Green tyres, fuel savings, CO2 emission - Smaller tyres for better energy efficiency

Smaller tyres for better energy efficiency

Environment Published the 09/06/2011

For the 10th edition of its challenge (in Brazil in 2010), Michelin widely promoted the positive effect of a reduced-diameter tyre on a vehicle's energy efficiency with the Citroën C2 fitted with 10-inch tyres (14-inch for the original version). This project is still topical and one avenue of Michelin's research and development, so naturally the technology was highlighted once again at the 2011 Challenge Bibendum.

Citroën C2 with Michelin tyres Copyright © : All Rights Reserved

This technical solution which is a throw back to the Austin Mini, is mainly designed for city cars with considerable advantages such as reducing unsuspended weights. Compared to a set of 4 rims with 14-inch tyres or 10-inch tyres, 15 kilos can be gained and almost 40 kilos with the inertia of movement.

Michelin also presented a solution called "Tall and narrow", designed for saloons, with the width of the tyre as the avenue of development. The aim here is to significantly reduce the width of the tread while conserving a large diameter. All this is to reduce rolling resistance and road noise, while improving the CX (drag coefficient).

A new Tail Narrow tyre from MichelinCopyright © : All Rights Reserved

The real technical challenge, despite the size constraints, is to maintain a high level of safety, making up for size with the rubber compound and at the same time reducing the quantity of raw material used to make the tyre.

These solutions are currently being studied in collaboration with car manufacturers, and are the potential precursor to the cars of tomorrow. 

The 10-inch tyre to the test

Michelin's objective in making the C2 10-inch was clear: demonstrate that it is possible to make a smaller tyre with less raw material, while maintaining a level of safety and comfort similar to the levels of a conventionally-sized tyre.

Citroen C2 with Michelin tyreCopyright © : All Rights Reserved

The test starts with a Citroën C2 in its original configuration, i.e. with 14-inch tyres. We took a typical route at a town pace with various segments, including bumpy portions. The first passage was used as a basis for comparison.

The second stage of the test was at the wheel of the same Citroën C2 but fitted with the 10-inch tyres. The first observation is... that absolutely nothing happened! At the wheel, there is no difference driving the C2 with 10-inch tyres from its counterpart with 14-inch tyres. In all respects, the car offers the same sensations, be it in terms of feeling, comfort or driving precision.