The 2 litre models had a specified tyre size of 185/14 and the tyre of choice at the time was the Michelin XAS 185 HR 14, the first production tyre with asymmetrical tread which meant unheard of road-holding capabilities. The first examples were "H" rated so were safe up to 210kph (131mph) and were soon adopted by the racing fraternity. (click pictures below to enlarge).
Below are the official dimensions of the modern replacement of the 185 HR 14 XAS Tyre as specified by Michelin:
In 1967 there was an official announcement that the Fiat Dino would also be shod with Pirelli's Cinturato (meaning "belted") CN36 185 R14 tyre.