A central tire inflation system (CTIS) is a system to provide control over the

air pressure Atmospheric pressure, also known as air pressure or barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The Standard atmosphere (unit), standard atmosphere (symbol: atm) is a unit of pressure defined as , whi ...

in each of a vehicle's

tires A tire (North American English) or tyre (Commonwealth English) is a ring-shaped component that surrounds a wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide traction on the surface over w ...

as a way to improve performance on different surfaces.

Uses

Lowering the air pressure in a tire creates a larger

contact patch The contact patch is the portion of a vehicle's tire that is in actual contact with the road surface. It is commonly used in the discussion of pneumatic (i.e. pressurized) tires, where the term is used strictly to describe the portion of the tire' ...

between the tire and the ground, and makes driving on softer ground much easier. It also does less damage to the tire surface. This is important on work sites and in agricultural fields; by giving the driver direct control over the air pressure in each tire, maneuverability is greatly improved. Softer tires also cushion against rough terrain and road damage, such as

washboarding Washboarding or corrugation is the formation of periodic, transverse ripples in the surface of Gravel road, gravel and Dirt road, dirt roads. Washboarding occurs in dry, granular road material with repeated traffic, traveling at speeds above . ...

, more effectively. Reducing tire pressure also reduces the extent to which the tires grind against loose surfaces, significantly reducing dust and silt. Another function of CTIS is to maintain tire pressure if there is a slow leak or puncture. In this case, the system controls inflation automatically based on the selected pressure the driver has set. CTIS also extends truck, tire, and drive train life, by significantly reducing vibration and shock loading. Feedback from Australian logging contractors show a doubling of transmission and differential life.

Applications

The technology is extensively used in many off-road transport operations. In many countries, especially Australia, New Zealand and South Africa, CTIS is used in logging, mining, and power line maintenance, as it significantly reduces environmental impact when transporting logs, or travelling on gravel or dirt roads. From 1984,

General Motors General Motors Company (GM) is an American Multinational corporation, multinational Automotive industry, automotive manufacturing company headquartered in Detroit, Michigan, United States. The company is most known for owning and manufacturing f ...

offered CTIS for the Chevrolet Blazer and various pickups.

AM General AM General is an American heavy vehicle and contract manufacturer, contract automotive manufacturer based in South Bend, Indiana. It is best known for the civilian Hummer H1, Hummer and the military Humvee that are assembled in Mishawaka, Indiana. ...

also offered CTIS for the civilian

Hummer H1 The Hummer H1 is a full-size four-wheel-drive utility vehicle based on the M998 Humvee, which was developed by AM General when it was a subsidiary of American Motors Corporation (AMC). Originally designed strictly for military use, the off-r ...

vehicle. There have been attempts at employing central tire inflation systems on

aircraft An aircraft ( aircraft) is a vehicle that is able to flight, fly by gaining support from the Atmosphere of Earth, air. It counters the force of gravity by using either Buoyancy, static lift or the Lift (force), dynamic lift of an airfoil, or, i ...

landing wheels (notably on the

Soviet The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

Antonov An-22 military transport) to improve their preparedness for unpaved

runway In aviation, a runway is an elongated, rectangular surface designed for the landing and takeoff of an aircraft. Runways may be a human-made surface (often asphalt concrete, asphalt, concrete, or a mixture of both) or a natural surface (sod, ...

Military use

CTIS was first used in production on the American

DUKW The DUKW (GMC type nomenclature, colloquially known as Duck) is a six-wheel-drive amphibious modification of the GMC CCKW "deuce-and-a-half" 2½-ton trucks used by the U.S. military during World War II and the Korean War. Designed by a part ...

amphibious truck, which was introduced in 1942. The

Czech Czech may refer to: * Anything from or related to the Czech Republic, a country in Europe ** Czech language ** Czechs, the people of the area ** Czech culture ** Czech cuisine * One of three mythical brothers, Lech, Czech, and Rus *Czech (surnam ...

Tatra T813's central inflation and deflation system was designed to maintain pressure even after multiple bullet punctures. Military-spec Tatra trucks are equipped with CTIS as standard. Several trucks used by the U.S. military, such as the

HMMWV The High Mobility Multipurpose Wheeled Vehicle (HMMWV; colloquial: Humvee) is a family of Military light utility vehicle, light, four-wheel drive Military vehicle#Military trucks, military trucks and utility vehicles produced by AM General. It ...

HEMTT The Heavy Expanded Mobility Tactical Truck (HEMTT) is an eight-wheel drive, diesel-powered, tactical truck. The M977 HEMTT first entered service in 1982 with the United States Army as a replacement for the M520 Goer, and since that date ha ...

, and FMTV, are equipped with CTIS. The feature is also common in Soviet and Russian military trucks.

References

{{Tires, state=collapsed Tire inflation