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Tyre riddle

I’m building a 498cc Levis competition-type machine in the style of Butterfields Ltd’s Competition D Special, from an ex-grasstrack racer I bought a few years ago.

It had a bent frame, damaged primary drive crankcase and all its tinware, including the tank, was missing. I’ve since found a suitable Levis tank and I’m building it as a ‘comp’ model because I like the look of the factory ones, while it will also save finding, making or adapting tinware, lights etc.

The rebuilt engine is now running in the straightened frame, the gearbox works and I need to start sorting out wheels. Although it has original Levis type hubs, brake plates and brake shoes, they are currently fitted with 19in rims to both wheels and very old 3.50x19 balloon knobbly type tyres. The Levis specification panel states the Levis Comp D model was shod with: ‘27x3.00 front and 26x3.50 rear’ tyres. These sizes seem nonsense to me, but I know they must be correct, so can you translate them into modern language and tell me, please, what size rims I need.

Pete Markham, email.

The sizes Levis quote for the late-1930s models, including their competition models, are a carryover from earlier beaded edge tyre sizes. These beaded edge tyres were dropped from 1926 season onwards by most makers, but odd models used such until about 1931, and were replaced by the wired on tyres we classic riders are all