All tyres feature a coding system that explains their technical capabilities. Built into the sidewall,
this code provides information on the tyre's construction, size, load carrying capaicty and speed
A = Section width of the tyre (in millimetres)
In this example it shows that the tyre is 305mm wide.
B = Aspect ratio (percentage of width)
In this example the ratio is 30%.
C = Rim diameter (in inches)
In this example it shows that the rim is 19" in diameter.
Tyre wear is caused by a combination of factors, including tyre construction and quality, weather, road structure, and air pressure. Of all these factors, air pressure is most controllable by users.
Regular tyre rotation extends the life of your tyres, saving you time and money. For rotation, each tyre and wheel is removed from your vehicle and moved to a different position. This ensures that all of the tyres wear evenly and last longer.
How Often? If no period is specified in your owner's manual, the tyres should be rotated every 10,000 kilometres.
Proper alignment ensures that your vehicle handles correctly and will help increase the life and performance of your tyres. Failure to keep your vehicle's wheels properly aligned can result in: excessive tyre wear, irreparable tyre damage, excessive fuel consumption and unsafe handling.
Tyres should be checked monthly for signs of irregular wear in both tread and shoulder areas. Irregular wear may indicate under-inflation or tyre damage, or the need for wheel alignment or suspension repairs. A wheel alignment is also mandatory when a replacement set of tyres is fitted to a car.
Three key elements involved in wheel alignment that affect the vehicle's performance are:
The angle between a perpendicular line and a line drawn through the centerline of the tyre when the vehicle is viewed from the front. Camber helps distribute the vehicle's weight across the tyre contact patch during cornering for reduced tread wear and is used to fine tune a vehicle's handling characteristics. Incorrect camber causes uneven tyre wear, poor steering and vehicle stability, and vehicle pull.
The angle between a vertical line and a line drawn through the center of the ball joints (steering axis) when the vehicle is viewed from the side. An improper caster can cause hard steering, increased road shock, reduced straight line stability and cause the vehicle to pull one side or the other. A positive caster helps maintains directional control of the vehicle, helping to return the vehicle to a straight position when cornering, and helps compensate for the crown on a road. Most cars are engineered with a positive caster.
The angle between a line through the center of a vehicle and lines drawn through the centerlines of the tyres when the vehicle is viewed from above. Toe alignment is the most critical to tyre wear. Incorrect toe results in rapid and uneven wear.
Incorrect balance is the largest cause of vehicle vibration. A wheel is out of balance when one area is heavier or lighter than the rest. This can cause uneven treadwear, increased vibration, and increased stress on the front-end parts that may cause them to wear prematurely.
You should have your wheels balanced and aligned:
whenever a tyre is replaced
at the first sign of vibration or irregular treadwear
when a balance weight is moved or removed
whenever you purchase new tyres
You should check air pressure regularly because tyres function properly only when they have the correct level of air pressure. If the air pressure is low or high, tyre function deteriorates, resulting in tyre damage, and possibly an accident.
Manufacturers' recommended tyre air pressure levels are indicated in your vehicle's user manual or on the inner part of the door. They vary slightly among various manufacturers.
When driving for an extended period of time, it is recommended that the air pressure be upwardly adjusted by about 4 psi.
Purchase a good pressure gauge and avoid often unreliable gas station gauges.
Always look for bulges, cracks, cuts, penetrations and abnormal tyre wear, particularly on the edges of the tyre tread, which may be caused by misalignment or under inflation. Also check spare tyres.
Have an experienced tyre technician immediately inspect the tyre if any such damage is found. Continuing to use a damaged tyre could result in tyre failure causing serious injury or even death.
Factors that can lead to accidents include:
Shallow Groove Depth
when groove depth reaches 1.6mm, tyres are prone to slip and can easily blow out from hitting sharp objects.
Improper Air Pressure
when used with low air pressure, tyres generate high levels of heat. As a result, rubber and cord separate from each other, the cord is disconnected and the tyre is blown out. Also, the edge of the tyre is quickly worn away, shortening tyre life. On the other hand, when the tyre has too much air it becomes tense and is easily blown out or cut by external impact.
when tyres run with nails, stones or other objects stuck in the tread groove, they can become flat or blow out. If the scar risks reaching the carcass, the tyre must be immediately replaced.
excessive or deficient air pressure and poor car wheel maintenance abnormally wear tyres. Check tyre air pressure, alignment, and rotation regularly, while refraining from improper driving habits such as sudden accelerating, braking and cornering.
uneven load distribution on tyres due to wheel damage may create friction between the rim fringe and the tyre bead part, generating heat high enough to damage the cord and cause tyre blow out.