Tyre Tips And Tyre Care.

[cfc1]

After checking a few websites I have deceided to post a topic quoting some tyre care and tips for you all.

The Golden Rules

Check air pressures in all tyres regularly.

It is preferable that this check be made weekly, when tyres are cold, and using a gauge known to be accurate.

Avoid hard braking and sudden acceleration.

Tyres may wear quickly if consistently subjected to hard braking or rapid acceleration. Adopting a conservative driving style will maximise tyre life.

Use care when parking to avoid tyre damage.

Many impact fractures occur in the sidewall area of the tyre. rather than the tread.

Careful parking will reduce damage to tyre sidewalls that can occur through contact with kerbs.

Ensure that tyres have more than 1.6mm of tread.

Most new tyres have about 8-9 mm of tread pattern when manufactured but when the tread wears down to less that 1.6mm, the tyre may be unsafe to use in wet conditions and should be replaced as soon as possible. Tyres have Tread Wear indicators in their tread pattern which show as lines across the tread when reduced to 1.6mm... this is also the legal limit, if your tyres are below 1.6mm you are breaking the law.

Do not use sealants to repair punctures.

After a puncture, tyres should be inspected internally to assess what damage has occurred, and whether the tyre sill complies with minimum safety standards.

While sealants may be acceptable as a temporary emergency measure after a puncture has occurred, they often do not fully inflate the tyre and accordingly the vehicle should be driven and reduced speeds until the tyre can be changed or permanently repaired. Sealants should not be used as preventative measures. the use of sealants may invalidate tyre warranties.

Understanding Tyre markings

Tyres have a code system moulded into their sidewall which allows you to understand their technical capabilities.

This code provides information on the tyre's construction (e.g. radial), its size, its load-carrying capacity and its speed rating.

For example, the code on a common fitment for cars is:

205/65R15 95H

205 - indicates the nominal section width of the tyre in millimeters (205mm).

65 - indicates its aspect ratio, a comparison of the tyre's section height with its section width (65 indicates the height is 65% of its width).

R - indicates radial ply construction.

15 - indicates the nominal diameter of the wheel rim (15 inches)

95H - is a symbol indicating the maximum load capacity and speed at which the tyre can be safely operated, subject to the tyre being in sound condition, correctly fitted, and with recommended inflation pressures (95 represents a maximum load of 690kg per tyre; H represents a maximum speed of 130mp/h).

Tyre speed symbols..

N - 87mph

P - 93mph

Q - 99mph

R - 106mph

S - 113mph

T - 118mph

H - 130mph

V - 149mph

W - 168mph

Y - 189mph

ZR - 149mph

Tyre load ratings..

The maximum weight of the vehicle shouldn't be more than the weight the tyres are designed to carry.

Tyres with a load rating code of 91 (615KG) shouldn't be fitted to a vehicle that weighs in excess of 2460KG.. 616 x 4 = 2460.

Tyre rotation

Tyre rotation is vital to achieving even tread wear and long tread life. Rotation is necessary because of the uneven wear characteristics of each wheel position on the vehicle. A good example is Front Wheel Drive vehicles which places braking, steering and driving forces on the front axle tyres. Rear axle tyres only receive braking forces resulting in a much faster wear rate for the front axle tyres. Tyre rotation for these vehicles therefore becomes very important for optimum tyre life.

Tyre rotation should be undertaken every 5,000 to 8,000 kilometres:

EVEN IF THERE IS NO SIGN OF UNEVEN WEAR

Cross Rotation

The "Cross Pattern" provides the best results and can be performed on any Front or Rear Wheel Drive vehicle equipped with 4 non-unidirectional tyres. (Unidirectional tyres must be rotated front to rear only.)

NOTE: Free rolling axle tyres are crossed and installed to the drive axle, while the drive axle tyres are brought straight to the free rolling axle (without crossing).

Vehicles equipped with permanent 4-Wheel Drive and those with "on Command" 4-Wheel Drive and driven mainly in 4-Wheel mode, are best suited to a four tyre cross rotation. With this pattern, tyres from both axles are crossed and installed on the opposing axle.

Straight Rotation

Straight Rotation was developed in the early years of radial tyres. This rotation method simply replaces the front to rear and rear to front.

