How many times have your drivers been stranded at the roadside with a puncture?

Not that many, perhaps.

But according to the RAC, the number of puncture call-outs is on the rise.

In 2002, its patrols responded to 160,908 incidents – by 2007 this had risen to 230,196. The AA says it attended 330,000 tyre-related call-outs last year.

Punctures present two obvious dangers for drivers – the risk of losing control of the vehicle and the risk of being stranded in a dangerous location, such as the side of a motorway or in a remote area.

Aside from stipulating that drivers check tyres weekly, fleet managers should make it clear what to do in the event of a puncture.

Most fleet operators choose to state in their health and safety policy that a breakdown service must be called to repair a puncture.

Another method, which could get a driver on the move again more quickly, is the provision of a sealant kit.

“It serves a purpose for lots of types of puncture,” says James Bailey, corporate communications manager at Goodyear, though Peter Robb, brand manager at Continental, points out that it cannot fix sidewall damage and is only a temporary repair.

Risk management experts champion a third solution for punctures – fitting vehicles with run-flat tyres.

Unlike conventional tyres, when a run-flat tyre has a puncture it retains its basic shape.

“They have more robust sidewalls, reinforced with a special rubber compound, to carry the weight of the vehicle at low, or even zero, pressure,” explains Steve Dolby, product marketing manager at Michelin.

Safety elements

The fact that the tyre keeps its shape when it loses pressure allows the driver to maintain control of the vehicle and safely bring it to a halt.

This could be life-saving in the event of a tyre blow-out.

Tim Bowden, head of operations at Hitachi Capital Vehicle Solutions, suggests it may take an experience like a blow-out to make drivers really appreciate having run-flats fitted.

Another safety element is that the driver is alerted to any loss in tyre pressure because the tyres work in conjunction with a tyre pressure monitoring system.

As James Bailey points out, blow-outs are usually caused by the tyre being at a low pressure over a long period of time.

It is clearly an advantage to have an early warning about a drop in pressure.

Some manufacturers, such as Bridgestone, suggest that run-flats eliminate the possibility of high-speed blow-outs.

One of the main benefits of run-flat tyres is that they allow motorists to continue driving – albeit at a reduced speed and for a limited distance.

This means they can make it to a nearby garage or drive home safely rather than waiting at the roadside.

Graham Rixon, operations director at LeasePlan, says: “Run-flat tyres help firms with their duty-of-care obligation.”

The benefits were recently experienced at Fleet News as senior reporter Gareth Roberts was able to drive home when the BMW 320d he was testing had a puncture (see story below).

He admits, however, that he was not entirely happy with the car’s handling when driving with a puncture.

In response, BMW states that handling will be impaired, compared to a fully-inflated tyre, but it is perfectly safe to drive a car on run-flats at speeds of up to 50mph.

Educating drivers

Graham Rixon suggests the main hurdle for run-flats is driver understanding.

“There’s not huge awareness as to how run-flat tyres should be used, such as how fast they can go or how far they can travel once a puncture has taken place.”

The accepted view is that a vehicle can be driven 50 miles (at 50mph).

However, James Bailey says this is a conservative estimate, based on a fully-loaded car.

BMW says with low loads, one or two people without luggage, the car can be driven 150 miles at a maximum speed of 50mph.

Run-flat tyres also eliminate the need for a spare wheel.

This reduces weight and should, in theory, improve fuel economy.

 

Take-up

Few car manufacturers fit run-flats as standard and they do not represent a large share of the market.

In fact, Michelin says they make up just over 2% of the UK market.

Both Michelin and Bridgestone say this figure is on the increase, however.

Bridgestone says there was a five-fold increase in the take-up of run-flat tyres in the fleet market between 2005 and 2008.

ATS Euromaster says the number of run-flats purchased as part of the overall product mix increased by 2.4% in 2008, against figures for 2007.

Most manufacturers agree that the take-up of run-flats relates almost directly to the number of BMWs on a fleet, as BMW fits run-flats as standard on many models.

Other manufacturers offering run-flats on certain models include the Volkswagen Group, Ford, Lexus and Toyota, but the take-up is relatively small.

