Car tyres are made fat so as to provide grip…but that also entails a big downside: rolling resistance.
Today’s invention enables road-going vehicles to minimise their rolling resistance and thus save significantly on fuel.
Each of the wheels would have a tyre fitted with a super-resilient inner edge (this ring might even be replaceable, separately from the main tyre itself).
When travelling at a uniform speed, the wheel would rotate inwards at the top slightly so that only the inner edge was in contact with the road: a) (and possibly also disconnecting the drive to that wheel).
When any acceleration, deceleration or cornering was required, the wheel would take up a vertical position, providing the required grip: b).