Tyre lifespan

P

PUG_504_505

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Fellow Frogger
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Apr 8, 2002
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Sydney
As a general rule of thumb, how long should a tyre remain on a car even though the tread may be in good order?

I'm referring to rubber deterioration over the years such as hardening and/or unseen splitting.

I suppose it depends on the quality of the tyre, driving factors and the like but can it be said that a tyre should be changed every 'x' number of years?

__________________________________
Peter.

:peugeot: '83 505 GR
 
I put some 80% worn Michelin MXFs under the house and then put them back on the car when they were about 4.5 years old. They were a completely different tyre after sitting for that long. The rubber had gone rock hard and they had very little grip.

As for tyres cracking up. I've only seen this on tyres over 20 years old (garaged) or 10 years old on tyres left outside. These are just my estimates. My father bought some Michelin XZX tyres for his 203 in 1986 and only replaced them in 2003 before the Redex rerun. They hadn't cracked, but they were rock hard.

I'm starting to think it's best to replace tyres within 3 years of purchase. You don't know how long they've been sitting in a warehouse before you buy them.

I generally factor in the cost of 2 new tyres per year into my financial calcs (I do 20-30,000kms per year).

Dave
 
I agree that 5 years is a good ball park figure. They get very scary in the wet afetr a few years - just ask my friend with his slightly bent 505. The rear tyres are at least 80% good, but utterly useless for traction
 
Thing is if you're at 80% at 5 years, they just won't wear out at all. No point in really waiting, as it'll take you 20 years to get through that much tread after it has hardened that much.
I'm at the 5 year mark on the Yoko A509s on the Micra at the moment and have 2mm left, I'll either sell the car soon or throw some R compounds on there. As it really is getting skitty in the wet...and even in the dry...just the wet is scarier.
 
The UV from the sun is going to be the biggest factor ... protected and nurished tyres will last a long time. But they break down as molicules leave the rubber compound.

Some more rubber history ...


Natural rubber is a naturally occurring polymer is known chemically as 1,4 cis-polyisoprene. The rubber tree (Hevea brasiliensis) is the most common source of natural rubber used today.

Polyisoprene can also be synthesised by polymerisation from its monomer ‘isoprene’ (CH2=C(CH3)CH=CH2). This is a rare example of a natural polymer that we can make almost as well as nature does.

Rubber has been used for centuries by the South American Indians. They most probably were the people who discovered that if latex (a milky fluid that circulates in the inner portions of the bark of many tropical and subtropical trees and shrubs) is dried, it can be pressed into useful objects such as bottles shoes and balls.

Initially in the western world, the new material was merely a scientific curiosity. Some years later the British scientist Joseph Priestley remarked on its usefulness for rubbing pencil marks from paper, and so the popular term rubber was coined. Other applications gradually developed, notably for waterproofing shoes and clothing.

However, it was not until the 1830’s when John Haskins and Edward Chaffee organised the first rubber-goods factory in the United States that the commercial rubber industry really began to flourish.

At the time rubber had many weaknesses. It softened with heat and hardened with cold; it was tacky, odorous, and perishable. In 1834 the German chemist Friedrich Ludersdorf and the American chemist Nathaniel Hayward discovered that the addition of sulfur to gum rubber lessened or eliminated the stickiness of finished rubber goods. In 1839 the American inventor Charles Goodyear, using the findings of the two chemists, discovered that cooking rubber with sulfur removed the gum's unfavourable properties, in a process called vulcanisation.
Vulcanised rubber has increased strength and elasticity and greater resistance to changes in temperature than unvulcanised rubber; it is impermeable to gases, and resistant to abrasion, chemical action, heat, and electricity. Vulcanised rubber also exhibits high frictional resistance on dry surfaces and low frictional resistance on water-wet surfaces. The vulcanisation process remains fundamentally the same as it was in 1839.

With the invention of the bicycle, the motor car and the pneumatic rubber tyre, demand for rubber grew rapidly. By 1900 more than 40,000 tons were used each year. Today the world’s natural rubber use is over 4 500 000 tons per annum.

The economic competition from synthetic rubber has stimulated research and development in natural rubber by increasing productivity in the field, improving consistency and quality of the product and packaging, and developing natural rubbers with specific properties.

Increased productivity has been achieved by increasing the produce of the trees by cross-pollination of high-rubber-producing clones of the rubber tree (Hevea brasiliensis), use of chemical stimulants, and better tapping and collection methods. These methods have proven particularly successful on Asian estates where over 90% of the world’s supplies are produced, Malaysia being the largest producer.

With improved productivity and better processing methods and controls, much better quality and consistency have been obtained. This has made possible the development of Standard Malaysian Rubbers (SMR) to meet specifications on a number of properties including dirt & ash content, viscosity, and copper & manganese content.

