The Tyre Topic Magazine
Issue 1
July 2008
Who is monitoring your every move The story of a legend An all new G582 tyre Small things can make BIG differences
FOREWORD BY Mr. NAKANISHI
CONTENTS
Industry Update IVMS – Monitoring every move Product Focus G582 – Enhancing service life
4-7
“The important thing is not to stop questioning”
8 - 12
Info Line Are you starving or overfeeding your tyres?
13 - 17
Personal Diary Roy Carver – The legend that revolutionized the industry
18 - 20
Experts Speak Valve caps – Big deal?
21 - 24
- Albert Einstein
Children ask a lot of questions. Why does the sun go down? Is the fish drinking water now? So on... The content of their questions is not the point; the point is they ask a lot of questions as they want to learn more about the things around them. Interestingly when children ask questions that have answers, is a sign
Pure Tech Inflation pressure – Demystified!
25 - 27
Did You Know? Vulcan, the true Iron Man!
of them growing up! Unfortunately as we grow older, we have fewer questions. We get comfortable with what we know. Its not that we are not interested in knowing more, the fact is - we perhaps avoid it since it requires spending more of our ever decreasing time and energy.
Do you have a real question?
Our aim is to provide ‘Real Answers’ to our customers, our own people and anyone related to the tyre
Would you like to contact us or our specialized techies to ask any question? Just send us an email to: realanswers@bridgestone.ae and we will get back to you!
industry. We hope to bring about Real Answers to those issues you face while managing your truck tyres or your truck operations. We hope to contribute in improving your safety, efficiency and reduce your operating costs. So don’t stop asking questions. Send us your questions to our email address and we will try to answer
Trucker’s Hot Spots
them in our subsequent issues under the section “Popular Demand”.
Truckers’ Hot Spots are basically illustrations throughout the magazine that you should look out for. Below is a key for what to find:
In this issue we look at Real Answers from HSE (Health Safety & Environment) official at Petroleum Development of Oman on IVMS (In Vehicle Monitory system).
Real G INTERESTING
Real DEFINITION
We look at our new product G582 and we will also visit the person who brought the tyres back to life! Finally, there are lots of very small things,
even invisible things that can make a big difference. Real FACT
Real EASY TO UNDERSTAND
Find out more…… Enjoy reading our Real Answers!!
Mr. Hiroshi Nakanishi
Real TIP 2
Director, Techical Service & Commercial Tyre Marketing
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CONTENTS INDUSTRY UPDATE
Mr. Hamed Al-Esry Corporate Road Safety Advisor
What is IVMS? IVMS stands for In-Vehicle Monitoring system.
It is basically an onboard computer in vehi vehicles that measures and records all kinds of information related to the vehicle usage such as speed, distance driven, harsh braking, acceleration rates, seat belt usages, idling/stopping time, etc. This data is then later transferred to a computer or server so that management can analyze the data recorded.
What was the need for introducing IVMS?
IVMS
It was introduced to monitor truck driver’s behaviors on the long roads. Their reactions to road safety, adherence to rules and regulations set by the government as well as PDO.
Monitoring every move! PDO (Petroleum Development Oman is serious a about road safety! On Monday, March 31st U.N. General Assembly session, Ambassador Fuad Al-Hinai, Permanent Representative of the Sultanate of Oman to the United Nations introduced a global resolution to improve Global Road Safety. The resolution, co-sponsored by 94 nations, called for a United Nations ministerial conference on global road safety. 4
Oman, the foremost exploration and production company in the Sultanate) has made it mandatory to install IVMS on all vehicles. Mr. Hamed Al-Esry who is the Corporate Road Safety Advisor at PDO gives us the insight.
What prompted the need? PDO is very serious when it comes to road safety and is committed to reduce the number of traffic accidents, fatalities and injuries.
Oman has alarming road st statistics. Some truck drivers do not realize the seriousness of not following rules and regulations when driving a truck and the significance of the accidents caused. No wonder PDO is serious about road safety! 5
CONTENTS INDUSTRY UPDATE
Which type of IVMS is specified by PDO (With GPS or without GPS)? PDO has made the basic IVMS without the GPS mandatory however; the GPS is an added benefit of the IVMS system. While we do recommend it, we leave the particular specification up to each PDO contractor.
