A 3.00-20-50 is probably a modern low-profile tyre, and not very suitable. A 50% aspect ratio tyre is flattish and low. The original tyres were from 80% to 100% aspect ratio. I can recommend Coker tyres – I have used them for years on other historic vehicles. Although you may have to import them directly from the U.S., they can compete very favourably pricewise.
Cheers!
Carl
