Failure to understand the basic requirements of a tyre extends from drivers and operators to the very people involved in road safety and vehicle regulation. When they are asked how can the computer controlling an autonomous vehicle (AV) know that it has a deflating tyre if tyre pressure monitoring is not fitted, they usually hide under their desks?
Isn’t it a human trait that we like to make things more complicated than they really are? When we look at a tyre, some of us see amazing technology, while others just see a round black rubber doughnut under our cars. Some don’t even see the tyres! Many people do not understand the very special mechanism that a tyre is. There are those who motor race to those who ride in pelotons, all with an understanding of what a tyre provides to them.
However, do we overlook the basic function of a tyre when we admire the tread pattern or consider the ride qualities? A tyre provides the necessary functions for a modern vehicle to perform as we expect it to, be it a wheelbarrow or a giant haul truck weighing 600 tonnes. Braking, steering and traction are all the common themes of tyre functions but these are advanced functions.
Why Tyres Fail
A tyre is a receptacle for the chosen inflation medium (or air), just as an air receiver or even a balloon is. The tyre retains the air within its structure, known as the car tyre pressure. The prime purpose of a tyre is to support the applied loads, yes plural. The mass that a tyre supports is one load, the tractive forces are the next major load a tyre has to deal with. Without the inflation medium, the tyre cannot perform its functions.
We look at data from many different applications. Be it mining or transport, we observe a huge lack of care and attention when it comes to tyre safety. It seems people are either not aware or just don’t care. But, for one reason or another, people who should know better choose to ignore the basic requirements of their tyres and this endangers all road users. When a tyre has failed in a catastrophic manner with quite possibly property damage and/or personal injury, TyreSafe Australia is called upon to determine the reasons underlying the failure.
Why did the tyre fail like this? Well, there are several plausible reasons available; but more often than not, there has been a lack of attention to the car tyre pressure. This failure to understand what a tyre need isn’t just restricted to drivers or operators. This extends all the way to the very people involved in road safety and vehicle regulation.
Why Bury Your Heads?
We have examined the legislation around vehicles in several different jurisdictions, with special attention to Australia. In some jurisdictions, there are design rules for passenger cars, rules that require a tyre placard to be located on the car. It may be on the door, the B pillar or even the glovebox and certainly in the owner’s manual. It calls for a minimum tyre inflation pressure and usually details the car tyre options available for the vehicle. Other jurisdictions call for tyre pressure monitoring (TPMS) as a standard feature.
For heavy vehicles, most jurisdictions do not require tyres to be inflated. Yes, you read that correctly. In many jurisdictions, tyres on trucks and trailers are not required to be inflated by regulation or legislation.
When I bring this to the attention of the regulators, the usual reaction is to make excuses or suggest that it is common sense that tyres have to be inflated. So when I raise the topic of autonomous vehicles (AV) and ask these same regulators how does the computer controlling an AV know that it has a deflating tyre if tyre pressure monitoring is not fitted, they usually bury their heads in the sand. Even large manufacturers of AVs have not included tyre pressure monitoring as standard equipment on their computer controlled vehicles. The Ostrich syndrome?
My thinking is that it is not until the computer determines that the vehicle is not travelling in a straight line (called dog tracking or crabbing) that the analytics start to run into issues controlling the vehicle.
A human will compensate and make subtle corrections to the steering in order to keep the vehicle heading in the general direction. A computer, well they are clever, but without the right information, the first law of computing applies, GIGO.
It is a basic premise of a tyre that the appropriate volume of air is required to be installed. It takes little imagination to understand what would happen if we were to play football or basketball with a semi-deflated ball. Let’s get down to basics – how would a party balloon look if it was under-inflated?
Tyre Pressures Neglected
I am continually stunned when educated people who form up the regulations for transport vehicles neglect to include tyre pressures as a requirement. A procedure was published not long ago for Roller Brake Testing. This procedure outlined how a test would be conducted on a truck to determine if the brakes were capable of stopping the truck at a reasonable distance. There was great detail about the truck’s air brake systems, great detail about how the truck should be set up and the methods involved. Within the vehicle, the set-up requirement was a statement “tyres should be inflated.” When I suggested that a tyre could be “inflated” at 20 psi when the actual working pressure of the tyre was 100 or 120 psi, there was only a gasp, and the sound of heads disappearing into the sand, again.
Why do intelligent people continually ASSuME that tyres somehow operate without air? How does an engine operate without lubricating oil? How does a human operate without blood? We all know the answers to the last two questions; but when it comes to putting air into a tyre, everyone ASSuMEs. So when the tyre has gone flat and the vehicle is stopped on the side of the road, who looks like the ASS?
There is a wealth of data available which evidences the economic and safety benefits of appropriately inflated tyres. It seems that people wish to put the cart before the horse and install complicated electronic systems for electronic vehicle stability, electronic braking even autonomous control yet ASSuME the tyres will be “ok”. Why are they ignoring the basic requirements of the humble tyre?
Tyres are the only thing between your vehicle and the road, the small patches of rubber that you control. Look after your tyres so when you call upon them to look after you they will be ready and able to do so.
I encourage all tyre manufacturers, heads of companies who use tyres for their daily business, drivers of passenger cars, drivers of heavy vehicles to directly ask their elected representatives and the bureaucrats who formulate the regulations pertaining to road safety, why are the tyres on our heavy vehicles not required to be inflated? If they don’t make sense then ask again, and again!