Questions, Answers & Tips - 1
QUESTIONS AND ANSWERS
Code 88 Wheels
Q.
Some of my freight cars came with thinner wheels. I’m told
these will only run right on Proto 87 track but they seem to
operate fine on my regular track. Am I missing something?
A.
No, you aren’t missing anything. Chances are you’re using
switches made to a finer standard than much commercial track.
Most commercial sectional and flex track available in the
US is made to NMRA standard S-3.2 but only some available
switches and crossings conform. There is a list of useful links at
the end of this answer.
A Code 88 wheel has a narrower width than the wheels on
most mass-produced model trains. The overall width on one is
.088” wide and the other usually .110” wide. Athearn Genesis
and Atlas introduced narrower wheels on a few ready-to-run
HO cars a couple of years ago to answer modelers’ requests
for more realism. They will run fine on correctly-gauged track.
Other manufacturers have also sold “finer” wheels from time
to time, and there have always been some modelers working
to exact scale.
In addition to their RP-25 lines, Kadee and Intermountain sell
Code 88 wheel sets. NorthWest Shortline catalogs wheels in
widths from .110” to .064”. Reboxx sells Code 88 wheels in a
variety of axle lengths.
As the width of the wheel decreases, so does the tire width
(the part that runs on the head of the rail) and the flange width
(the part that presses against the side of the rail). The recom-
mended wheel flange profile and the taper of the wheel tread
are more-or-less consistent. Some companies use different
radius curves where the flange meets the tread, and some
flanges taper more than others. All of these dimensions inter-
acting determine which wheels work with specific standards.
1
1: Kadee 33”
wheelsets for Code
88 (right) and Code
110 left) show the
difference in wheel
widths. In a Code
88 world, truck
side frames could
be more correctly
spaced to give a
better appearance
under rail cars.
MRH-Feb 2013