A number of modified forms of natural rubber have been developed to suit particular conditions including the following; superior processing, oil extended, special tyre rubber, deproteinised, pellet form and chemically modified.

Despite synthetic rubber having the larger share (over 75%) of the worldwide rubber market, natural rubber continues to have high demand, due to its better elasticity, resilience and heat transfer properties.

Natural rubber, harvested as latex undergoes a number of steps before it is ready for use.

The first process is tapping. This is where the tree is partially cut through and latex exudes from the wound into a small cup hung at the base of each cut and dries to produce a rubbery film. Rubber trees are tapped about once every two days, yielding a cupful of latex, containing approximately 50 grams of solid latex, each time.

After the collection of the tapped latex, the rubber is taken to a receiving station where it is strained into holding tanks prior to being trucked to a factory for processing. In the factory, rubber is recovered from its mixture by coagulation with formic acid & water. This causes the suspended rubber particles within the latex to clump together forming crumbs that resemble curds of milk.

The crumbs are washed in water, then air or smoke dried between rolls, and compacted into bales 67cm x 33cm x 18cm in size and weighing 33.3kg.

The blocks are wrapped in polyethylene sheets and packed into one-ton crates, which are taken to a warehouse (products fabricator), followed by a shipping dock, ship/plane and finally put to use.

In order to be made into useful products, raw polyisoprene (synthetic or natural) must be modified by a number of additives. With the adding of various substances to raw rubber different types of rubber are produced to suit different conditions. Styrene-butadiene rubbers (SBR) are one of the most widely used and important types of synthetic rubbers in the world. These rubbers are made by emulsion polymerisation of butadiene and styrene in a set ratio (usually 1:3) with the raw rubber. SBR is weak and unusable without reinforcement by carbon black in the rubber, but with carbon black it is strong and abrasion-resistant. Like natural rubber, it is swollen and weakened by hydrocarbon oils and attacked by atmospheric oxygen and ozone. As a result of its excellent abrasion resistance, SBR is widely used in automobile and truck tyres, more so than any other
synthetic rubber. Other common types of synthetic rubbers with additives include Butyl Rubber, Nitrile Rubber & Neoprene. Just about all rubbers are vulcanised or toughened by some means before put to use. Vulcanisation is the final process of commercial rubber manufacturing whereby the raw rubber mixture (essentially plastic) is converted to an elastic state by cooking a chemical with rubber, giving vastly improved strength and durability.

The majority of products are vulcanised with sulfur, however in some cases metal oxides or peroxides are used. Vulcanisation occurs between 125 – 175ºC in a mould held closed by a hydraulic press.

Natural rubber is produced by a biocatalyst called Hydroxynitrile lyase (2-hydroxyisobutyronitrile acetone-lyase), which is a protein found in the latex of all trees producing natural rubber. Synthetic rubber is produced industrially by Zieglo-Natta polymerisation, which is a method of vinyl polymerisation. The reaction uses a titanium chloride catalyst (TiCl4), triethyl aluminium (EtAl3), and an isoprene monomer.

Rubber that has not undergone the vulcanisation process (see "Progress Made In Development") has few practical uses because of its poor heat resistance and high plasticity. It is used for cements, adhesive, insulating, friction tapes and for crepe rubber used in insulating blankets and footwear.

On the other hand, vulcanised rubber has numerous practical applications because of its desirable properties. Vulcanisation improves rubber’s:

Heat & abrasion resistance
Elasticity
Strength & durability

Vulcanised rubber’s excellent abrasion resistance makes it valuable for the treads of vehicle tyres, conveyor belts (soft rubber), pump housings and piping used in the handling of abrasive sludges (hard rubber).

The flexibility characteristics of vulcanised rubber make it suitable for use in hoses, tyres, and rollers for a wide variety of devices ranging from domestic clothes wringers to printing presses.

Its elasticity makes it suitable for various kinds of shock absorbers and for specialized machinery mountings designed to reduce vibration. Being relatively impermeable to gases, rubber is useful in the manufacture of articles such as air hoses, balloons, balls, and cushions. Rubber in the form of latex is also used to make condoms.

The resistance of rubber to water and to the action of most fluid chemicals has led to its use in rainwear, diving gear, and chemical and medicinal tubing, and as a lining for storage tanks, processing equipment, and railroad tank cars.

With their high electrical resistance, soft rubber goods are used as insulation and for protective gloves, shoes, and blankets. Hence, hard rubber is used for articles such as telephone housings, parts for radio sets, meters, and other electrical instruments.

The coefficient of friction (resistance to movement) of vulcanised rubber, which is high on dry surfaces and low on wet surfaces, leads to the use of rubber both for power-transmission belting and for water-lubricated bearings in deep-well pumps.

