‘Oil – water – tyres’ is the mantra of pump jockeys at a filling station. What they are referring to of course are tyre pressures which is the pressure reading of a tyre at ambient temperature and varies greatly between hot and cold weather.
Climate change that results in baking-hot road-surface conditions is the enemy of rubber and truck/bakkie tyres – especially damaging to recap
tyres on truck drive axles and trailer tyres.
Tyre pressures increase by as much as 20%* running fully laden on a hot summer day – the danger is that drivers bleed off this increase in
pressure thinking that they are doing the right thing.
This results in tyres flexing excessively due to being under-pressured – a combination of road heat and excessive flexing can result in tyre failure.
It’s a fleet and tyre management issue across the board – truck, bakkie or car.
Aside from tyre failure is the problem of increased wear. Under-inflation by as much as 20% shortens tyre life and increases operating costs. When running long-haul, the simple test is to execute the ‘touch-test’. All tyres will be warm to the touch in operating conditions. Any tyre that is excessively hot to touch and ‘out-of-synch’ with the others on the vehicle is a reason for concern – this is the one that is losing pressure. A vehicle parked for a few hours in the morning sun will show a different temperature for the ‘sunny-side’ tyres when compared to tyres in the
‘shadow-side’.
What gets overlooked is that recommended tyre pressures are cold- rated – that is when an accurate kPa check should be carried out and
not when a tyre is hot from hard work.
*Pressures will increase up to 20% in operational conditions – SABS publication ARP007 3.2.3
