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Continued from the tyres subject ….

Wheel Balance

Out of balance wheels can reduce life of tire by thousands Kms, because constant bouncing of an out-of-balance tire results in excessive tire wear. Tire and wheels should be balanced when new tires are mounted on the wheels for the first time, when the tires are installed on the existing wheels after a repair or any other time a tire is dismounted, wheel balance should also be checked,  if vibration or unusual tread wear is detected. An unbalanced wheel and tire assembly may create an annoying vibration when you drive on a smooth road and may result in irregular tread wear.

Wheel Alignment

Misalignment of wheels in the front or rear, improperly operating brakes or shock absorbers, bent wheels, worn bushings and other mechanical problems cause uneven and rapid tread wear and should be corrected by a qualified mechanic. Front-wheel-drive vehicles, and those with independent rear suspension, require special attention with alignment of all four wheels. These systems should be checked periodically as specified by the vehicle owner’s manual or whenever you have an indication of trouble. A bad jolt, such as hitting a pothole, can throw your front end out of alignment even if you had it checked an hour earlier. Such an impact can also bend the rim, causing a loss of air pressure, and damage your tires with little or no visible external indication.

A correct wheel alignment can save you plenty on the cost of tyres. Badly aligned suspensions wear tyres out rapidly and are also unsafe, as they affect your cars handling. A wheel alignment is recommend at the time of fitting new tyres and at regular intervals . Wheels which are only a fraction out of alignment can scrub or drag along the road instead of rolling along it.

What is Wheel Alignment

Camber is the measurement in degrees of the angle of the tyre from vertical when seen from the front or rear.

Castor is the relationship between the steering axis and tyre vertical. Zero castor is when the steering axis is vertical. When the steering axis is tilted backwards (by far the most common design) it is said to have a positive castor. Unequal castor from side to side causes steering pull to the side with the least amount of positive castor.

Toe-In is the difference in distance between the front of the wheels and the rear of the wheels. Most vehicles have some inward pointing of the wheels when stationary, the wheels become approximately parallel when the vehicle is in motion.

Tire Rotation

Sometimes irregular tire wear can be corrected by rotating your tires. Consult your car owner’s manual, the tire manufacturer or your tire dealer for the appropriate pattern for your vehicle. If your tires shows uneven wear, ask your tire dealer to check for and correct any misalignment, imbalance or other mechanical problem involved before rotation.

Sometimes front and rear tires on a vehicle use different pressures. After rotation, adjust individual tire air pressure to the figures recommended by the vehicle manufacturer for the new locations—front or rear—as shown on the tire placard in the vehicle.

The purpose of regularly rotating tires is to achieve more uniform wear for all tires on a vehicle. Before rotating your tires, always refer to your individual owner’s manual for rotation recommendations. If no rotation period is specified, tires should be rotated approximately every 9000 to 10000Km.

However, rotate your tires earlier if signs of irregular or uneven tire wear arise, and have the vehicle checked by a qualified technician to determine the cause of the wear problem. The first rotation is most important.

Popular Rotation Patterns

Do not include a “Temporary Use Only” spare tire in any of the rotation patterns shown. If you have a matching full-size tire as a spare and wish to include it in the rotation process, use the “five wheels rotation” pattern. Insert the spare in the right rear position and place the tire that would have gone on the right rear in the trunk as the new spare. Some tires cannot be rotated in the manners described. Such tires include uni-directional tires and tires with asymmetric tread designs. Also, some vehicles may have different-sized tires mounted on the front and rear axles, and these different-sized tires also have rotation restrictions. Check your owner’s manual, or with your tire dealer or tire manufacturer, for the proper rotation recommendations for these special cases.

Replacing tyres

When you decide to replace tyres you have to know which type of tyres you need to replace with. The best choice is the original type which comes with your vehicle when you bought this new and if you think that you need to go for another type you must distinguish between the two main types of the tyres used in general, cross-ply and radial ply.

Cross-ply tyres: the cords making up the structure of the tyre run diagonally across it,with alternate layers at opposite angles, trellis structure.

Radial -ply: the cords run at the right angles across the tyre resulting in thinner and more flexible walls. The tread of a radial-ply tyre gives extra grip in the wet road conditions.

Mixing tyre types: its not safe to mix cross-ply and radial-ply tyres on your car use all the tyre of same type. In many countries its an offence to mix the both type on the same axle.

 Cont ….till next edition…