Linked to GPS, IVMS facilitates real Li time monitoring and feedback. The device would carry a GPS receiver as well as a GSM Modem. The modem allows for data to be transmitted to the central computer/server where it is analyzed by the software and reports are generated. On real time basis, the reports can be accessed on a single computer (at each contractor office) or through a web server – the latter allowing multiple users to view the reports anywhere, anytime! The system also allows the vehicle to be tracked and plotted on a digital map.
How does the IVMS help in Truck safety? Our operations cover a large area from the North to
GRADED ROAD
the South of Oman. There are many graded roads and Tarmac roads, some routes cover very long distances. Driving can be dangerous! TARMAC ROAD
Road safety is very crucial to the HSE (Health, S Safety and Environment) division of PDO. PDO concession area is spread across an estimated area of almost 100,000 kms (half of Oman’s total area!) and they have an extensive network of roads: around 24,000 KMS of graded roads (off-roads), 12,000 kms of tracks (minor off-roads) and 8,500 kms of Black Tops (tarmac roads). This area covers a large amount of operating vehicles, PDO’s contractors cover approximately 35,000 vehicles and around 215MILLION kms per year!
It is necessary to somehow control the drivers’ behavior and, for safety, ensure that they adhere to journey management requirements. This includes following the set rules, agreed timings and routes. There is no other way to monitor the drivers when they are on their own, so the system works as a policing tool, governing the day-to-day activities of the drivers while on duty.
What are the responsibilities from the contractor’s side? For the IVMS system to be truly effective, it is important for the contractors to analyze the data available through the system and give feedback to each driver. Each company’s journey manager is responsible for this and it is highly recommended to give feedback to drivers at least once a week.
Prevention is better than cure! Driver’s cannot improve their driving unless they know what they are doing wrong.
Are there any other benefits for the fleets? The system helps reduce fleet maintenance costs (including fuel & tyre costs) because it provides control over speed, harsh acceleration, braking, idle time, etc.
Is IVMS, a mandatory requirement for all fleets? Absolutely! It has been mandatory for all PDO vehicles, contractors and subcontractor’s vehicles for
With GPS, the system allows contractors to locate vehicles in real time thus allowing them to better control schedule and vehicles usage. For instance, contractors can ensure that vehicles are following the approved routes and not using them for other activities.
any contracts signed from 15th Jan 2008 onwards.
Are there any categories of vehicles exempted from this regulation?
Is it a good practice to be followed by fleets regionally and why? It is an excellent practice, if implemented properly. We have seen some great examples within the oil and
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Previously it was agreed to fit IVMS in all high risk vehicles (such as Heavy goods vehicles, buses or any
gas industries and through some of our own contracts. However, proper implementation requires close
vehicle that requires moving around the operation area on a regular basis). But this year it has become
follow ups, monitoring and regular feedback to drivers. IVMS alone does not do anything. It needs a proper
mandatory for all vehicles operating, for any new contracts.
management system from within each company.
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CONTENTS PRODUCT STORY
What’s the difference between “Wear Life” and “Service Life”?
G582
In simple words, “Wear Life” is the life expected under normal operating conditions until the tyre wears out properly, i.e. how long it’s supposed to last.
Enhance Service Life
“SERVICE Life” is the actual life of the tyres, since they are generally changed much before its expected wear life due to irregular wear and other damages.
Is it that hard to improve the service life of a tyre? In order to reduce a fleet’s operating expense related to tyres, one of the biggest challenges is to improve the ‘SERVICE life’ of the tyre. The rubber compound of-course plays an important role, however
At the dawn of the a automotive age, it wasn't uncommon for motorists to carry six spare tires on a long journey. Due to poor design and bumpy roads, the average driver in 1900 chewed up 37.5 tires each year.
