An essential movement of any security vehicle - armoured limousine, VIP escort, SWAT. Police or commercial cash-in-transit (CIT) vehicle - is its ability to continue moving with one or more tyres damaged. This is for more tyres damaged. This is for two main reasons . The first relates to the vulnerability of most armour materials. Armour glass, for example. is designed to withstand a limited number of strikes from a given range of weapons. Typically a 40mm thick construction of glass/ polycarbonate will stop three shots from a military rifle firing ball ammunition if the strikes are spaced 100mm apart. Increase the number of strikes or bring them closer together and the glass will fail. The second has to do with retailing mobility which is vital in an emergency.

The runflat requirement, in terms of distance numbers of tyres damaged, depends on the protected vehicle. With a VIP limousine/ escort entourage, the protected vehicles should have sufficient high speed runflat capability to get the VIP to a place of safety with one or two tyres damaged. This should rarely involve a journey of more than 15 km. A police riot vehicle, on the other hand, may need to retain traction and steering control with all tyres damaged, but only for sufficient distance to clear the immediate area of disturbance. A CIT vehicle requirement is different yet again. given the limitations of armour and the duty of care to driver and crew, the vehicle should have the ability to clear the immediate ambush. Runflat capability, in this case is not there to complete a delivery but to avoid harm to personnel.

Until recently, the international yardstick against which Runflat capability was the US Military and European Military FINABEL standards. These are a carry over from a World War 2, during which occurred the famous incident of the two British armoured Scout cards fitted with the first generation "Combat" tyres, withdrawing from an engagement to dash across fifty miles of desert with tyres shot out to get within radio range to signal a major movement of German forces.

Medals were handed out and the principle adopted that combat vehicles must be able to complete a mission with damaged tyres, irrespective of the cost and consequential mechanical slide effects. This led to the increased fitting of expensive, heavy thick wall "combat" tyres, with sidewalls strong enough to support the weight of the vehicle at zero pressure, or solid rubber insert stuffed into standard production tyres.

The US military set 30 miles (50 km) at 30 miles (50 km) an hour with one front and one rear tyre damaged as the US standard for combat vehicles, while the European Finabel standard, possibly because of the limitations of the systems then available, set a compromise. This was 50 km with one front and one rear tyre damaged, with the first 3km at "maximum escape speed" (limited at the outset to 70 km/hr), followed by 10 km at 50 km/hr and finishing with 37 km at 20-25 km/hr. "Damage" was set at 5 shots into side wall of 20" tyre, followed by two into the tyre tread from a 7.62mm NATO rifle firing ball ammunition form arrange of 50 metres.

With the change in roles from combat to peace keeping and public order operations the server5e shortcomings of the traditional runflat systems became all too patient. Combat tyres are treacherous on wet roads and have limited tread life. The are not longer fitted. Solid rubber inserts are, but they need special wheels, expensive equipment to fit, play havoc with modern truck suspension and braking systems and leave crews complaining of hard ride symptoms. And now that running costs over the working the working life of vehicular part of the procurement analysis, shipping 20" diameter wheel assemblies over vast distances to have a punctures repaired has given greater impetus to the search for more up to date alternatives.

Then there is the drive to avoid casualties. The rules of engagement have changed. The ubiquitous RGP rocket fired from a roadside ditch can punch a hole in most APCs. So if a vehicle comes under attack, the rule is: identify the source and withdraw. Threats can be handled from a distance, so avoiding the need for body bags. This is cost-effective policy. If the runflat requirement is set at a realistic level fifty year old remedies become obsolete. Modern lightweight Runflat inserts can be fitted to standard production wheels and off-the-shelf truck tyres, allowing fitment and tyre changes in a ny tyre shop. They are tailored to give a predictable Runflat distance under given operational conditions. military intervention operations over the last 10 years indicate that in the majority of them the ability to continue at speeds up to 50 km/hr for a distance of 15-20 km with damaged tyres serves the operational need. And this can be achieved with standard wheels and tyres. Modern inserts have a minimum adverse effect on vehicle ride and performance at inflated pressures so this is critical benefited can be extended to all types of operational vehicles.

This revised thinking has generated modern Runflat standards for all categories of security vehicles. These take of higher road speeds, the need for systems that can be fitted anywhere in the world and the wide range of operating conditions. As with modern military runflat systems, the aim is to supply systems that can be fitted to standard production wheels and tyres to allow operation over tarmac or earth roads.

Again, as with military vehicles, the assumption is that the worst case firearms attack pattern is on which two tyres down one side of the vehicle. The ballistic test standard calls for two shots from a 9mm pistol from a range of 10 metres and one shot from a military rifle (7.63 NATO rifle firing ball ammunition) from a range of fifty metres,fried at three aiming marks set out at equidistance around the circumstance of the tyre sidewall on wheels of 16", 17", 17.5" and 19.5" diameteres. The test wheel is the fitted to the front position of the test vehicle.

The rear wheel on the same side is then replaced with a Runflat fitted wheel assembly and the tyre deflated. The test vehicle must them complete one or the other of the Runflat distances; that is:

Level 1

15 km continuous running with one from and one rear tyre deflated at speeds up to 50 km/hr on made up tarmac or earth roads under simulated urban travel conditions, that is , with curves, bends and at least two emergency stops. The tyre temperatures should be noted at the start of the trial, at the 7.5 km distance in the trial and at the end of the trial. While tyre damage is permitted the must remain on the wheels.

Level 2

50 km 15 km continuous running with one from and one rear tyre deflated, with the first 3 km at maximum escape speed to a limit of 80 km/hr, followed by 10 km at 50 km/hr and the balance of 37 km between 20 and 25 km/hr. The trial is to be carried out on made up tarmac or earth roads under simulated urban travel conditions, that is, with curves, bends and at least two emergency stops. The tyre temperatures should be noted at the start of the trial, at 3, 10, 20 and 30 km distances in the trial and at the end of the trial. While tyre damage is permitted they must remain on the wheels.

25 years experience in Runflat design and operation suggests that Level 1 or Level 2 meets the Runflat requirement for most security vehicle operations. Where they do not, it is for the vehicle user to set out his or her different requirements and for the system supplier to make proposals as to how theses different requirements can be met. in some cases, these needs are met by fitting the new generation "Runflat low profile tyres" developed by major tyre manufactures. These can be fitted to standard wheel rims. Where "Runflat" tyres are not available Runflat inserts are fitted to the standard wheels and tyres.

If one lesson can be drawn from the radical changes in worldwide armed confrontations over the last ten years it is that a wheeled security vehicle without Runflat capability should not have bed there!