Split spoke wagon wheel.
Railway Clearing House dimensions for 8 and 10 ton wagons.

3′ 1″ diam. (3′ 1½″ with thicker tyres), 8 split spokes, rectangular inner rim, 2½″ apparent tread.
Hub 13″ diam, 1″ out from the tyre.

Source: L. Tavender, Coal Trade Wagons page 9.

Casting: 41.6 mm tread dia., 36.4 mm i/d., hub 1.1 mm out from the tyre.
5″ tyre width at this scale = 5.6 mm.

Gauge 3 loco and wagon set prices . Casting prices and stock

Bare weight c. 80 gr. each, 320 gr./set of four.

Suitable for the Gauge 3 Society 2010 minimum tyre width of 6.8 mm, or the earlier standard of 8.0 mm.