No Nail, No Bullet: Secrets of Impenetrable Special Vehicle Tires

2024 Author: Seth Attwood | [email protected]. Last modified: 2023-12-16 15:55

Cars for performing special tasks, including military ones, must be equipped with special tires, for which neither a banal puncture nor a bullet hit is terrible. What are protected tires, and what are they? "Army Standard" studied the history of the issue and the latest innovations.

From time immemorial

John Dunlop began producing the first pneumatic bicycle tires in 1889, and the first inflatable tires on automobiles appeared in 1895 thanks to Edouard Michelin. Pneumatic tires became widespread and replaced monolithic ones only in the second quarter of the twentieth century. Before that, wheels made of a solid rubber layer prevailed, and then of gusmatic - a type of monolithic tire, but with an elastic inner layer of porous rubber that replaced air.

In military equipment, these tires lingered even longer - a nail and a bullet did not harm them, and such wheels were widely used in combat vehicles of the First and Second World Wars. By the way, gusmatics are used to this day, but not on army vehicles, but on completely peaceful ones - mainly on low-speed special equipment such as warehouse loaders or tractors.

There are also rarities. For example, in the museum of the studio "Mosfilm" there is a working German truck "Magirus" of 1912 release, which is on the move, the native rubber wheels of which have been preserved in working order to this day - on them, during filming, an old truck sometimes pulls out of the mud stuck modern cars!

Well, now, from antiquity to modern "impenetrable wheels".

Wheel in wheel

The simplest and most obvious technology with which you can continue to move on a tire that for some reason has escaped air is an internal rigid insert in the form of a thick ring between the wheel and the tire. This technology appeared quite a long time ago and is still used today, since it is relatively simple and inexpensive.

A special ring made of dense fiberglass or other durable and lightweight plastic is installed on the disk in the form of two split halves, after which a regular rubber tire is mounted on top. The system is quite reliable, and allows you to leave the danger zone even with a shot through the wheel, while maintaining controllability on the go.

However, the area of contact with the road at such a wheel in a punctured state still becomes smaller, and at high speed it becomes difficult and dangerous to steer a car. Plus, the weight is higher, the balancing requirements are higher and the tire mounting is more difficult. For these reasons, such wheels are used mainly on special vehicles for protected persons, which are driven by trained ace drivers.

Under pressure and without

The development of the tire industry and chemical technologies made it possible to move to a qualitatively new level in the field of wheel protection - not to protect ordinary tires with additional means, but to integrate the safety system directly into the tire! Thanks to this, the unafraid of loss of pressure, the wheels have moved from the class of armored VIP cars and police-military vehicles to the world of civilian vehicles.

The technology has the general conditional name "Run Flat" and is used by various tire manufacturers - with minor differences. Such wheels are supplied to the conveyors of well-known car brands and are sold at retail for any car.

At the same time, the essence of the technology is generally simple. The Run Flat tire has a special thick and stiff sidewalls, which, when air pressure is lost, retain their profile shape, without flying off the wheel even with side loads on bends and allowing you to travel a fairly long distance at moderate speeds. At the same time, externally and internally, the wheel is no different from the usual one. The disadvantages of the Run Flat system include excessive wheel stiffness, which makes driving a car less comfortable and more noisy. This is the price to pay for the safety margin.

Chemistry inside

Another way to protect the wheel from spikes and bullets is to add a special chemical composition inside, which, when punctured, begins to come out and polymerize, plugging the hole. There are many such mixtures, they are of varying degrees of effectiveness. One of them, developed by the domestic Research Institute of the Tire Industry, was used, among other things, in the presidential special-purpose garage. Wheels that are not afraid of punctures and bullets were made for this garage from the 80s to the early 2000s at a pilot plant at the Research Institute. The tire was called I-287 "Granite" and was produced in dimensions 15 and 16 inches for the government ZIL-41047. These tires were not sold to private individuals.

The technology was based on the so-called hermetic composition based on oligomers - a viscous thick composition that was applied to the inner surface of the tire. If the tire was damaged, the hermetic composition was squeezed out, and it plugged the hole.

The diameter of the hole, from which it was possible to move without loss of pressure, was 11.5 mm and was designed to be hit by a bullet! In this case, after tightening the hole, the composition retained its operability for the following damages.

Back to the Future

Well, since, as you know, technologies often develop "in a spiral", evolution, having gone through the era of ingenious means of maintaining pressure in a pneumatic tire … came again to an airless tire, with which (albeit in a different form) everything began once!

Modern technologies have made it possible to make such a tire not only for army armored vehicles, but also for completely civilian SUVs and ATVs.

Airless tires are being developed in parallel by different companies around the world, and they can be found under the names Terrain Armor, Airless Resilient NPT, X Tweel SSL and others. In general, innovative wheels are a spatial honeycomb structure made of a special polymer, durable and elastic. It performs a shock-absorbing function due to its own elasticity and does not need air pressure. Cellular wheels cannot be punctured, ripped through, shot through - or rather, of course, it is possible, but from this they practically will not lose their functionality!