Safety

Proper vehicle safety requires specific attention to tires - to inflation pressure, tread depth, and general tire condition. Over inflated tires can burst when subjected to excessive load due to cornering or ride disturbances. Under inflated tires can suddenly go flat and make the vehicle difficult to control. Excessive tire wear will reduce steering and braking response. Treads worn down to the carcass can also burst due to loss of air pressure.Tire inflation pressure and tread depth should be checked regularly in accordance with the vehicle manufacturer’s recommendations. Certain combinations of cross ply and radial tires on different wheels of the same vehicle can lead to vehicle instability, and may also be illegal. UV light from the sun or even welding equipment can 'age' tires and make them more liable to burst. Ford now recommends that tires in service greater than six years replaced, regardless of tire wear, to reduce the risk of tire failure.

Dangers of aged tires

Research and tests show that as tires age, they begin to dry out and become potentially dangerous, even if unused. Aged tires may appear to have similar properties to newly manufactured tires; however once the vehicle is traveling at high speeds (i.e. on a freeway) the tread could peel off, leading to severe loss of control and perhaps a rollover.

The date of a tire's manufacturer is found on the rim, to the right of the product code. The date code is often found on the inward side of the tire, so if they are already installed on the vehicle, the person has to lie underneath the car with a flashlight to check the dates. The date is a four digit code WWYY, with WW denoting the week (1-52) and YY denoting the year.

Stopping distance

The use of performance oriented tires, which have a tread pattern and rubber compounds designed to grip the road surface, usually has slightly shorter stopping distances. However, specific braking tests are necessary for data beyond generalizations.

Balance

When a wheel and tire is rotated, it will exert a centrifugal force characteristic of its center of gravity. This cyclical force is referred to as balance, and a non-uniform force is referred to as imbalance or unbalance. Tires are checked at the point of manufacture for excessive static imbalance and dynamic imbalance using automatic Tire Balance Machines. Tires are checked again in the auto assembly plant or tire retail shop after mounting the tire to the wheel. Assemblies that exhibit excessive imbalance are corrected by applying balance weights to the wheels to counteract the tire/wheel imbalance.

Bias tire

 (or cross ply) construction utilizes body ply cords that extend diagonally from bead to bead, usually at angles in the range of 30 to 40 degrees, with successive plies laid at opposing angles forming a crisscross pattern to which the tread is applied. The design allows the entire tire body to flex easily, providing the main advantage of this construction, a smooth ride on rough surfaces. This cushioning characteristic also causes the major disadvantages of a bias tire: increased rolling resistance and less control and traction at higher speeds

Radial

Radial tire construction utilizes body ply cords extending from the beads and across the tread so that the cords are laid at approximately right angles to the centerline of the tread, and parallel to each other, as well as stiff stabilizer belts directly beneath the tread. The advantages of this construction include longer tread life, better steering control, and lower rolling resistance. Disadvantages of the radial tire include a harder ride at low speeds on rough roads and in the context of off-roading, decreased "self-cleaning" ability and lower grip ability at low speeds