How does one determine correct axle lengths?

I have some older cars from the likes of AHM, Model Power and Bachmann. When I try to replace the wheels with P2K metal wheels they are very loose and sloppy.

I seem to be having trouble in determining the correct replacement wheels that fit well in these cars. I know that there are companies that mfg different axle length wheel sets but how do exactly do you figure out the correct length?

One in particular is an old Model Power 200 ton diesel crane car. It looks exactly like the Roco and IHC crane. The P2K wheels literally fall out when you pick the car up.

To be really accurate you need a micrometer. There are people who get close enough with calipers. One other thing to watch is the profile of the taper on the ends as there are a few weird ones out there. Some of the wheel guys have recommendations for certain cars.

If you’re serious about model building of any kind, you should have some type of Caliper.
N.W.S.L. and Reboxx have axle size charts.

The Reboxx website does have a chart that may include your trucks, if so, then they will list the axle lengths and suggestion for appropriate replacement wheels.

Rick