There are very few fleets where tyres are under control. And don't think that an outsource supplier does it better. Delegating tyre responsibilities to a service provider does not remove the need to frequently audit their standards and procedures. You can get someone else to do the work but in the final analysis, safety and quality cannot be delegated - especially given that there are some service providers in the tyre business who are an industry disgrace. It's the same wherever you go for any service - some are good, some great, some horrendous. Too often tyre failure is blamed on the product, expressed as "die band het gebars!" From cradle to grave, a tyre's life is in the hands of the way it's managed, either by an individual or by a company. Here Dave Scott, our technical correspondent, highlights 28 items to be aware of when it comes to tyre mismanagement. Some are worn to the canvas from repetition while others may come as a surprise.
1) Ex-plant drive-away pressures not followed up
Chassis/cab units are driven by road from assembly lines to body builders and dealers. An empty chassis/cab has its tyres pumped to 50% of maximum pressure otherwise the tyre will be damaged on the road. Because the truck is new - and providing body fitting is not a lengthy period - the incorrect assumption is that the tyres are correctly inflated for operation. No checks are made and the truck goes into service at 50% of the correct inflation pressure. It all points to a faulty pre-delivery service.
2) Flawed new vehicle delivery - inadequate PD's
Just as truck tyres are under-inflated for new chassis/cabs, so too are passenger and LCV units over-inflated to ride securely when strapped-down on a car carrier. Many dealers do not have compressors that can reach the right truck tyre pressures - up to 800kPa. The fact that a new vehicle dealer will conduct a pre-delivery service and then take the truck to a nearby filling station to check the tyres does not ring true.
3) Lack of written tyre policies
Lowest tyre cost is the result of discipline and this can only be applied with reference to a policy/procedure document. Too many fleets operate without a tyre policy - things just 'happen'. If your company does not have a written policy, get SABS ARP007 Edition 2 1992 (As amended 1992). It's a good basis as a company policy for the care, maintenance and use of tyres and rims
4) When tyres are not classed as 'safety critical items'
When a safety critical component fails, it should be treated as a 'case of rabies'. Is the failure the tip of an epidemic? Instil the fact that tyres are 'safety critical' and that operational failure must have a sound reason and be recorded. Tyre failures must not be glossed over as 'operating problems' for this can consume the business.
5) Scrap tyre analysis - no procedures and records
When a tyre is permanently withdrawn from service, it's got to be a formal procedure. The scrap analysis is an asset death certificate - it details why this asset is scrapped and then the beading is cut with an angle-grinder to ensure the carcass doesn't appear again in the fleet, or on the road on someone else's truck. It's more important to control incidents to bring down costs than prices on invoices.
6) Graft, bribery and missing ethical values
Tyres are negotiable assets and an easy target for corruption, theft and fraud. After fuel, tyres are the one area of business that needs close scrutiny - trust no one!
7) Tyres are tyres - any make will do at the lowest price
It's impossible to set standards and track wear when a fleet rolls on a vast array of different tyre brands. Not all tyres are made equal and this is reflected in the price and service. Quality comparisons get lost in brand confusion that makes tyre databases meaningless. When there are too many brands, purchasing power is also eroded.
8) Compressed air equipment not equipped with air driers
Air compression equipment attracts condensation. That's why modern trucks are equipped with air driers to keep moisture out of the air brake system. Compressed air lines should be moisture and debris free but all too often, the air compressor and pressure vessels are forgotten equipment. Any pressure vessel needs annual certification? Is this being done?
9) Shifting load centres at lower GVMs
A truck may be carrying 50% of rated maximum load but the position of the load on the deck is critical. Very often the front axle tyres are overloaded due to a forward-shift in load centre caused by rear unloading.
10) Under-rated compressors and inadequate air pressure
Under-inflation in fleet tyres sometimes occurs because tyre service equipment can't reach the required pressure. This is never reported - it's just the way things are. Often tyre pressure gauges have never been calibrated and the faulty gauges combine with inadequate pressure to complete a perilous illusion.
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Whacking
a tyre with
a baton may detect a flat tyre in comparison to one at full
pressure – but the sound of a tyre that is not correctly
pressured will not be picked up. There’s no substitute for
an accurate tyre pressure gauge. |
11) Air pressure leads and re-fuelling located at different points
I have seen operations where a truck must be moved twice around the yard to check tyres and re-fuel. Laziness creeps in and moving twice is time-consuming and too much effort. Fuel fills will happen but tyre pressure checks may not in such a situation. When a vehicle is checked, it should be a scientific, recorded pit-stop operation and not the sloppy event that happens so often.
