I have an MTH Premier Alco DL-109 6-axle diesel that has flangeless tapered wheels on the inner axles. The distance between the outer faces of the wheels is 1-19/32 inches. The distance between the inner faces of the wheels is 1-3/32 inches. The wheel tread (outer face to inner face) is 1/4 inch. The inner tapered portion is 1/32 inch wide and the outer "cylindrical" portion is 3/32 inch wide. The diameter of the "cylindrical" outer part of the wheel is 7/8 inch (42 inches full scale). The width of the metal frame in which the axle is mounted is 31/32 inch. The taper angle appears to be 45 degrees.
MELGAR