A major technical change for 1991 was the introduction by Avon of radial-ply tyres. Compared to the previous crossply tyres, these could be more consistently manufactured, and made the cars more consistent aerodynamically, but gave the drivers less control at high slip angles.[1]
Lola's T91/50 chassis was an evolution of the previous year's championship-winning T90/50, and retained a very short wheelbase of 263.0 cm (103.5 in). By comparison, the Reynard 91D had a wheelbase of 277.5 cm (109.3 in).[2] The short wheelbase of the Lola was blamed for its inability to perform on the new tyres, and the Forti Corse team switched to Reynards after three rounds. The Eddie Jordan Racing team attempted to lengthen its Lolas by adding a spacer in between the engine and gearbox, but eventually it too purchased a Reynard for Damon Hill.
The Ralt name, last seen in F3000 in 1988, returned after being split off from the March Group.[3]
Gounon won on the road at Enna, but he was controversially adjudged to have jumped the start. The race win was given to Emanuele Naspetti, who was making his first start in a Reynard after his Forti team had switched from Lolas. Naspetti then won the following three races at Hockenheim, Brands Hatch and Spa-Francorchamps. His success was blamed in part on the exotic fuel blend provided by Agip, which would be banned the following year.
Fittipaldi's Pacific teammate Antonio Tamburini won on the Bugatti Circuit at Le Mans. In the finale at Nogaro, Fittipaldi beat title rival Zanardi for the race win and the championship.
For every race points were awarded: 9 points to the winner, 6 for runner-up, 4 for third place, 3 for fourth place, 2 for fifth place and 1 for sixth place. No additional points were awarded.[7]
