I built a gantry style pipe cart, with these casters. With load centered, on flat concrete, with half of combined rateing, the forks tended to lay over and rub tires. had to straighten forks and reinforce. we`re talking 600 lbs. you would think 450 lbs x 4, you`d have 1400 lb. max rateing. I`d be careful out on rough ground. I priced good american casters at same rateing $650.00 a piece. If work justifies, the purchess of these castors, I`m getting them someday. Cause my cart is designed to haul 12" pipe, and can`t even haul 8".