Tyre Constructions

There are two different types of tyres manufactured today: the radial ply and the diagonal ply. These tyres are named and identified by the way they are constructed, as indicated by the illustration.

Radial Ply

The body cords of the radial tyre run radially from bead to bead, perpendicular to the direction of travel. This radial ply body provides flexible sidewalls that effectively cushion road shock with a minimum of cross ply friction (and heat) since the ply cords don’t criss cross. Two or more stablizing belts encircle the tyre to add support to the body and to help hold the tread grooves open for effective traction. The belt also enables the elements of the tread pattern to resist the normal tendency to squeeze closed during road contact, effectively prolonging tread life.

Diagonal Ply

The diagonal ply tyre has two or four layers of crisscrossed body plies. This conventional construction provides flexibility and two directional strenght in both tread and sidewall areas. It is a very serviceable construction and one that has been a standard in the tyre industry for many years.

Tread Pattern’s

There are 3 common patterns available in the market, which are as follows

Symmetrical

consistent across the tyre's face. Both halves of the tread face are the samedesign.

Asymmetrical

the tread pattern changes across the face of the tyre. These designs normally incorporate larger tread blocks on the outer portion for increased stability during cornering. The smaller inner blocks and greater use of grooves help to disperse water and heat. Asymmetrical tyres tend to also be unidirectional tyres.

Unidirectional

designed to rotate in only one direction, these tyres enhance straight-line acceleration by reducing rolling resistance. They also provide shorter stopping distance. Unidirectional tyres must be dedicated to a specific side of the vehicle, so the information on the sidewall will always include a rotational direction arrow. Make sure the tyres rotate in this direction or all sorts of trouble’s would start on.

Colored Dots – What’s that all about?

When you are looking for new tyres, you’ll often see some colored dots on the sidewall of the tyre. These dots are there for a reason, but it’s more for the tyre fitter than for you to benefit. The dots on the sidewall typically denote uniformity and weight. It’s impossible to manufacture a tyre which is perfectly balanced and perfectly manufactured in the belts. As a result, all tyres have a point on the tread which is lighter than the rest of the tyre – a thin spot. Its fractional you’d never notice it unless you used tyre manufacturing equipment to find it. When the tyre is manufactured, this point is found and a colored dot is put on the sidewall of the tyre corresponding to the light spot. Typically this is a yellow dot and is known as the weight mark or the lightest part of the tyre. The yellow dot should end up aligned to the valve stem on the wheel and tyre combo. Every wheel has a valve stem which cannot be moved so that is considered to be the heavy balance point for the wheel.

What if both dots are present?

Generally speaking, if you get a tyre with both a red and yellow dot on it, it should be mounted according to the red dot – i.e. the uniformity mark should line up with the dimple on the wheel rim, and the yellow mark should be ignored.