If this is diesel or gas powered, its got to be 7.00x12s on the front and 6.00x9s on the rear. 2.50Ton diesel standard fitment.

no dataplate? all this would be on that

otherwise if you want definate accurate information you can call the hyster dealer in your area and have them contact nacco and pull the line card on this truck to find out exactly what it is.
There are a couple of versions of this truck in the manual and the capacity ranges vary somewhat depending on certain options that are on the truck.
They range from 3470kg to 4100kg... a fairly large difference.

call hyster to find out for sure