The future development of the rubber industry will be based upon the integration of three distinct uses of natural rubber - latex, heveawood (the wood that is contained in the rubber tree) and rubber-based products into a single entity. The production of natural rubber will be sustained at 750 billion tonnes per year from about 6 million hectares of rubber areas, to feed the downstream processing and manufacturing of higher value-added rubber-based products for exports. Replanting of rubber trees will also be undertaken as part of the reforestation programmes for both latex and heveawood which is gaining popularity in the furniture industry.

With crude oil resources on Earth decreasing steadily, the production of synthetic rubber may not be as important in the future as it is today. This factor could eventually lead to all rubber being extracted from the rubber tree and other trees containing latex. It is also possible that polyisoprene could be used as a basis for making other alkanes and alkenes. The double bond present in the polyisoprene could be taken advantage of by making ethene. However, producing ethene this way could initially be very costly.

Research & development efforts will be directed towards developing new forms and uses of rubber and rubber products, mechanisation in farming operations and propagating high latex producing clones. Efforts to implement the transfer and assimilation of technology especially the labour-saving extraction techniques will be intensified and accelerated.

One of the biggest environmental concerns in the rubber industry is the inability to breakdown tyre rubber. Tyre rubber is the most important practical application of the material in the rubber industry. The inability to break down tyre rubber causes many problems for fire fighters in tyre fires also. After uncured rubber is mixed with sulfur in the vulcanisation process, cross-links are formed, stiffening the material and improving its elasticity. The problem at this point is that the material doesn't have a lot of chemical reactivity left.

It's a very stable chemical state, which makes for a good tire, but something that's very difficult to recycle, because if you just grind it up and try to mix it with uncured rubber, there's no way for bonds to be formed.

Prior to 1986 there was virtually no scrap tire recycling industry and instead whole tyres were land filled. Today, used tyres are turned into crumbed rubber and used for civil engineering, automotive parts & accessories and recently it was found that up to 10% recycled rubber could be used in new tyres without reducing performance.

Processing of rubber irrespective of being natural or synthetic causes certain environmental hazards. These include emission of dust or fumes and noise. If proper precautions are taken these problems can be minimised. The main point to be noted here is that it is not the rubber, which is hazardous, but the compounding ingredients, which are added to it. Natural rubber processing industries sometimes cause an additional problem of odour, originating from the ageing of proteinaceous materials. In some cases the unpleasant odours may be carried over into the product. While this is a problem to be attended to by natural rubber producers, it is possible to minimise the problem by using higher grades of rubber.

When environmental issues are considered, it has to be accepted that man causes these problems. The ever-increasing world population is the single most important factor leading to environmental pollution. Any attempt to check population growth is going to have a beneficial influence on the environment. In this context the contribution made by the tiny rubber product, condom, mostly made from latex, has to be duly recognised.

Latex is known to trigger allergic reactions in sensitive individuals from its extractable proteins. Although it is quite a rare allergy, alternative materials (PVC, nitrile rubber etc.) need to be used by people who suffer the allergic reaction on a regular basis.
 
GTI124 said:
Thing is if you're at 80% at 5 years, they just won't wear out at all. No point in really waiting, as it'll take you 20 years to get through that much tread after it has hardened that much.
Click to expand...

Wont get any argument here - its booked in to get them changed (after the front is fixed from the slight bingle - as a result of the tyres). They are just too scary in the wet, have already caused one accident and will take years more to wear out. Plus we got a trade in on them as they have a lot of tread left :D
 
5 years!! thats a long time :eek:

i seem to replace tyres about once a year

must be those nice windy roads i like :roflmao:
 
thanks XTC206, I'm sure I'm the only person who read that!

I saw the rubber plantation of Vietnam's old DMZ when I was there a few months back. It's such a manual process harvesting natural rubber. But they're very cool to be under in the hot sun.
 
GTI124 said:
thanks XTC206, I'm sure I'm the only person who read that!
I saw the rubber plantation of Vietnam's old DMZ when I was there a few months back.
Click to expand...
It was a bit long .... Oops .. interesting reading though.

I saw many in Northern Malaysia ... one of my uncles (by marriage) owns some

- XTC206 -
 
XTC206 said:
Latex is known to trigger allergic reactions in sensitive individuals from its extractable proteins. Although it is quite a rare allergy, alternative materials (PVC, nitrile rubber etc.) need to be used by people who suffer the allergic reaction on a regular basis.
Click to expand...

although true allergies to latex are rare, sensitivity to latex is quite common among health care workers who are exposed to latex on a daily basis. and those alternative materials (PVC and nitrile) are horrible in comparison with good quality latex.
 
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