While improving se service life, one has to consider that tyres have more than one life. The improvements should be made to not only maximize its original service, but its base structure should remain strong enough for its next lives after it is re-treaded.
It’s always a challenge to improve tyre performance, especially for tyres that operate in certain parts of this region in Middle East and Africa, such as the 1200R24 size. These tyres are subject to one of the most severe operating conditions in the world due to heavy overloading, high speeds and even high ambient temperatures. In addition to that, ANY improvement on one component of the tyre can have a negative effect on another. For example, an attempt to improve the rubber compound’s chip resistance can have a negative impact on the heat resistance
even those little changes in the treads pattern design can dramatically improve the ‘SERVICE life’ of a tyre.
So what has been done to improve the SERVICE life in G582? We focused on improving the SERVICE life in G582 by giving it a larger casing volume, optimizing tread pattern designs, using advanced base compound and introducing tie-bars between the adjacent blocks
What’s the benefit of a larger casing? A larger casing means increased air volume inside the tyre which results in cooler running and better heat resistance.
What does that ultimately do? When the tyre carries heavy loads, more heat is generated inside
5000 kg
5000 kg
the tyre which can cause damages to the internal components leading to tyre failures. With more air volume, the tyre can run cooler since less heat generated inside the tyre and thus the customer can enjoy safer operations, better retreadability and longer tyre life.
How does heat affect tyre life? Larger casing
Normal casing
Rubber wears faster when it is hot!
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CONTENTS PRODUCT STORY
What are the pattern changes that have helped to improve the Service life? G582 has straight shoulder grooves to reduce irregular wear
What kinds of irregular wear do you find on the drive axles?
especially found on the steer and trailers positions. On the drive axles, these block shaped patterns
(Zig Zag grooves)
(G582 with straight shoulder groove)
It seems that as the tyre rolls forw forward, a zig-zag groove is subjected to more stress around the edges (see circled illustration above) which wears them out. Slowly this wear increases and spreads into larger, irregular wear that ultimately reduce the SERVICE life of a tyre. (Irregular wear in general is a very important and bigger topic that we plan to delve into more detail in upcoming issues of Real Answers).
on the tyres are however , very prone to a type of irregular wear referred to as Heel & Toe Wear.
moving direction
Just like a foot, the blocks Ju have a ‘toe’ and a ‘heel’ which function as they do on its human counterpart. The heel touches the ground first and provides support which the toe pushes the foot forward, creating the most friction and is the last part of the foot to leave the ground before taking the step. On tyres, excessive wear occurs on the toe edge of the block and this is because it slips and snaps as it leaves the ground.
Then what is the need for zig-zag grooves in other tyres? They are necessary to provide better traction on wet and off-road surfaces. Basically the traction is like – gripping the road surface and helping to move forward- the zig zag kind of provides biting edges.
Has this been improved in G582?
Does that mean G582 cannot give enough traction off-road?
The centre block pattern on G582 is more rounded. The rounded pattern ensures gradual transition when the block surface area leaves the contact patch. This reduces slippage and snapping of the toe as it leaves the contact patch.
G582 does have blocks in the centre area that provide better traction but it is ultimately a premium long life tyre designed specifically for on-road and mildly off-road usages. It is designed for high heat resistance.
Remember ty tyres are optimized for the conditions they have to be used under! For more off-road usages, we suggest trying other tyres that are designed specifically for offroad such as the M840 and L355.
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How do these blocks in the centre help in traction? Since the G582 is expected to operate on mild off-road surfaces, the centre blocks design helps to provide optimum traction for vehicle’s drive axles. On its soft surfaces the centre block design helps to transfer the torque of the engine to the surface of the road.
5 The G582 blocks are rounded which is optimized between a block and rib design
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BLOCK 10
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CONTENTS PRODUCT STORY
INFO LINE CONTENTS
What is so special about the base compound of G582? Usually, when a base compound is added, the heat resistance is improved but the cut/chip and tear resistance is compromised as a result. So, as the tyre wears out and the base compound slowly gets exposed, it is more prone to cuts and chips thus resulting in earlier removal of tyres.
