platform heigth for ease of tractor attachment/detachment. Check the wheel's zerk fittings IN THE STORE for proper thread tapping and alignment. Of the nineteen wheels that I purchased from three different stores for the above attachments, two had bad zerks. Iv'e posted these photos before so doing it again for the OP.