Intermountain Railway 40053 - HO 28 Inch Semi-Scale Insulated Brass Wheelsets - (12/pkg)

HO 28 Inch Semi-Scale Insulated Brass Wheelsets - (12/pkg) Nickel Silver Plated Brass Insulated Wheelsets These wheels follow NMRA RP-25 Standards. One wheel is insulated from the all-metal axle. The entire wheelset is non-magnetic. The axle length is 1.006in (+- .004in) 28in wheels are used on modern Tri-Level Autoracks, some Bi-Level Autoracks, and some older intermodal cars such as Impack spine cars, front runners & four runners - check your prototype. 33in wheels are used on 50 & 70 ton capacity cars (CAPY approximately 150,000 LBS or less). 36in wheels are used on 100 ton capacity cars (CAPY approximately 200,000 LBS), and on all passenger cars no matter the era. 38in wheels are used on 150 ton capacity cars, primarily the center connection trucks on modern intermodal cars with 33in wheels at the coupler ends. (Cabooses can use either 33in or 36in wheels depending on the prototype.) The CAPY information is typically printed on model freight cars and can be used as a guide. Some cars have the wheel size printed on the sides or ends of the car in the data. If you are ever unsure of which size to use, you can simply replace the wheels currently on the car with the same size. Wheel diameter can be measured with a caliper: 28in wheels measure (28/87.1=.321in) in HO scale. 33in wheels measure (33/87.1=.378in) in HO scale. 36in wheels measure (36/87.1=.413in) in HO scale. 38in wheels measure (38/87.1=.436in) in HO scale. (87.1 = HO scale to prototype ratio. HO scale is 87.1 times smaller than the prototype).