Are you starving or overfeeding your tyre?
What’s special about the G582 is that Bridgestone has specially developed it to provide more cut/chip resistance as well as the heat resistance. Thus, SERVICE life is extended.
CAP COMPOUND BASE COMPOUND BELT
The base compound is a special rubber co compound (in comparison to the cap compound) that generates less heat. It helps insulate and protect the belt package from the heat. Without the base compound, the heat generated will easily reach the belt package which then weakens the rubber and steel bonding which can then lead to tyre separations (i.e. lower SERVICE life).
What is a tie-bar? Tie-bar is a link between adjacent blocks which causes less movement and higher block stiffness.
Without tie-bar there is more movement of tread blocks
In 1888, John D Dunlop invented the air-filled or ‘pneumatic’ tyres but his were initially made for bicycles. It wasn’t until 1895 that André Michelin tried to use pneumatic tyres on an automobile and EVEN then, it wasn’t a successful attempt! The first pneumatic tyres finally used on an automobile were built by Benjamin Franklin Goodrich in 1896.
By adding a tie-bar the block movements is restricted
Does the block stiffness help to combat irregular wear?
Do you feed more or do you feed less? What do you
By reducing the movement of blocks, the tie-bar helps to reduce the Heel and Toe wear. It also helps
say is the Right amount?
in reducing the block tear that occurs due
To understand this let us
to the scrubbing and dragging of tyres especially when loaded.
examine closely exactly what goes on inside the tyre
That's a lot of small changes with BIG impact! Right on target!
that leads to the problems associated with “More or Less”. Lets start from “why air” in the first place!
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INFO LINE
Why are they called Pneumatic tyres?
So is it the air pressure that carries the load?
The term Pneumatic comes from the Greek word Pneuma which means AIR. Tyres are basically containers
Not exactly! It is the total volume of air in the tyre that carries the load. For eg. In order to carry a given
filled with highly compressed air – hence the term.
Why air and how important is it in tyres?
load, a tyre with a smaller air volume would need higher pressure than that of a bigger tyre (of course load carrying capacity also depends upon other factors such as casing strength etc... but lets not get into that).
In the olden days, the horse carriages used to have wooden tyres and it was a bumpy ride! Air replaces that solid wood, iron or solid rubber. Together with air, the tyre is a vital part of the vehicles suspension system It’s the air that carries the load and prevents those bumps from shaking you up!. It the air that helps to transmit the steering, driving and breaking forces to the ground. Air has the distinct advantage of being able to compensate for different loads. The air in a tyre can be adjusted according to the combination of your vehicle and load carrying capacities. Besides, air is free!!
What do you mean by compressed air? Tyres is a container for air. As you pump in air, more and more air molecules starts getting compressed into this container. Thus the pressure inside the tyre begins to increase and will be higher than what would be in the general environment. Note also that more the air molecules mean more the load carrying capacity of the tyre.
As a tyre rolls, its cross section is constantly cycling between its loaded and unloaded shape, which generates heat.
When you apply load, the tyre is flexing. Does it have any effect on the pressure? No, neither pressure nor volume changes.
95 psi
95 psi
What happens is that the load causes the lower part of the tyre to change shape while the upper part is unchanged. As the tyre rolls, it continually changes to and from that ‘loaded’ and ‘unloaded’ shape. more air molecules
less air molecules
That’s a lot flexing isn’t it? Take the case of a balloon, As Ta you fill in air, it starts to expand. However if you were to put a hard casing around the balloon, it would take in the same amount of air without expanding as it normally does. Be careful though – there is a limit to the amount of air you can put into a casing! Generally a typical truck tyre casing (eg 1200R24 20PR size) contains air pressures up to 125 pounds per square inch (psi). This gives it enough capacity to carry up to 4500 Kgs! (in case of single usage). 14
Yes it is. In fact as the speed increases, this change is happening faster and faster. When you travel at around 90 km/hr each part of the tyre is flexing around 450 times per minute!!
A great deal of en engineering goes to keep flexing in the right area and in the right amounts in tyres.