12) Untrained drivers do not understand tyres
If tyres are a driver's responsibility, then write this into the job description. Train them, not just in procedures but in the serious reasons why they must understand tyres. Why are valve-caps necessary? Why must hot tyres not be bled? What is an impact fracture? This also, of course, applies to owner-drivers who really should know better. Pathetic driver check lists that supervisors ignore only compound the problem. It's essential that tyre pressure ratings are clearly visible somewhere for ease of reference.
13) Total absence of measuring equipment
Tread depth gauges, T-pieces, pressure gauges and torque wrenches are missing or not calibrated. If you can't measure it, you cannot manage it.
 |
Many
fleets
measure wear in terms
of mm tread wear per 1000km. Tread depth is critical to
being legal on the road – refer to RTA Regulation
212(j)(ii) |
14) Lack of a passion to measure tyres
Transport operations supervisors should carry a high-quality pressure gauge and execute sample spot-checks. The culture must be passionate about measuring and recording tyre pressure. 15) Lack of tyre terminology education
The FleetWatch A-Z of Road Transport Volume 3 Revised carries 37 definitions that supervisors and operating staff must use with common understanding. Don't chat to each other inside a tyre Tower of Babel.
16) Pump jockeys bleed hot tyres and lose valve caps
Filling station pump jockeys check hot tyres when motorists pull in for re-fills on the road. These tyres can be as much as 20% up on cold pressure and get bled to reduce pressure to the detriment of the tyre and motorist. This is where valve caps also go missing.
17) 60% rear overhang becomes a standard
The RTA Regulations permit a 60% of wheelbase rear overhang. This is not an ideal standard for mass haulage as the rear axles are easily overloaded due to a load centre that is too close to the rear axle(s). Where payloads switch from volume to mass, this causes rear tyre wear without prior warning.
18) The value of a valve cap not understood
A humble valve cap can retain pressure if the tyre valve is faulty. Its main purpose is to prevent road muck from entering and jamming the valve. Lost valve caps are a major contributor to run-flats.
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Where’s
the cap?
A humble valve cap such as fitted to the valve pictured here
can retain pressure if the tyre valve is faulty. Its main
purpose is to prevent road muck from entering and jamming
the valve. Lost valve caps are a major contributor to
run-flats. |
19) No understanding of GVM - mass versus volume
Overloading is a prime tyre failure problem. Every product has a specific gravity ratio and training against overloading is a process that everyone must understand.
20) Max height/max width = max roll and no stability
It's visible everywhere. Distribution vehicles are fitted with maximum-dimension box van bodies that never get filled to capacity. The effect of an over-dimensioned body is excessive tyre wear due to vehicle sway and stability on the road
21) Trailer load-sensing valves not operational
This simply means wheel lock up every time and tyre flat-spots. Many load-sensing devices simply do not work.
22) General neglect of trailer running gear
Worn trailer axle bushes and suspension mountings cause the axle unit to move around with a massive impact on tyre wear.
23) Inadequate distribution of braking forces
Mismatched trailer boosters and incorrectly set booster control rods result in unequal braking forces being transmitted to the road through tyres.
24) No extension valves - inner dual wrong position
This is a most prevalent problem - the inner tyre of a dual set cannot be pressured or checked because an extension valve is not fitted. An under-pressured tyre on a dual set wears more rapidly as it runs at a different and slower speed to the correctly pressured tyre that has a larger diameter.
25) No understanding of traction ratios inside GCM
Under-loaded drive axles cause tyre spin and slip when maximum engine torque is applied. Loading a 3-axle trailer unit to maximum and running a 4 X 2 truck tractor drive axle empty is cause for major tyre wear.
26) More tyre damage empty than loaded
An empty truck on the return leg and running on maximum pressure can cause more damage to tyres than when loaded. A combination of speed, route and road surface will impact on tyres at maximum pressure without load.
 |
|
An
empty truck
on a return leg running on maximum pressure can cause more
damage to tyres than when loaded. |
27) Maximum pressure rules - no load/route study
Maximum pressure is not always ideal. There is a recommended correct pressure that results from route and load studies.
28) Poor speed control - exceeding speed rating
All tyres have a recommended maximum speed rating. Exceed this continuously and dangerous failures will occur.
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|
The
value of
tyres on just this tri-axle unit is around R30 000 –
"I cannot understand why tyres get abused the way they
do when one looks at the total safety and cost implications
of a 7-axle combination on the road", says Marcus Haw,
Manager Field Engineering Division at Bridgestone
Firestone. |
Tyre prices follow the fuel price - watch this roll upwards. Taking charge of these 28 items will ensure that a business does not haemorrhage from tyre expenses. More importantly, there are massive court claims already set in legal precedent that resulted from tyre 'failure'. Tyre safety is everyone's concern, not just a driver's problem. Reference & Acknowledgements
Bridgestone Firestone booklet - Reduce irregular wear...the S.M.A.R.T. Way!
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