Most competition tyres are produced in slick moulds for convenience, cost and versatility. If patterned tyres are required for wet-weather, off-road or historic applications they can be hand-grooved or cut to order. This picture is of Norm Faulkiner in his 1967 Elfin Mono with his mechanic Jim Hardman. The tyres are Avon slicks hand-cut to historic pattern. Stuckey Tyre Service specializes in this service and can cut any tyre to virtually any pattern.
The Avon Historic race tyres listed at http://www.stuckey.com.au/Tyres/Motorsport-Tyres/ProdID/89/CatID/13 are all hand cut as demonstrated by the embeded clips.