So the air inside controls this flexing? Exactly! The amount of air determines this flex. Less air means more flexing while more air means less.
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INFO LINE
Does that mean more air is better?
How does low pressure affect my fuel wastage negatively?
Not necessarily. More air pressure means stiffer tyres. You get a rough ride, the tyre becomes more vulnerable
Low air pressure causes excessive flexing which results in higher heat build ups inside the tyre. This
to shock damage, cuts and leads to irregular wear.
wastes fuel energy as heat rather than forward motion, in simpler words; you need a lot more effort to move the tyre which has lower inflation pressure.
Does low air cause problems? So the heat inside the tyre must not be good for the tyres? Low air pressure is a tyre’s worst enemy. It causes premature failures, shortens tyre life, wastes fuel and can be dangerous to drive on.
Of course it is not good! It is one of the biggest problems for tyres! Heat can also shorten the tyre life since rubber wears out faster when it is
How does it cause premature failures?
hot. It also leads to many tyre separations you see on the road sides!
Since the tyre is continually changing shape as it rolls. When there is inadequate air, the changed shapes are much larger. This is made worse with speed and the combination of both results in faster tyre wear, fatigue to the tyre cords and cord breakage.
Part of the manufacturing p process involves different components and raw materials of the tyre being bonded together. Excessive heat causes the bonds between these tyre components to break which leads to tyre separations.
So the air pressure needs to be “just right”? Yes! Not too much and not too little! The right amount of air pressure is required depending upon the
How does it become dangerous to drive? A tyre with low air pressure has a sloppy road feel and can skid on
vehicle’s load and operating conditions. Please do not forget it’s extremely important to periodically Low or high pressure can change the tyre foot print (contact area between tyre and road surface) and the (c pressure per square inch it exerts on the road surface. Both these can have a negative impact on the traction and control of the vehicle.
Footprint or contact patch at different pressures
the turns!!
maintain your tyre pressures!
The air in your tyre is constantly leaking. It is a little easier to un understand when you compare it to a balloon. Take a regular balloon, blow it up to maximum capacity and leave it aside. Day by day, you will notice that the balloon gets smaller and smaller! This basically means that the air you have blown and sealed into the balloon leaks through the rubber. Of course, tyres are much more complicated than balloons and have much more air retention but the point is that the air in them leaks through the rubber naturally. In addition to that, tyres face leakages from defective rims, valves, small punctures, etc. Basically, your tyre can lose air!
35 psi
30 psi The footprint of the tyre gets longer!
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26 psi
2 days
Therefore, for your own safety, check your tyre air pressure once a week and before long trips to ensure it is at the right level.
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PERSONAL DIARY CONTENTS
Roy J. Carver (1909-1981) of Muscatine, Iowa was educated as an engineer and had the drive of a classic entrepreneur. He had a passion for quality in all that he undertook.
Roy Carver The legend that revolutionized the industry
Carver wasn’t in the retreading or tyre business.. Bandag as a matter of fact, was the third company started by Mr. Carver! In the late 1930’s and 1940s, he was an inventor and seller of industrial pumps, as the owner of Carver Pump Company. During the Depression, he used to buy broken pumps and using replacement parts, rebuild them to good working order. The knowledge gained from working on broken pumps and why they failed helped him build superior high quality pumps. In fact his pumps were very popular in Europe and had a reputation for unparalleled performance.
The name c comes from Nowak's initials (BAN); D is for Darmstadt and AG is German for incorporated.
In the 1950’s, he launched Carver Foundry products to supply the molds for his pump company. On his business trip to Germany to promote pump sales,
he noticed the tyres on one car had been retreaded in a way that he’d never seen before. Not only did the retread cover only the
Bandag is one of the greatest business success stories of the second half of the twentieth century. From its founding in 1957, Bandag revolutionized the tyre retreading industry by introducing a cold “pre-cured” process designed to produce durable retreads from used truck tyre casings.