Retro-fitting run-flat tyres is possible, but fleet managers should seek advice from their vehicle manufacturers first.

They should not be mixed with conventional tyres and the vehicle must have a tyre pressure monitoring system fitted as it is not always possible to tell when a run-flat tyre has a puncture.

Extra cost

So why aren’t run-flats more popular?

Cost is one of the main factors.

Prices can be 10% to 30% more than a standard tyre, depending on the size and type of tyre.

Michelin and Continental say the extra cost is due to the additional raw material used in the tyres.

“Few people are willing to pay the extra, especially if they don’t fully understand the benefits,” says LeasePlan’s Rixon.

And it is worth bearing in mind that tyre prices in general increased 20% last year and could rise further.

ATS Euromaster claims costs can be reduced by repairing rather than replacing run-flats.

However, it will only carry out minor repairs, such as where a nail has pierced the central area of the tread, and it is subject to a strict verification process.

If the tyre has been repaired before then it must be replaced. ATS Euromaster admits that, in most cases, punctured run-flat tyres end up being replaced.

Mike Wise, head of Kwik-Fit Fleet, says run-flats should not be repaired following a puncture as it is not always possible to determine how many miles the tyre has been driven in a punctured state.

But he does believe the benefits of run-flats outweigh the cost.

“No one wants a puncture at any time. Let alone late at night.”

And Hitachi’s Bowden agrees, for a different reason. “More and more vehicles are coming without a spare, so I would prefer to have run-flat capability, even at an extra cost.”

Uncomfortable ride?

James Bailey says run-flats had a bad press three to five years ago, with complaints about ride quality.

He puts this down to run-flats being originally engineered for armoured vehicles.

“They were meant to get a president through a war zone, rather than get you home from work safely.

"Compound ingredients are a lot more subtle now, and you can have high performance and run-flat capability.

"The Nissan GT-R set the fastest time at the Nürburgring on run-flats.”

BMW says the latest generation tyres are as comfortable as ‘normal tyres’.

A spokesman said: “The first generation of run-flats BMW used were not engineered with the car, but subsequent generations have been.”

Availability is another complaint levied against run-flats. Lloyds TSB Autolease, Hitachi Capital Vehicle Solutions and LeasePlan have all experienced problems with tyre retailers not always having them in stock.

However, Mike Wise says Kwik Fit will generally have them in stock.

Run-flats are also thought to survive fewer miles, but this is subjective and depends on driving style.

Bailey argues that run-flats will do more miles because of their tougher construction and the tyre pressure warning system will encourage drivers to check tyre pressure more regularly, thus prolonging the life of the tyre.

George Reid, head of technical services at Lloyds TSB Autolease, says he managed 30,000 miles on run-flats.

It appears that fleet managers will have to find the line between cost and safety when deciding whether run-flats are the best way to tackle punctures.

What's your view?

Fleet News has heard complaints about run-flats losing pressure, with no sign of a puncture.

BMW says it has no record of run-flats losing pressure and tyre manufacturers say there is no reason for tyres to lose pressure unless they have a puncture, have not been fitted correctly or have a leaking valve.

Fleet News is keen to hear your views. Have you had a good or bad experience with run-flats? Email sarah.tooze@bauermedia.co.uk

Fleet News' experience of run-flats

by Gareth Roberts

It’s the end of another day at the office and I join the rest of humanity who are single-minded in their desire to get home.

The only problem is that two minutes into my 12-mile journey a red warning light appears on the dash, telling me I’ve lost tyre pressure.

I pull over, cursing my luck, and begin preparing myself for some unexpected road-side overtime getting my hands dirty changing the wheel.

But, hang-on… I’m driving a BMW 320d sporting run-flats.

When you’ve always been told not to drive on a flat tyre, it’s a difficult concept to grasp, initially. I continue my journey at a much reduced rate of knots.

But the handling feels compromised, at any speed, and doesn’t fill me with confidence.

I’m constantly correcting the steering and, while I’m sure my route along winding country roads doesn’t help matters, I’m relieved when I get home.

There’s also the relief that there was no wheel to change, but the following day a £150-plus bill for a new tyre puts that into perspective.

But at least I’m sat in the warm debating the pros and cons.