Winter tyres: advice for safe driving - Why two winter tyres are not enough?
Center

Why two winter tyres are not enough?

Winter tyres Published the 22/03/2013 by Ellen

To cut costs, it may be tempting to fit winter tyres on the drive axle only. Yet, this common practice is not without its dangers. Rezulteo has checked this out by participating in tests organised by Michelin on the Val-d-Isere track in Savoie (France).

Two ou four winter tyres? The Michelin Test Two ou four winter tyres? The Michelin Test - Copyright © : Rezulteo

 

Driving with winter tyres on the front and summer tyres on the rear is a relatively common solution. However, motorists do not always assess how dangerous this solution is.

Indeed, with this configuration, the vehicle’s road handling performance deteriorates considerably.

What happens when tyres with different qualities of rubber are fitted? When temperatures drop below 7°C, the performance reversal threshold between two types of tyres, the winter tyre will come into its own thanks to the high silica content; unlike the summer tyre whose rubber will harden with the cold.

The result? A difference in grip between the front and rear tyres.

In practice, this results in a tendency to understeer (the front of the car slides) or oversteer (the rear of the car slides), depending on which axle the summer tyres have been fitted.

To demonstrate this, take a look at the video filmed during tests organised by Michelin on the Val-d’Isere track.

Driving test on snow

 

  • Vehicles used:Renault Megane 3 and Peugeot 3008.  
  • Tyres fitted:Michelin Alpin 4 (alpine tyre) on the front, and the Michelin Primacy 3 (summer tyre) on the rear.
  • Dimensions: 195 65 R15 for the Megane 3, 205 55 R16 for the 3008.
  • Surface: packed snow.
  • Test conditions: Slalom test at constant speed with normal, non-sporty driving.

The result: In these conditions, the car demonstrates good traction capabilities. But, the slightest touch on the brakes or the slightest steering correction, throws the rear into a violent slide, unpredictable and almost impossible to curb without a good dose of control and anticipation.

In the video, you can see that opposite lock must be applied early, even before the vehicle has started to slide, to reduce the risk of the car spinning. This behaviour is more obvious on snow, but it can also occur on wet or dry roads. 

Our advice: Always fit four identical, homogeneous tyres on both axles. If tyres have different degrees of wear, fit the most worn tyres at the front: A lack of grip at the front is easier to control.