I would be cautious using bicycle tires on a simplex at any speed over 25 mph. These simplex bikes weigh a lot more than a bicycle, and the sidewalls are not very strong. Simplex reproduction tires are very heavy duty in comparison, the only downside to them is the price. Corky Coker is very proud of his products! Wayne has the tires available..
As for wheels, I would look at Worksman rims. These things are built really heavy, and can be bought with drum brakes.
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