The rubber part of the wheel which contacts the ground. The construction can be bias-ply, bias-belted, or radial. The plies are made of rayon, nylon, and polyester. Belting can be fibreglass, steel, or kevlar. The rest of the tyre is hard rubber.

Cross-section through a tyre and wheel rim.

Aspect Ratio

The ratio of section height to section width multiplied by 100.

Bias Belted

Refers to a tyre with the ply cords at an angle, overlaid with reinforcing belts.

Bias Ply

Refers to a tyre with the ply cords at an angle to the centre of the tyre; no belts are used.

Carbon Black

Used as a filler, to provide a uniform colour, and to increase wear resistance.

Contact Patch

Area of a tyre that actually touches the road.


The portion of the tyre between the tread and the bead.


Used as a filler in the tyre rubber to improve life and to reduce rolling resistance.


Narrow slits in the tread blocks that allow the tread block to flex and so increase grip. They also pump water away and so improve wet-weather grip.


Goodyear NASCAR tyres are at an optimum between 90°C and 120°C. If the tyre temperature goes above 135°C they are likely to blister.

Tyre Bead

That portion of the tyre that bears against the rim flange. The bead has a number of turns of steel wire in it to provide great strength.

Tyre Gauge

An instrument for determining the pressure in a tube or tyre.

Historical Notes

  • 1839 Charles Goodyear invented vulcanized rubber later used for tyres.
  • 1845 Robert William Thompson produced the first pneumatic tyre
  • 1888 John Boyd Dunlop produced the first pneumatic tyre for bicycles
  • 1904 Carbon added producing black tyres.
  • 1904 Goodyear and Firestone started producing cord reinforced tyres
  • 1908 Frank Seiberling: grooved tires with improved road traction
  • 1922 Dunlop: steel cord thread in the tyre bead
  • 1943 Continental: patent for tubeless tyres
  • 1946 Michelin introduced the radial tyre
  • 1947 BFGoodrich introduced the tubeless tyre
  • See also: Independent Suspension, Rolling Resistance, Run-Flat Tyre, Silicon Dioxide, Slick Tyre, Slip Angle, Space Saver Tyre, Spare Tyre, Tubeless Tyre, Tyre Bead, Tyre Envelope, Tyre Noise, Tyre Pressure, Tyre Pressure Gauge, Tyre Rolling Circumference, Tyre Rolling Radius, Tyre Speed Rating, Tyre Squeal, Tyre Tread Pattern, Wheel, Wheel Balance.

    Previous PageView links to and from this pageNext Page

    Subjects: Mechanical Engineering