1999 FLHR Tyre Valve

[Limey_Dave]

The parts book doesn't list any tubes,just a rubber valve and a metal valve.
Before getting new tyres I phoned Silverstone HD for price of tubes.He asked rubber or metal valve,I said metal,he said £25,I said no thanks.
It got a pair of Conti tubes.
Last Saturday at Stafford there was a Conti stand so thought I'd get a spare.
Told him bike details,he asked centre or side valve,told him and he asked rubber or metal valve?
What is it with these rubber valves,when I've thought to look I've never seen a TC with them and only recall seeing them on Flatheads.
Rim holes are a "snug" 11/32" (0.340") and the valve is 0.300" so they're the right ones for my rims I would think.
What size are the holes for rubber valves?