Tyres: Under pressure

Incorrect tyre pressures cost money and could cost lives.

Simply travel a year on tyres that are under-inflated by 20% and the additional rolling resistance will cause your fuel bill to rise by 2%.

It will also impact on tyre life (see table, below), according to Michelin-owned fast-fit network ATS Euromaster.

There are three key areas to consider: over-inflation, under-inflation and differing pressure for front and rear tyres.

• Low pressure for the front tyres encourages understeer; low pressure for the rear tyres encourages oversteer.
• Over-inflated tyres wear the tyre in the centre and have a smaller contact patch with the road. The tyres also become more susceptible to shock and impact damage.
• Under-inflated tyres get worn excessively on the outer edge. It also causes excess heat to be generated, described by ATS as “the biggest enemy of the tyre” which can lead to tyre blow-outs. The contact patch is less firmly braced because the tyre can flex away from the road.

The implications of incorrect tyre pressures can be far more deadly on a wet road. The speed at which aquaplaning could occur falls by a significant margin.

So what are your options to address the tyre issue? Tyre pressure monitoring systems can cost £100-200 and might be worth considering if the problem on your fleet is particularly widespread.

However, education of drivers and regular tyre checks (monitored by spot checks) can be just as effective – and far cheaper.

ATS recommends a fortnightly tyre check which can be audited. It also suggests fleets should provide drivers with pressure gauges.