Although fuel plays a mojor rolle in powering vehicles to move a vehicles tires play an even more integral role in the overall performance of the vehicle, as it dictates its handling, traction, ride, comfort and fuel consumption; as it is the main component that interacts with the surface being driven on (Rezna, 2008). Thus if the condition of the tires is improper the performance of the vehicle will be affected. One negative tire condition that can occur is low tire pressure/ under inflation. According to the Websters dictionary, under inflation is the insufficient presence of air pressure in a tire for the amount of load carried and vice versa for over inflation. This paper will examine the causes of reduced tire pressure, the tire pressure in places abroad, effects of under and over inflated tires, and tire pressure as it relates to furl consumption. To begin with, tire pressure is a measure of the amount of air in a vehicles tires, in pounds per square inch (psi) (Car Talk Service Advice: Tire Pressure, 2005).
There is no standard psi for all tires however tires are marked with a recommended psi that should be adhered to for optimum performance in vehicles. Under inflation of tires can be cause by various factors such as natural causes and the negligence of drivers. Due to temperature and natural cause variation about 1 pound per square inch of pressure to 1° degree Fahrenheit is lost every month (NHTSA, Tire Pressure Monitoring Final Part 3). This loss of pressure is known as natural leakage. Therefore, as the temperature of the climate or air changes, the pressure in the tire will change. Hence, under inflation of the tire will be increased. According to data from the tire industry, 85 percent of all tire air pressure losses are the result of slow leaks that occur over a period of hours, days, or months.
Only 15 percent are rapid air losses caused by contact with a road hazard (Source???). An example of the natural hazards that can be present that contribute to under inflation may be a nail present in the road that may puncture the tire (source if any). Additionally, due to the negligence of passengers to frequently check their tires under inflation can be an effect. As passengers frequently check their tires pressure they can decrease the rate at which the natural leakage of their tires air occurs. Moreover, A survey done by NASS-CDS crash investigators, in February 2001 identified that 39% of passenger cars and 46% of passenger trucks had at least one tire pressure that was 6psi or more below placard (recommended/labeled) pressure.
In other words a considerable amount of passenger cars and almost half the passenger trucks tested were underinflated. The amount of cars surveyed and tested at this time was 5,967 passenger cars and 3,950 light trucks for a total of 9,917 vehicles across a total of 336 gas stations in the United States of America (National Automotive Sampling System Crashworthiness Data System, 2001). The below chart is a data collected from the NASS-CDS survey in 2001 and represents the percentages of passenger cars and light trucks and their amount of tires 20% or more below placard pressure. (National Automotive Sampling System Crashworthiness Data System, 2001)
Number of Tires
20% or more
Below PlacardPassenger CarsPercentLight TrucksPercent
It is seen that a smaller percentage of vehicles (passenger cars and light trucks) had all four tires underinflated large amounts had at least one tire underinflated which can still affect the cars performance. Additionally, according to an informal study done by students at Carnegie Mellon University, it was discovered that of the 81 cars they tested, the four tires of each car tested were underinflated by an average of 20% (Gearson 2005). Furthermore, with under and over inflated tires there are some effects that can impact the drivers safety, the tires life expectancy, its rolling resistance and the use of fuel. Due to the loss of pressure in the tires, underinflated tires footprints or tread are enlarged. When the tires foot print is enlarged the rolling resistance of the tire is greater (Source). Rolling resistance can be defined as the friction between the road and the tire and the tires ability to effectively grip the road and ride smoothly (source).
Unfortunately, with an under inflated tire in the instance of wet roads, the tires are more likely to slide and cause accidents and crashes. Therefore, this result in a larger friction to overcome and more rubber of the tire burnt. Due to the lack of control over the vehicle the tread life of a tire can be decreased. According to Good year, a renowned tire manufacturing company, under inflated tires wears more rapidly than they should as compared to properly inflated tires (source). The company Good Year makes their tires out of rubber. This rubber is easy to burn and wear due to the pressure applied on an under inflated tire to carry a heavy load. As for over inflated tires, the tires cannot isolate road irregularities well, causing them to ride harsher (uncomfortably) (Proper Tire Inflation). This can also result in the traction and the tireprint/footprint of the vehicle to be reduced ( Rezna 2008). If the tireprint is reduced, this means that the surface contact area is reduced also thus more pressure is being applied to the area in contact with the road.
Inturn the tires are more likely to be damaged when running over potholes or debris in the road because the pressure applied from the weight of the car is greater. However, higher inflation pressures usually provide an improvement in steering response and cornering stability up to a point (Proper Tire Inflation). Moreover, over inflation can result in the transmission of shock loads by the tires to the suspension which can then diminish its ability to support the necessary load for cornerability, braking and acceleration (Rezna 2008). Finally, the fuel usage or consumption of vehicles is varied dependant on the pressure in the tires. This can account for at least one tire being under or over inflated.
