Tyre profiles have changed considerably in recent years because of changes in vehicle styling and demand for increased vehicle performance. Today's tyres have a squat appearance, rather than the tall, narrow look of yesteryear. The aspect ratio is a comparison of the tyre's section height with its section width (45 indicates the height is 45% of its width).
Upgrade to low profile tyres.
An upgrade to a tyre with a lower profile size than the original will generally improve the vehicle's steering response, handling characteristics and appearance. There are options available to change the rim width and diameter, which will maintain similar specifications to the original tyre fitment. For more information, talk to your local Bridgestone Tyre Centre to ensure the upgrade is suitable for your vehicle.
NOTE: When fitting new replacement tyres and/or wheels, ensure any alternative to the original tyre and wheel fitment complies with relevant state legislation, and that tyre load and speed ratings equal or exceed the minimum allowed for that vehicle in your state.
Deterioration and damage.
Breakdown of tyre casings can arise from prolonged under-inflation, overloading or running on a nearly flat tyre. Casing fractures can occur through severe impacts with kerbs, pot holes or roadway objects - even when travelling at low speeds.When a tyre has had a severe impact, it should be removed as soon as possible for internal examination to assess for damage. Refer to the images below for examples of tyre damage.
For heavy loads or sustained high-speed operations, inflation pressures must be increased according to recommendations on the tyre placard.
It is air that carries the total load of the vehicle and passengers, so correct inflation pressure is essential to ensure the integrity of the tyre and the safe handling of the car.
Pressures should be checked regularly, preferably weekly, when tyres are cold. Never reduce air pressure when tyres are hot from driving because it is normal for pressures to increase while tyres are hot. After checking pressures, ensure that valve caps are replaced as these are the primary seal. Use only sealing-type valve caps.
Over inflation reduces the ability of the tyre to absorb road shocks, resulting in a much harsher ride. In fact, excessive over inflation may lead to impact fracture, or other casing failures. Over inflation will also cause excessive wear of the centre of the tyre. This will result in premature removal of the tyre. Check the tyre placard for recommended inflation pressures.
Under inflation is a frequent cause of tyre damage. Under inflation causes excessive flexing in the tyre, which builds up internal heat and may eventually weaken the casing. It will also cause rapid shoulder and irregular tread wear. Check the tyre placard for recommended inclation pressures.
Balancing your wheels.
Safety is the main reason for balancing the wheels and tyres on your vehicle. Balancing will help ensure a smooth, vibration free ride as well as improving tyre life.
When the wheels on your car have an imbalance, the most notable effect is that the steering wheel moves up and down in your hands or the seat vibrates. This can be extremely frustrating and especially tiring on a long trip, which may result in the driver's judgement being impaired. In a mishap, a vibration that is excessive may result in some suspension damage if the cause of the vibration is not corrected for a long period of time. As the tyre and wheel assembly is vibrating, the contact pressure of the tyre on the road varies, which can cause irregular wear and will in turn, result in premature tyre removal.
The wheels should be balanced when new tyres are fitted, any time that the tyre is removed from the rim and at regular intervals to take into account any variation in tyre balance from irregular wear.
Correctly wheel aligning your vehicle will ensure that it drives straight down the road. Correct wheel alignment will also ensure that the tyres on your vehicle wear evenly and are not removed prematurely as a result of irregular wear. This will also increase fuel economy.
Wheel alignment should occur upon fitting new tyres to your vehicle and for every 10,000km after. Your vehicle should be wheel aligned at regular intervals throughout the life of the tyre, especially when components have been replaced in the front or rear suspension or if the vehicle has hit anything (e.g. a kerb). Your local Bridgestone Tyre Centre will be able to inspect the tyres fitted to your vehicle and advise you as to whether a wheel alignment is required.
All cars manufactured since 1973 have a placard containing information about correct tyre use. This placard indicates recommended tyre sizes, correct inflation pressures for front and rear tyres under normal driving, heavy loads and sustained high-speed operation. The placard is usually contained in the glove box, on the driver's door pillar or under the front bonnet.
Radial ply tyres.
Most modern passenger car tyres have a radial ply construction. This means that the casing cords run radially from bead to bead and belt cords run directly under the tread. Radial ply tyre construction provides strength and stability to the tyre casing along with long tread life, excellent handling and resistance to punctures.
Repair or replace.
Some tyres are damaged so badly that they must be discarded. Tyres that should never be repaired include those with tread or casing separation; fabric chafer damage which would reduce the tubeless air seal; broken, kinked or exposed bead wires; flex breaks; presence of an internal liquid sealant with any penetration damage through the inner liner; tread depth below 1.6mm; cracks which extend into the tyre fabric; open liner splices which show exposed cords; liner and first ply showing evidence of having been run flat, under inflated or overloaded.
It is recommended that repairs should be undertaken only by qualified tyre technicians, because sometimes tyres with apparently minor external damage have actually sustained unseen but serious internal damage.
Tubed or tubeless.
Most modern passenger car tyres are tubeless, but some tubed type tyres are still available. Old or excessively repaired tubes should be avoided because they can lead to slow or sudden deflation and damage the tyre. Tubed tyres must be fitted with the correct size tube.
Many second-hand tyres are imported into Australia after having been used in overseas countries. Because they enter the country without being tested to any standard, a significant proportion of these second-hand tyres are defective. Many of these tyres provide only a short working life in Australia because they have already travelled thousands of kilometres in their country of origin. They also add to Australia's waste disposal problems.
The rate of tread wear depends on factors such as vehicle speed, load, braking, cornering, acceleration, inflation pressures, wheel alignment, road surface, climatic and even geographical conditions. A conservative driving style will help to prolong tyre durability.
Tyre valves maintain the air pressure in the tyre. It is recommended that the valve be replaced when new tyres are fitted. Valve caps are the primary air seal, and protect the valve from dust, grit and water. Soft plastic dust caps which have no sealing ability are not recommended.