Hudson front pilot bogie wheel diameters

Per Gerbracht's Know Thy Hudsons, yes, the front truck wheels are 36" in diameter.

Just an opinion, but one thing that looks really nice on a hi-rail steam locomotive is a set of scale wheels of proper diameter on the pilot truck. You'd need flat-top rail and to take turnouts are low speed, though.

It does indeed make a huge difference and you do need to run on a T-rail. Here is a Kline Hudson I did years ago.

Drawing found on this site several years ago.

https://ogrforum.com/...j1-hudson-dimensions

The drawing is great, I do like good drawings. 

Ok, now I have something to look into..

I like to use the 2 rail front pilot wheels on mine too....much better looking model....and runs through Atlas switches just fine,.......Pat

A good looking Hudson Pat.

I do like the look of that, very nice... definitely a worthwhile upgrade. 

Slaters (very much “the Old Firm” for this sort of thing in the U.K.) do a 19mm Steel disc wheel in O Gauge, that looks like the first thing to try. 

I’ve now sourced a spare pilot so I’ll pay a quick visit to Slaters website and convert the spare pilot when it appears, and see how it develops.