The company's worldwide success was made possible
tread area of the tyre but they were ‘pre-cured’ to improve durability. The inventor of this new system was Bernard Anton Nowak of Darmstadt. BANDAG , Incorporated commenced in the United States on December 20, 1957. The Bandag name combined Nowak’s initials (BAN) with “D” for his hometown (Darmstadt) and “AG” for the German abbreviation for “Incorporated”. Carver also secured North American rights to Nowak’s retread process. Carver revolutionized the Retread Industry
Before Bandag, the dealers operated independently and there were no warranties, no brand names, trainings etc. Even the vendors were different; buffing machines came from one manufacturer, hotcure molds from another and rubber came from still another. For every pattern/size, the dealer needed a different hot-cure MOLD, obviously it was impossible to have a mold for each and every size. Pre-cured Tread: The Bandag’s system uses pre-cured treads that are bonded to the casing. The retreader had to simply cut the pre-cured tread to the size required. This eliminated the need to keep the extensive molds on hand for the different sizes that were required.
thanks to the vision of one manRoy J. Carver.
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Since there was no mold required, a metal band was used to apply pressure to the tread and casing during the curing process. (In 1963, Carver developed the idea of rubber curing envelope which solved many curing problems and eliminated heavy and expensive metal curing bands) 19
PERSONAL DIARY CONTENTS
Carver’s concept was groundbreaking. He sold franchisee agreement to tyre dealers so that they could manufacture and sell Bandag retreads. The Retreader could get all what they needed under one roof. They obtained pre-cured tread, equipment, training, sales / technical assistance and advertising support.
CONTENTS EXPERTS SPEAK
Valve caps –
It was not an easy task
Big deal??
Founded in 1957, Bandag had five employees and one manufacturing facility to produce and sell retreading materials to their one and only franchised, independent tire dealership.
In order to drive Bandag forward, Carver nearly lost all money from his pump company. It is said that at one time, he was basically insolvent. Carver flew to dealers and sold stock to eight of them, raising the much needed $50,000 that weekend. Today Bandag, Incorporated is the world leader in truck tire retreading with almost 1,000 franchisees in nearly 100 different countries. From a retread supplier, today Bandag provides programs, services, information and products that can cover vehicle centric needs from trailer inspections to tire management solutions. The Matchless Enterprenour Mr. Carver had a passion for quality in everything, He had a lifelong interest in aviation and world travel and spoke five languages fluently. He was a very generous man and he was widely recognized in business, community and activities in support of higher education.
Bandag Milestone during the time of Roy Carver (1957-1981)
1957 : BANDAG started. 1961 : The first press is installed. Tread is pressed in 30-foot lengths, 6 pieces at
What’s the big deal anyway?! We are talking about the most neglected part of the vehicle – The little plastic valve cap on the tyre! This little thing is however one of the most crucial part of the tyre: it’s the final seal that keeps air inside the tyre. No doubt it needs to be maintained, however that’s easier said than done. Is it so difficult? Is there a solution? Let’s find out the Real Answer!
valve cap
valve core valve stem
a time. The first designs were Highway, Cross Bar and HiSpeed. 1963 : Roy Carver develops the idea of a rubber curing envelope. 1968 : Bandag is offered to public at $12 per share. 1972 : The company is listed on New York stock exchange. 1974 : For the fist time in company history, Bandag is listed on the 1974 Fortune
rubber base
magazine's list of top 1000 U.S industrial corporations. 1978 : Bandag has 859 dealerships and is franchised in 51 countries. 1979 : Bandag introduces the NDI (Non–Destructive Inspection), Tire Casing Analyzer which uses ultrasonic sound waves to detect hidden flaws in tire casings. 1981 : Roy J. Carver dies in Marbella, Spain, after suffering a sudden heart attack. Martin G. Carver is named Chairman of the Board and CEO.
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CONTENTS EXPERTS SPEAK
What does a tyre valve cap do?
Then why are valve caps so neglected?
To answer that you need to look into the three components of a valve assmebly: Valve stem, valve
It’s easy to recommend diligent care for your caps but it is much easier said than done.
core and valve cap. You inflate and deflate the tyre through the valve stem. The valve core controls the air flow. It seals the air inside the tyre and it opens up when you check pressure or fill pressure.
