RP-25 Wheels

[Anonymous]

"OK" so I've been asleep under a haystack, whats the skinny on RP-25 wheels?
I mean the whole skinny cuz I don't know a thing about them. Thanks to all who
respond.

[willy6]

I have used KADEE,PK2 and IM, in my opinion Kadee were the best for me. However, you will hear other comments from the IM and PK2 people.[swg]

[IRONROOSTER]

This site http://www.nmra.org/standards/rp25.html has the specs. The idea is that this represents an optimum balance between appearance and operation. Those who are into scaling the protoype down directly prefer a closer to scale wheel but this works well for most people.
Enjoy
Paul

[BR60103]

RP-25 (Recommended Practice #25) came out a long time ago - the 60s? - and was an improvement over the NMRA standard wheel profile. The main features were the reduction of flange depth from .035" to .025" (in HO) and a rounded flange. The basis was that a round flange would slide off rail joints, particularly misaligned ones, while thin, sharp, "pizza cutter" flanges would catch on them and ride up over the rail.
It was never made a standard, and a lot of companies still make wheels that are worse than standard.

[dknelson]

There was another key to the RP25 and that was that the wheel tread is not parallel to the rail from edge to flange and that there is a curve leading into the flange. Before that some wheels where perfectly flat, like a dowel with a flange, and the flange was rounded rather than knife edged. The theory is that the wheel is less likely to pick points, will go around curves better.
I am not explaining this very well. There was an MR article from the early 1960s that did a great job of explaining all of this
While not all wheels today are RP25 there are few if any that follow the design that was common back in the early 1950s.
Dave Nelson