154 -160 BARRACK RD, CHRISTCHURCH BH23 2BD
For many motorists, tyres barely rate a second thought, until one goes flat or they need to be replaced.
However, given a little care and attention, tyre life can be maximized and overall vehicle performance, fuel consumption, occupant safety and comfort can all be improved. Here are a few tips to help you achieve this, as well as some background information that will help you select the right tyres for your car when it comes time to replace them.
How To Read a Tire
Your tire contains very useful information molded into the sidewall. It shows the name of the tire, its size, whether it is tubeless or tube type, the maximum load and maximum inflation, the important safety warning and much other information. I hope you find this handy information usefull.
Shown here is the sidewall of a popular "P-metric," speed-rated auto tire.
Some speed-rated tires carry a Service Description, instead of showing the speed symbol in the size designation. The Service Description, 89H in this example, consists of the load index (89) and speed symbol (H). The H in this case indicates the tire's maximum speed is 130 mph. See the chart below for other speed ratings:
|Rating||MAX SPEED (MPH")|
How long should tyres last?
Tread wear rates are affected by many factors and there are too many variables involved to allow an accurate answer to this question. Some will be in the drivers control but many wont be. Factors beyond the drivers control including road surface, climatic conditions and tyre and vehicle design.
But there are things that the driver can do to influence tyre wear. “Enthusiastic” driving styles, including high speed operation and cornering, harsh braking and hard acceleration all dramatically reduce tyre life.
When is a tyre worn out?
The law requires a minimum 1.5 mm tread depth across the face of the tread normally in contact with the road. To help gauge this, car tyres have tread wear indicator bars moulded across the tread at regular spacings around the tyre. When the tread wears to the legal limit, the wear bar will be level with the tread blocks. The letters TWI are often moulded into the edge of the tyre tread at the wear bar locations.
Its the tread that helps pump the water out from between the tyre and road. Tyre grip on a wet road diminishes considerably as the tread wears down so for continued safe operation they should be replaced before they reach their minimum legal tread depth.
Remember also that cuts or other damage may render a tyre unroadworthy too.
Whats the best brand of tyre?
This depends largely by what yard-stick you measure “best”. For one person the cheapest, longest lasting tyre will be the best. To another, the tyre that offers the most grip is the best, even if it has a fairly short life.
Tyre engineering is about compromises and trade-offs. It simply isnt possible to design a tyre to do everything well. High performance tyres that offer high levels of grip are often quite soft and can have a short life. Similarly, tyres that have chunky tread patterns to displace water can provide high levels of wet grip but are often noisy.
Ultimately youll need to consider whats important to you and discuss your needs with a reputable tyre dealer.
Increasingly, vehicle and tyre manufacturers work together to design a complete vehicle / tyre package. This often means that the tyre is designed specifically to provide the driving and handling characteristics the vehicle manufacturer to trying to achieve. With the tyre being such an integral part of the vehicle it would be sensible, where possible, to stick with the make and model of tyre the vehicle was fitted with when new.
As a general rule though, if you stick to the well-known mainstream brands you shouldnt go too far wrong. Take some professional advice if necessary. For safetys sake, remember you usually dont get anything more than what you pay for and skimping on tyre quality could prove false economy.
What size tyres are right for my car?
The tyre and wheel sizes fitted to your car as original equipment have been chosen by the manufacturer after careful consideration of the vehicles design and likely use. The recommended sizes, speed and load ratings are all shown on the tyre placard and in the owners handbook.
Replacement tyres must have a load rating at least equal to that specified by the cars maker. We recommend fitting tyres with a minimum speed rating at least equal to that shown on the vehicle's tyre placard. However, it is legal to fit tyres with a lower speed rating than shown on the placard provided they have a minimum speed rating of 180km/h.
You must never fit wheels and tyres of different size or profile to the same axle except when a 'space-saver' or 'emergency-use' spare tyre supplied by the vehicle manufacturer is in use. These tyres are for emergency use only and information regarding speed and any other restrictions that apply to their use is contained in the owner's handbook, on the spare wheel and on the tyre placard.
For information on fitting tyres to your car other than those recommended by its maker, see the section on “Alternative Wheels and Tyres” in this fact sheet.
Caring for your tyres
Correct inflation pressures are essential if your tyres are to deliver maximum life and performance.
Under-inflation causes excessive tyre flexing and heat build-up and is the number one reason behind catastrophic tyre failure or “blow-outs”. Under inflation also causes accelerated tyre wear rates, uneven wear patterns, heavy steering and increased fuel consumption. Over-inflation can result in a harsh ride, uneven wear patterns and increased risk of tyre impact damage.
Incorrect inflation pressures will also reduce the all-important tyre “footprint” on the road, resulting in impaired handling and braking.
So whats the correct pressure?
All vehicles built since 1973 will be fitted with a tyre placard that lists the specifications of the original tyres fitted to the vehicle and the correct inflation pressures. It will be located in an easily accessible spot such as the glove box lid, fuel filler flap or the drivers door or opening. The information will be contained in the owners handbook as well. Diagram 1 shows an example of a tyre placard.
The pressures shown for normal use are the minimum suitable for average suburban driving with minimum loads. For increased load carrying or sustained high speed driving (around 100km/h for more than 1 hour) tyre pressures should be increased as advised on the placard or, if not shown, as recommended by a reputable tyre dealer.
Remember, the pressures shown on the placard are the minimum allowable cold pressures and you should not allow your cars tyres to drop below them. In fact its acceptable, if not wise, to keep them inflated to the high load / speed pressure listed on the tyre placard or suggested by a tyre dealer.
Tyre pressures should be checked cold as it is normal for pressures to increase as the tyre heats up from driving. Dont bleed air from hot tyres to obtain the recommended cold pressure. Its not a bad idea to have your own tyre gauge for doing your regular (at least once a fortnight) pressure checks – and dont forget the spare. If you notice any significant pressure drop, especially on just one tyre, have the cause checked out – you might have a leak – possibly from a puncture or defective valve.
Remember to replace the valve dust caps after checking tyre pressures. Its important they are fitted to all your tyre valves as they help seal air into the tyre and exclude dirt, which may cause the valve to stick or leak.
Tyre pressures are measured in Kilopascals (kPa) or in pounds per square Inch (PSI).
All about wheel balancing
Commonly known as tyre balancing, wheel balancing, is the process of evening out the weight of the combined tire and wheel assembly so that it spins in a smooth motion, but at a high speed.
Balancing involves the assembly of the wheel and tyre on a balancer, thus centring the wheel and spinning it to determine the placings of the weights.
Traditional spin balancing
In order to balance a wheel and tyre assembly, we put them on a balancing machine- there are numerous ways of balancing tyres manually, but using a balancing machine is a lot more efficient and effective.
The high speed the machine spins the wheel in, helps determine the the heaviest point and signals the operator where and how many weights need to be placed on the adjacent side to compensate.
Three important things to know about balancing are:
1. Balancing is necessary – If there is a weight imbalance in every wheel or tyre, assembly is inevitable.
It is rare that an assembly will come out perfectly balanced; one of the other things the machine does is discover a balance as well as an imbalance.
2. Balance changes over time – The balance of the tyre will have a dynamic change over time as the tyre wears down.
This is where rebalancing should be considered, as getting your tyres rebalanced at least once within the said life of the tyres, will extend their lifetime.
3. Balancing only fixes the balance – Balancing is unable to prevent vibrations from a bent wheel, as it can only compensate for weight for differences.