5 Tyre Rotation

If the vehicle owner has a regular tyre as a spare tyre and wishes to include it in the tyre rotation process, the proper procedure is to use the appropriate rotation pattern shown for 4 Tyre Rotation, BUT insert the spare in the right rear position. Place the tyre which would have gone to the right rear in the trunk as the new spare.

Note: Never include a temporary spare tyre in the rotation.

IMPORTANT: Unidirectional treads are designed to perform in the direction denoted on the tyre sidewall only. They must always be rotated front to rear - despite the type of vehicle they are installed on - so the direction of the revolution does not change.

Temporary Spares

Temporary use spare tyres or space savers are specially constructed spare tyre and rim combinations provided by vehicle manufacturers as standard equipment in many vehicles.

These spares are lighter and smaller than those which you normally see fitted to motor cars.

Temporary use spare tyres are generally recognizable by their unusual design (yellow rim) and compact size.

Some notes to remember when using a Temporary Spare

1. Fit only the temporary use spare tyres provided by the vehicle manufacturer for your vehicle model. (Replacement tyres offered by reputable tyre companies may also be used provided they match the original equipment specifications.)

2. Temporary use spare tyres are not designed to travel long distances. If you are unsure of the condition of the space saver spare tyre, check it before driving the car.

3. Do not attempt to fit a temporary use spare tyre to any other rim.

4. Use the temporary use spare tyre strictly in accordance with the vehicle manufacturer's instructions.

5. Carefully observe the manufacturer's recommendations for any limits on speed, tyre pressure, load and safe travel distance. Note inflation pressure will not be the same for the temporary spare as the primary tyre. This information can be found either on a placard near the spare tyre or in the vehicle handbook.

Aspect ratios.

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 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 legislation, and that tyre load and speed ratings equal or exceed the minimum allowed for that vehicle in your state.

Inflation pressure.

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.

Wheel alignment.

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 tyre centre will be able to inspect the tyres fitted to your vehicle and advise you as to whether a wheel alignment is required.

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.

Wear life.

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.

Valve maintenance.

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.

[Kev Mc]

Another very useful post, good work

I always look at the previous guide you did when I need to know anything about tyres, it's great

[PaulT]

Mainly good stuff, but I never rotate the tyres. Can't see how there can be any benefit to that.

Also, tyres have different recommended inflation pressures depending on the speed at which they are expected to be used. These should be in your car handbook. I normally over-inflate on track days too, to protect the tyres from heat build-up.

Paul.

[cfc1]

If you look in your hanbook it will tell you what the correct load and speed ratings are for your particular vehicle. Tyre pressures however remain the same, If you are driving at high speeds, then you would put on a tyre with a speed rating to suit the speed at which you will be driving.

The faster you drive the faster the tyre flexes, thus generating more heat. An excess of heat build-up in a tyre can seriously damage it, or over prolonged periods of time destroy it. Therefore it is important to get the tyre that best suits the type of driving you do. The higher the speed rating on the tyre the less flex there is on the sidewall, less flex = less heat.. and less heat lowers the chances of a blowout.

To much or too little pressure WILL reduce the tread to road contact as shown in the picture above.

[PaulT]

Paul.

[Karma Supra]

I also never rotate tyres... for starters most of my cars have wider tyres at the back ;) I also agree with Paul, the supra has 4 different tyre presures IIRC (on the sticker in a glove box) low load low speed, low load high speed, high load low speed and high load high speed, that is before you get into the different types of engine!

Good post though.

My spare wheel doesn't fit over my front brakes :(

[cfc1]

Also, tyres have different recommended inflation pressures depending on the speed at which they are expected to be used.

Paul.

It's not so much the tyres that have different pressures for diffetrent speeds.. but more the car the tyres are fitted to remember that this is a "general" post and not car specific, and as such should only be used as a guide. (maybe I should have put that at the start ) I could have spent day's typing this up if I wanted to put all sorts of clauses and sub-clauses for all different car types and road conditions etc etc. but tried to keep the info to a minimum with as much general info as possible.

Obviously the more info the better, so if anyone else wants to add more.. thats what the forum is for

[GIDDLEPIN]

I only ran a couple of hundred yards to a safe place after a puncture in Annes car and that was enough to bugger the tyre :(

Nice post Davey