This example shows a tyre width of 3.5 mm for Gauge 0 Fine.
For Scale7 remove more metal from the back of the wheel to give a tyre thickness of 3.2 mm instead of 3.5 mm.
6′ 9″ diam., 21 oval spokes, vee inner rim, 4″ apparent tread, 5½″ tyre width.
Hub 20½″ face dia, 2″ out from the tyre, pin between at 14″.
Source: Duchess of Sutherland measured direct at Bressingham, Oct. 1994.
Casting: 47.3 mm tread dia., 42.3 mm i/d, hub 1.1 mm out from the tyre, pin at 8.2 mm.
Tyre widths for exact scale models at 7 mm/ft, 5½″= 3.21 mm.
Casting prices and stock . LMS loco sets, price list
Scan of a casting in sets for a LMS 4-6-2 Duchess class
27 Mar 2013