In reality, tyre technicians are usually struggling with your
Finally, the valve cap is the secondary air seal and it also acts as a seal to prevent dirt from getting
tyre during the day in scorching heat! It is easy to drop
into Valve Core.
a valve cap when struggling to remove it, especially in the summer heat when the rim and valve stem heat up. Technicians usually need to wear gloves to prevent
So how does that make valve caps the final seal?
burns and this adds to the awkwardness of handling a small valve cap. On top of all that, it’s easy to lose a cap
The spring and rubber seal in the valve core prevent air from escaping from the tyre. In order to
while fumbling to fit it back onto the stem – imagine
inflate your tyre or check its pressure, you press open the seal using a guage. The trouble is, this seal
looking around the vehicle for a small valve cap under
becomes vulnerable to mechanical problems when dirt is let in. In such a case, the valve cap acts as
the sweltering sun!
a secondary seal.
It must be even harder when working on a truck’s tyres in the heat…? Water and dirt disrupt the mechanism of the seal which casuses air leakage.
Yes! So consider the time it takes for your tyre technician to remove the valve cap, fill the tyre with air and then screw it back on – for all the tyres on your truck!!! Not to mention the inconvenience of dropping a cap and many times
Always en ensure to keep plenty of spare valve caps!
someone else has screwed the cap on before and over-tightened it making it
How does dirt cause leakage?
even more difficult to remove.
It gets into the seals, holding the valve partially open and depending on the amount of dirt/moisture, air is let out quickly or slowly. Obviously, the more the dirt, the more leakage.
Is it worth the trouble then? Yes, every minute of it. Especially considering the possible consequences of low tyre pressure. You can avoid tyre damages, get longer tyre life, have better fuel consumption and more re-treadings!
So valve caps are necessary to prevent air leaks? Absolutely necessary! It prevents the dirt from getting inside and acts as a secondary air seal too!
Air leakage in your va valve leads to all of the tyre damages caused by low air pressure and underinflation. Be sure your valve caps are intact!
Is there a better solution when it’s so inconvenient? We could recommend using good quality metal flow through type valve cap with a good heat-resistant internal rubber seal. The internal rubber seal is important to make sure that the cap actually closes off the valve stem completely, keeping the air inside.
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EXPERTS SPEAK
CONTENTS PURE TECH
What about plastic caps?
Inflation pressure
Metals caps are the best solution since metal won’t crack or split as a result of exposure to the sun.
What do you mean by the flow through type valve cap?
- Demystified!
The valve cap contains an internal check valve, thus you can fill air through the valve cap and air flows though this internal valve and then through the valve stem into the tyre.
But how does it ensure the safety of the valve core in the valve stem? The cap has a ring-like seal that seals it to the valve stem (like a conventional valve cap). Then inside the cap is a second seal that keeps the valve inside the cap closed-until you apply an air hose or gauge.
If the core inside the stem should fail, the pressure of air trying to escape actually causes the valve cap seal to seal more tightly providing additional protection.
Is it wise to invest in a metal flow through type valves? Well as the saying goes, don’t be penny-wise pound-foolish. Treat your valve hardware with the same importance as your new tyres. Don’t risk the health of your expensive tyres for a few fils saved on your valve caps.
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PURE TECH
What is Pressure?
So different tyre sizes with same ply rating can carry the same tyre load?
Pressure is defined as Force per unit Area.
