First I apologize for the errors and incorrect questions I posted above , ie asking about a wheel when I meant tire or posting erroneous data. In removing the tire-less insulator from the axle I broke the insulator - see photo 2 - never had that happen before. I decided to pursue the following:
Using an old freight car wheel set with insulators on both wheels(see photo 1) remove one wheel and insulator, chuck axle in a Dremel(or equiv) and using a micro-file, on remaining wheel turn tread dia. down to 5 mm and flange dia. to 6 mm.
If the turned down wheel doesn't have a shoulder on the insulator as shown by red arrow in photo2(original pilot axle) or photo3(Minitrix freight car wheel set) use an insulating washer( similar to one furnished with M/T trucks as a spacer) to keep wheel from shorting out to pilot frame.
Photo4 shows completed wheel(rear wheel on pilot). Locomotive runs fine in opposite direction to throttle and tries to pole vault every turnout and crossover it encounters.
I think I'll set it out front of my round house and work on +- 2ft lateral movement on my schnabel car - how many n-scale schnabels have that?