What is the difference between a Radial Tyre and a Bias Ply Tyre?



Passenger car tyre is a steel-rubber-fabric component that surrounds a wheel's rim.  According to their construction car tyres are divided into bias and radial. To understand the difference between these types of tyres, it is necessary to study their features, benefits and drawbacks.

What is a Bias Ply Tyre?

This type of tyre consists of a rubber-fabric casing and air-tight inner tube. In working condition, the inner tube is inflated under a certain pressure. The sidewall of a bias ply tyre is a symmetrical construction that consists of an even number of crossed plies.

A bias ply tyre has a structure in which the ply cords extend to the beads and are laid at alternate angles substantially less than 90° to the centerline of the tread. Cord is usually made of synthetic fabrics (nylon, polyether etc.). A bias ply tyre is more resistant to impacts and cuts. When running a rough road, its carcass demonstrates such features as strength and endurance.

Benefits and drawbacks of Bias Ply Tyres

However, this tyre has its drawbacks. Among the most obvious are the following:

  • significantly shortened operational lifetime;
  • lower load carrying capacity;
  • low wear resistance;
  • relatively weak grip with asphalt road ;
  • more difficult car handling;
  • carcass made of synthetic materials that have a lower thermal conductivity;
  • relatively large weight.

Basically, bias ply tyres are made for poor road conditions (heavy-duty tyres with adjustable pressure, and others). Today they are used for special-purpose equipment (excavators, tractors, etc.) and trucks.

What is a Radial Tyre?

In the radial design, the threads of the carcass cord are not crossed, but arranged radially (meridionally), i.e. the cord threads are directed parallel to each other. The number of cord layers can be odd. This tyre can be tubed or tubeless. The sidewall of a radial tyre consists of one or more cord layers with almost parallel threads. Synthetic polyamide fabric that provides greater strength, high elasticity and lightness of the tyre carcass is used. The upper layers of the carcass of these tyres are covered with a belt, for the manufacture of which a strong steel cord is used. Usually passenger car radial tyres are tubeless. In tubeless tyres, an innerliner is used instead of a tube. The shock absorbing ability of a tyre is achieved by tube inflation and tyre flexibility.

Benefits and drawbacks of Radial Tyres

Main benefits of radial tyres are the following:

  • long-term operational lifetime;
  • ability to withstand increased physical stress;
  • ensuring optimal vehicle stability;
  • reduced rolling resistance (this contributes to saving fuel consumption);
  • high thermal conductivity of carcass;
  • good traction with asphalt road;
  • comparatively low weight.

In addition to the advantages, this type of tyres has some drawbacks: relatively high cost, vulnerability of sidewall to mechanical stress and damage.

The difference between a Radial Tyre and a Bias Ply Tyre

After examining all the benefits and drawbacks of both types of tyres, it can be emphasized that radial tyres are different from bias tyres on the following parameters:

  • wear resistance;
  • number of cord layers, raw material, arrangement of threads;
  • lifetime period;
  • number of bead rings;
  • vehicle driving;
  • thermal conductivity of carcass;
  • rolling resistance;
  • load bearing capacity;
  • absence / presence of a tube;
  • scope of application;
  • tyre weight.

Benefits of performance properties of radial tyres over bias ply tyres are obvious, so it is not surprising that they are more in demand on the domestic and global markets. Type of construction is usually indicated in tyre marking, which means that car owners will not have problems with the purchase of suitable tyres.

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