[quote name='34C' date='22 Aug 2008, 10:25' post='60068']
"Code 75 looks a lot better thanks to the finer rail section, which is a good approximation to scale for 4mm. You will need to use RP25 or equivalent standard wheels - most OO from the last thirty years will run without problems, except Lima which had very deep flanges."
If you have any old Hornby or Mainline/Bachmann rolling stock that you wish to run on code 75 track, it is worth checking the back to back gauge on the flanges. If they are less than 14.2mm back to back, you are likely to suffer derailments at the point crossings (frogs).
I have replaced all my suspect wheels and all plastic wheels on old stock with modern metal wheels. The cheap wheel sets produced by both Hornby and Bachmann for this purpose are effective. Unfortunately they are not suitable for old Lima stock which has a different axle length and frequently ran with undersized continental wheels. At a pinch, you can turn down Lima's deep flanged metal wheels in a lathe or a drill chuck. They can then be regauged to 14.2-14.5 mm back to back which is acceptable for code 75.