If the 16" wheels fit on drums and clear everything, what's the problem? You just need bigger (taller) tires for trucks with high load range, not the wimpy light truck tires. I'm talking 80 or 85% height, not the 70 or 75 usual size. The 17.5 tire will cost more for one or two than all the 16" tires will cost you, then that's IF you can find any.
