Tire uniformity

Tire uniformity ( engl: tire uniformity ) denotes certain dynamic mechanical properties of pneumatic tires.

Through the tire and automotive industry precisely defined measurement standards and test conditions for tires have been established. These measurement standards include the parameters radial forces, lateral forces, conicity, radial runout, Lateralunrundheit, Seitenwandauswölbung, Plysteer and sinking depth.

Worldwide leading tire manufacturers and car producers by Gleichförmigkeitsmessungen to identify tires with poor performance characteristics and to sort out. Here, between OE tires ( original equipment ) and replacement tires are distinguished. OE - quality prevails when the tires comply with all vendor -related targets after vulcanization. These tires may need refinished again, be ground for example, to comply with the specified by the vehicle manufacturer specifications. The ratio between the tires that comply with the vehicle manufacturer's specification without a correction must be made and tires, where a correction is needed, is referred to in tire production as so-called Virgin Yield.

Lateral forces

Lateral forces are triggered by that one side of the tire a greater material thickness (thickness ) than the other side. This leads to vibration and shaking at the braking and acceleration forces.

Radial forces

Under centrifugal forces, the lateral forces of the change is to be understood when the tire runs under load. As a guide in the Americas 1000 lb. on a perfectly flat road. A variation of 995 pounds to 1003 pounds would be referred to as an 8 -pound radial force. Thus, the radial force, the difference between the maximum value and the minimum value dar.

Taper

The taper is a dimensionless parameter, which is formed under non-uniform conditions. These conditions are best described as a conical shape of the tire formed under running conditions by lateral forces. This tendency results in an influence on the control behavior of the vehicle. To measure the taper, lateral forces must be measured in both clockwise and counter- clockwise. The taper is specified as half the difference between two measured values ​​, and we must not forget that both values ​​have opposite signs. Normally on the left and on the right side of the vehicle tires with the same conicity mounted to compensate for their Konizitätseffekt each other. This allows for a smoother ride. Higher taper also results in a shortened service life of tires.

Structure side force

In the structure of side force is a lateral force, which is exerted by the disposition of the individual fabric layers in the tire, depending on the respective composition. These forces are determined by the arrangement of the so-called belt, a specially calendered rubber or steel wire layer, in particular by the angle of the belt each other. The structure of the lateral force is different depending on the conicity of the rolling direction of the tire. The two forces superimpose each other.

The structure of the lateral force is used to offset the force exerted by the inclined road surface to the road outside forces. For instance, a tire in the UK an opposing lateral force structure than vehicle tires in continental Europe.

Correction of the tire uniformity

The variation of the radial and lateral forces can be corrected or reduced by a so-called tire uniformity Materialabschleifung at certain points of the tire. This abrasions result in different locations of the tread to different results. Reduce abrasions in the center of the tread or eliminate the variation of the radial forces. Abrasions are made ​​to the shoulders of the tire, this reduces the size of the road contacting surface, also called footprint and leads to a reduction of the Konizitätwertes.

Swell

• Tyres