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′ 6″ diam., 20 oval spokes, vee inner rim, 4″ apparent tread.
Hub 20½″ face dia., central disc 25″ dia., raised by ¾″. Central disc is 2¾″ above the tyre. Pin at 14″.
Source: No. 46203, Princess Margaret Rose measured direct in March 1997 at Swanwick.
Casting: 45.5 mm tread dia., 40.4 i/d., hub centre 1.6 out from the tyre, pin at 8.17 mm.
Casting prices and stock . LMS loco sets, price list
Scan of a casting in a set for a LMS 4-6-2 Princess class
27 Mar 2013