On the Chaski/Home machinist forum there is a discussion about steel tires on steam locomotives, and it was mentioned that different tinsel strengths were used depending on the usage of the locomotive; mainline passenger or freight, or yard duty. Also mentioned was there were 7 different hardness of the tires.
Anyone have any more info concerning this? Obviously too soft and the tires would wear quickly, too hard and you would loose tractive effort. What is being done now when tires are replaced during a restoration? Anyone have any specs?

Nyle

It has been a little while since I have purchased any railway tires, but when I last purchased tires they were specified in ASTM A-551. A-551 specifies four grades of tires, each with a different hardness. The correct tire grade depends on the service and type of braking. Shopping for tires is a world wide experience and adequate drawings and specifications are required.

An interesting but little-known fact is that when the Wilmington & Western's 0-6-0 steam engine needed new tires, they were able to repurpose surplus new GG1 tires that had been obtained from AMTRAK when they phased out that engine model from service. A little machining was all it took.

I follow both forums and am myself a live steamer. The Chaski guys merely thought it was interesting that real loco tires carried such a variety of strength/hardness. They concluded it really does not matter to a live steamer; the upgrade from cast iron tread to any steel is the big gain. Some rails are mild steel, most are still aluminum anyway.

As for preservation, what locos are worked so hard, or so often, that they really need 100% of the life or performance found by matching the original steel spec.?