Are you using the 500 lb capacity or 1000 lb capacity? I'm using the 500lb model and the front casters just bolt to the frame so they can likely be upsized without too much trouble. I was going to talk to a local shop that does metal work and welding to see what they would charge to replicate/weld same attachment plate to rear of frame so back casters can be upsized to match the front. I made a mod to hinge the handle of the 500lb model about eleven years ago and just replaced that table with a new one a few weeks ago but I've never tried to mount larger casters/wheels and I'm going to check it out.