by "load wheels" i am assuming you mean the type found on narrow aisle reach machines... or "long johns" i.e. ride-along pallet trucks with double length forks. superior tire and rubber in warren PA offers a cushothane EZ wheel with 85A hardness and high tear strength for rough floors. if you go with the XL you will have higher load capacity but you will rattle the fillings out of your teeth. i think the real answer here if the wheel costs are getting out of hand is to correct the floor conditions.
a bit more information would be helpful i.e. what kind of machine exactly, decribe the specific trouble areas of the floor but again, if youve asked this question youve probably tried several different wheels and still arent getting the life you want so i would focus on improving the floor or modifying the truck to suit the floor.