Another theory might be that Forghieri tried to counter the deformation of the huge rear tyres under cornering, which in turn reduced the contact patch, thus traction. Having two sets of front tires at the back would give a more rigid solution. At the same time Ferrari tested a De Dion suspension with the same aim.

Carlos Reutemann driving the 312 T6 at Fiorano.

The T6 was tested but never raced. The T6 was never declared illegal as such, but its width was way beyond the permitted dimensions of a Grand Prix car, so it was never officially entered in a Grand Prix.

During a test at Fiorano, Reutemann crashed the only T6, and suffered a rear upright failure on another occasion. The project was then abandoned, and all Ferrari F1 cars have remained on just four tires since then (FIA banned 6-wheel cars shortly after).

A regular rain tire standing beside the twin tires.

Photo Credit : WRI2