Correct tyre pressure and good tyre condition are two of the main contributors to road safety during wet weather. This is the word from Public Relations Manager, Mandy Lovell, who was commenting on the recent heavy rains in some of South Africa’s summer rainfall areas.
“The kind of heavy downpours experienced during South African thunderstorms place extreme demands on a tyre,” she said. “The contact patch of each tyre, which is about the size of the palm of one’s hand, must be able to clear away water effectively to remain in contact with the surface of the road.”
The tread pattern on a tyre enables water to be cleared away. As the tyre moves along the surface, standing water is channelled into the grooves of the tread and expelled, while remaining surface moisture is mopped up by smaller slits in the tread blocks known as sipes.
But if a tyre encounters more water than it is capable of dispersing, it loses contact with the road surface and is unable to transmit braking, steering or acceleration forces. This condition is known as aquaplaning or hydroplaning, and can result in complete loss of control of the vehicle.
A brand-new tyre with the full tread depth is best able to resist aquaplaning. However, as a tyre wears and the tread grooves become shallower, aquaplaning resistance declines. A tyre worn to the legal limit may not be able to disperse the amount of water found on roads during a typical rainstorm – this could result in the vehicle going into an unrecoverable skid.
“Reducing speed is also important in wet weather,” said Lovell. “Even with brand new tyres, if a motorist is driving too fast for the amount of water on the road, the tyres may reach the limits of their capability to disperse water and begin to aquaplane.”
Aquaplaning is not the only danger on wet roads, with traction also being reduced. A brief rain shower which wets the road surface without leaving standing water on the road can increase braking distances by a third to a half, or more,” she commented. “Roads which are heavily contaminated with oil or diesel may be even more slippery in wet weather,” she added.
Motorists are advised to ensure that their tyres have adequate tread depth for water dispersion during rainy weather, and that their tyre pressures are correctly set to give the optimum traction in wet or dry spells. Drivers need extra time and distance to maintain safety in wet weather. Properly-inflated tyres, in good condition, will help ensure there’s control when a driver needs it.