The Coupe and Convertible models were fitted with a 650-16 crossply tyre from 1957 to 1961, and a 670-16 from 1962 to the end of production. Suitable radial replacements for these sizes would be a 670R16 or 185R16, in suitable speed ratings.
The 3500GT marked the point Maserati managed to exploit its racing success and fame, and make a series production GT roadcar. Previous efforts had been more like bespoke racers for the road, and made in very small numbers. The 3500GT wasn't exactly mass-produced, but it was a series production car, and it's mechanicals and styling were progressively developed during production. A successful model that led to great things!