There are three primary sizes we need in American OO: 33” for freight cars, 36” for passenger, and 40-42” for diesel locomotives (depending on the manufacturer and model). Short of custom orders of wheelsets or foreign sources the best options are using wheelsets marketed for On3 or converting HO wheelsets to OO.

From On3 these sizes (marketed by NWSL, for example) have the most promise.

• 20” converts to 31.7”
• 24” converts to 38”
• 26″ converts to 41.1”

From HO these would be the sizes we might make use of:

• 36” converts to 31.5”
• [UPDATE: Several makers produce 38″ wheelsets, these scale out just a bit over 33″ in OO, this size would be ideal for freight trucks in OO with modification if the treads are standard width.]
• 40” converts to 34.9”

In a recent discussion on the OO list a supplier that is new to me was mentioned, Reboxx. On the plus side they offer wheelsets in a variety of axle lengths, the longest length axles are the easiest to convert to use in OO in for example But on the negative side, the Reboxx sets are of a narrow wheel width so I am concerned that they may not operate well on my track. [UPDATE: They don’t work on my track.]

Worth mentioning as well is the NWSL Flea drive is available with On3 components that will work perfectly in OO. This I will have to look into more.