Hi Peter
Many ACOC members in the UK & Europe run their Ace's and Aceca's on 165HR16 (550x16) AVON TURBOSTEELS.
I've done some 16,500/17,000 miles on mine (BEX333) including Various Sprints, Races and Hillclimbs ....... still plenty of tread.
Front tyres scrubbed on outer edges, but swapped to the rear.
Road holding and comfort far superior to sets of Dunlop Racing Tyres I used for years before suitable Road / Track tyres were available.
Avon also manufacture 15inch version in softer compound, ideal for racing, However not sure if the softer compound would last long on the Road.
Have you modified your rear wheel arches to accomodate 185 x 16s, or have you altered the rear spring to give negative camber? Most 185 cross section tyres foul bodywork or burn off paint, especially when two up or really motoring and enjoying open sweeping roads.
Cheers
Keith