I didn't know the rollers had tires. Mine are bare steel. I'm trying to come up with a product to make some. Looks like the rubber needs to be 1/4 inch thick. Without the tires, the belt has to ramp up to the table from the drive roller, then ramp down to the top roller. There's a ramp worn into the cast iron on both ends of the table. I think this is creating a lot of drag, and making the motor work harder. 1 hp isn't as powerful as I thought.I have an American made sears belt sander still works great
I love my good old 1950s tools
I'm thinking that fitting two layers of 6" base, adhered with contact cement, might be enough thickness for the rollers.
Multiple strips of automotive serpentine belt might work too, but that might be a bit on the spendy side.