No. The ply rating applies to the same size. When the sizes vary, even the same ply ratings show different load
Pressure = Force / Area
carrying capacity. For eg: as per ETRTO (European Tyre and Rim Technical Organization) Standards:
How does pressure work inside tyres? The air exerts pressure inside a tyre through the action of the air molecules colliding with the inner-liner. By its collisions with the inner-liner, the molecules exert an outward pressure. Now there are two ways to increase the pressure inside the tyre: a) One is to raise the temperature (hotter the molecules, faster they move) b) The other way is to put more air. More air means
Size 1200R24 18PR 1200R20 18PR
Load Index (Single tyre) 156 154
Pressure (KPA) 775 850
Load Cap - Single (Kg) 4000 3750
How do you measure Inflation Pressure? • • • •
1 Atmospheric pressure = 1.013 bar = 14.7 psi = 1.033 kg/cm² 1 bar = 100 Kpa = 14.5 psi = 1.02 kg/cm² 1 psi = 6.9 Kpa = 0.069 bar = 0.07 kg/cm² 1 Kpa = 0.01 bar = 0.145 psi = 0.0102 kg/cm²
more molecules and more molecules means more collisions and greater pressure is exerted on the sides of the tyres (or container)
What is Atmospheric pressure?
Take the case of a balloon. Fill air into the balloon. The air inside
Atmospheric pressure is
this balloon pushes outward in all directions. That push is called
defined as the force per unit
pressure. The pressure makes the rubber stretch, causing the
area exerted against a surface
balloon to expand.
50
standard pressurea sea level (1,013.25 mb)
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by the weight of the air
stratosphere (13-50 km)
molecules above that surface.
Yes it will increase the pressure. However it’s not the amount of stretch (incase of balloon), it’s the push inside the egg. Since the area is kept constant, the more air molecules you fill in, the more the pressure increases.
And what about a tyre? Is it an egg or a balloon? It’s a combination of both egg and the balloon. The rubber can stretch to a certain point. At the same time, the tyre consists of plies (casing and belts) which give a certain shape to the tyre when the air is filled in. The casings gives strength to the tyre to carry more air.
What is Ply Rating? Even though it sounds very technical, Ply Rating is quite simple to understand. The Ply Rating or Load Range of tyre indicates the maximum inflation pressure and the corresponding maximum load for which the tyre is
The atmosphere is about 50 miles "deep," and at sea level it exerts 14.7 pounds per square inch (psi). Our bodies think 14.7 psi is completely normal. This 14.7 psi is the ATMOSPHERIC pressure. 1 atm = 14.7 psi = 1.013 bars
altitude (km)
30
Suppose this balloon is an egg shell and you push more air into it? Will it increase the pressure?
radiosonde baloons (18-30 km)
20 Boeing 747 cirrus clouds (10-13 km)
10
tropopause (10-13 km)
Mt. Everest cumulus clouds (1-2 km)
0
200
troposphere (0-10 km)
altostratus clouds (4-5 km)
400
600
800
1,000
1,200
pressure (mb)
So does the pressure inside the tyre include atmospheric pressure? Yes we call the total pressure as absolute pressure. However the measure is the Gauge pressure. The pressure gauge set at 0 has actually an absolute pressure of 14.7 psi.
So if a tyre shows 30 psi, on a pressure gauge, it means that the absolute pressure is 30 + 14.7 = 44 psi?
designed. It is considered a relative index of the casing strength. Note that it has no relations whatsoever to the number of plies in the tyre. 26
Absolutely right! But in the tyre industry we only measure the gauge pressure as reference. 27
INTERESTING FACTS
Vulcan the true Iron Man! The word Vulcanization is originally derived from Vulcan. Vulcan is the roman God of fire, believed to have made weapons and armor for all the gods. The vulcan sculpture was, and still is the world's largest cast iron statue. Vulcanization is an invention that has widely aided the use of rubber and has greately helped industries such as the automobile industry. It is the process by which rubber hardens and gives it qualities of strength and elasticity (Elasticity is defined as the possibility to return to the original shape after a deformation), i.e, since natural rubber by itself is sticky and can easily deform when warm and is brittle when cold, it undergoes vulcanization. During the process molecular sulphur is mixed with natural rubber and heated. This causes the sulphur cross-links to form between the rubber molecules, giving it the essential qualities. The tyre and autombile industry could not have flourished the way it is today without the Vulcanization process. Thanks Vulcan!
The 56-foot statue of Vulcan in Birmingham, Alabama, is the largest cast-iron statue in the world.