I have four of the older style standard wheel dollies from HF. They are rated at 1500, but I had to fix one of them that failed when I had the brilliant idea of putting them under a ton and a half. Didn't destroy the caster believe it or not, bent the frame pretty good.
Usually the problem with casters so close together like that is the frame is slightly bent. The bend could affect just one caster or two depending on where the bend is. Put your dolly on a flat table and take a good look. You will find it. HF DOES use really cheapo casters.
