At this stage of Tyre academy you have now acquired a huge amount of information and are well on your way to becoming a program graduate. Nearly all of the factors which you have encountered so far will contribute in some degree to your own safety. This module will allow you to see just how much safer you may now be given your new understanding.
As the only contact point with the road, the tyre plays an essential role in safety
It has to provide sufficient grip when turning and braking on both dry and wet roads. Grip is ensured by the contact area between the tyre and the road, on a tiny patch no bigger than your hand.
There are three main enemies of the tyre: physical, environmental and 'human factors'. Common enemies include: inflation pressure, road hazards, tread depth, weather conditions, lack of maintenance, load, speed, and so on.
Between the rigid road and the plastic elastic rubber, two factors come into play: molecular adhesion and indentation.
On dry ground, rubber has a tendency to bond, accounting for 75% of grip.
Its malleability helps it to distort the impact of road surface irregularities. This is indentation and accounts for 25% of grip.
On wet roads, water molecules neutralize the grip effect of tyres, leading to increased braking distances and, in extreme cases, Aquaplaning.
Firstly, tyres are designed to form a rounded footprint to drain the water away.
Secondly, grooves between the tread blocks form channels in which the water can be temporarily stored or else drained away to the rear and sides of the tyre.
See below how tyre pressures can affect safety
Endurance
Driving on under-inflated tyres reduces their endurance capabilities, leading to deterioration that could even result in a rapid deflation.
7 psi (0.5 bar) or more under inflated = is potentially dangerous
Road Holding
With under- inflated tyres, the vehicle's steering is less precise.
If a bend can be taken at 62 mph (100 km/h) at a tyre pressure of 29 psi (2.0 bar), this speed drops to 54 mph (87 km/h) at 15 psi (1.0 bar), or about 8 mph (13 km/h) less.
Lower pressures = Lower tyre potential performance
If tyre pressures are 30% below the recommended pressure there is a sharp increase in the risk of aquaplaning.
Lower pressures = higher risk of aquaplaning
Braking
In addition, tests show that braking distances from 56 mph (90 km/h) to 43 mph (70 km/h) are 40 metres at 29 psi (2.0 bar) but 45 metres at 15 psi (1.0 bar), that's 5m longer.
Tyres under inflated by 15 psi (1 bar) have increased rolling resistance leading to around 6% greater fuel consumption.
Driving at Speed
Driving at high speeds has a greater chance of causing tyre damage than at low speeds. If contact is made with a road hazard, it has a greater chance of causing tyre damage.
If you see any damage to a tyre or wheel, replace it with your spare tyre at once, and then have it checked by a tyre specialist.
Overloading
To ensure that your tyres are not overloaded, read the load index of your tyres, which is found on the tyre sidewall.
Do not exceed the load capacity relative to this load index.
Tyres that are loaded beyond their maximum loads can build up excessive heat that may result in sudden tyre destruction.
Also follow your manufacturer's loading recommendations. Do not exceed the maximum axle load rating for any axle on your vehicle.
What’s next?
Well done for completing level 2. It’s time to test your knowledge again. Click on the quiz link below and let’s see how well you are doing.
We’ll analyse your results and email them to you in a few days.
Once you’ve completed the level 2 quiz, and when you are ready, move on to level 3.
