BERLIN: Winter tyres, summer tyres, coarse-tread tyres for real off-roaders and no-tread slicks for racing cars — alright, you know your way around car tyres.
But have you ever heard of radial tyres?
Until the end of the 1940s, tyres for cars and trucks were produced with a diagonal pattern: Several crossing layers of rubberised cotton threads formed the framework for a corresponding tread.
"This was easy to manufacture, relatively robust and repairable, but only of limited mileage and not very suitable for the increasing demands on the driving dynamics of modern vehicles," explains tyre expert Christian Koch from inspection agency Dekra.
A large French tyre maker was then commissioned by a vehicle manufacturer to develop a tyre that would take account of modern drive concepts — for example, front-wheel drive and the associated heavy tyre wear on the front axle.
This was the birth of the radial tyre.
With the new tyre type, the threads no longer ran diagonally, but at a right angle to the rolling direction.
"The reduced stability was compensated by the fact that two so-called belt plies consisting of steel cords ran around the tyre circumference," explains Koch. Put simply, these steel cords were a special type of wire rope running along the tyre.
The resulting radial belted tyre still represents the basic design principle of modern tyres today and the superiority of this design is still evident more than 70 years after its invention.
"The radial belted tyre is capable of carrying heavy loads — up to several tonnes in heavy commercial vehicles — as well as withstanding high speeds of over 400kph on corresponding vehicles," says Koch.
The only problem is: Radial tyres can only live up to their promise when they are inflated with enough pressure.
Several tyre manufacturers are currently trying to counteract this with changes that deliver the same technical advantages but without the need for specific inflation pressure.
