Face a roundabout it can be an operation that puts a strain on the grip of the tires on the asphalt. When you arrive near a roundabout, in fact, it often happens that the tires of the car tend to give a slight sensation of instability and lateral sliding.
The phenomenon, although quite common, can alarm even the most experienced motorists. Accidents near roundabouts are relatively frequent and tires, when facing a roundabout, tend to be less adherent to the asphalt, creating a sort of “ice effect“.
This depends on the coefficient of friction of the asphalt of roundabouts which, due to intense traffic, drastically decreases over time, even in a short period, passing from the standard of 0.6 to even 0.2. Driving in a roundabout, therefore, can seem like driving on an icy road, as the coefficient of friction of the ice is just under 0.1.
A decline of grip in the roundabouts, therefore, it is quite normal: at the same time, we must always try to approach them with the utmost caution, in order not to run into unpleasant surprises that safety of the driver and all occupants of a car, as well as cars outside.
The grip of the tires on the road is one of the characteristics most known to motorists, often even more than rolling coefficient which affects i fuel consumption of a car. But what are the reasons that lead a tire to have different grip depending on the road surface?
The grip that comes into play in acceleration, braking and lateral grip of a car, the latter very important in the case of roundabouts, is the result of the work of the tire lugs.
During the journey, when the tires roll on the asphalt, the tire blocks cling to the irregularities of the road surface and this happens regardless of the state of tire wear. The rubber molecules and the asphalt molecules, in contact with each other, generate gods intermolecular bonds which are progressively reduced when the asphalt is wet or raining.
In general 50% of the adhesion depends on the mix and its composition, while the remaining 50% can vary according to the type and surface of the road, weather conditions and tread wear.
– .