According to the National Research Council, the main factor associated with fuel consumption and tire pressure is rolling resistance. The make-up of a car also plays an important role in how fuel is consumed. The engine is directly connected to the axles that hold all four or more tires into place. The engine has to use this fuel to increase the transfer of power to the axles. As the fuel is inserted into the car, the engine then converts that fuel into mechanical energy and that energy is transmitted to the axles to turn the wheels (National Research Council, 2006).
Therefore, if the tire is under inflated or over inflated the aero dynamic drag that is present between the tires and the road will place for strain on the engine to exert more pressure to move the vehicle and the fuel consumption will increase. Conclusively, there are many benefits that can be derived by monitoring and maintaining the correct tire pressure. They include improved fuel efficiency, better handling, better overall performance, overall safety, as well and an increased tire life span. In addition to these direct benefits, there is also the intangible benefit to the environment of decreasing green-house gases by improved fuel management. The overall benefit of this factor remains priceless.
Bent, R., Orr, L., & Baker, R. (Eds.). (2002). Energy: Science, Policy and the Pursuit of Sustainability. Washington, DC: Island Press. Car Talk Service Advice: Tire Pressure. (2005, April 29). Retrieved February 22, 2012, from Cars Talk: http://cars.cartalk.com/content/advice/tirepressure.html Enzler, S. (2010, March). Fossil fuels: Characteristics, origin, applications and effects of fossil fuels. Retrieved February 18, 2012, from Lenntech: http://www.lenntech.com/greenhouse-effect/fossil-fuels.htm Gearson, B. (2005). Carnegie Mellon Today: Save Gas, Money and the Environment with Properly Inflated Tires. Retrieved on 23rd February 2012 from http://www.cmu.edu/cmnews/extra/050921_tire.html National Automotive Sampling System Crashworthiness Data System. (2001). Tire Pressure Survey
and Test Results. Retrieved February 22, 2012, from National Highway Traffic Safety Administration: http://www.nhtsa.gov/cars/rules/rulings/tirepressure/LTPW3.html National Research Council. (2006). Tires and Passenger Vehicle Fuel Economy: Informing Consumers, Improving Performance. Retrieved February 19, 2012 from http://onlinepubs.trb.org/onlinepubs/sr/sr286.pdf Proper Tire Inflation. (n.d.). Retrieved February 23, 2012, from Nitrogen Tire Inflation Systems: http://www.nitrogentiremachine.com/proper_tire_inflation.htm Rezna, J. (2008). Vehicle Dynamics: Theory and Application. Retrieved on 22nd February from http://books.google.bs/books?hl=en&lr=&id=Pvsv78xj7UIC&oi=fnd&pg=PR10&dq=under+and+over+inflatedness+in+car+tires&ots=1nBohNoAmt&sig=f0lQjo7DOYj_rim44o1xjewch8#v=onepage&q=under%20and%20over%20inflatedness%20in%20car%20tires&f=true pgs. Turnquest, P. G. (2005, August 17). Tribune. Gas price breaks $4 mark , p. 1.
Car Talk Service Advice: Tire Pressure. (2005, April 29). Retrieved February 22, 2012, from Cars Talk: http://cars.cartalk.com/content/advice/tirepressure.html Enzler, S. (2010, March). Fossil fuels: Characteristics, origin, applications and effects of fossil fuels. Retrieved February 18, 2012, from Lenntech: http://www.lenntech.com/greenhouse-effect/fossil-fuels.htm Factors Affecting Truck Fuel Economy. (n.d.). Retrieved February 22, 2012, from Good Year: http://www.goodyeartrucktires.com/resources/factors-fuel-economy.aspx Proper Tire Inflation. (n.d.). Retrieved February 23, 2012, from Nitrogen Tire Inflation Systems: http://www.nitrogentiremachine.com/proper_tire_inflation.htm West,L. (n.d.). Keeping you tires Inflated could help save the planet, and your life. Retrieved on 23rd February 2012 from http://environment.about.com/od/greenlivingdesign/a/tire_pressure.htm
Bent, R., Orr, L., & Baker, R. (Eds.). (2002). Energy: Science, Policy and the Pursuit of Sustainability. Washington, DC: Island Press. Car Talk Service Advice: Tire Pressure. (2005, April 29). Retrieved February 22, 2012, from Cars Talk:
http://cars.cartalk.com/content/advice/tirepressure.html National Automotive Sampling System Crashworthiness Data System. (2001). Tire Pressure Survey and Test Results. Retrieved February 22, 2012, from National Highway Traffic Safety Administration: http://www.nhtsa.gov/cars/rules/rulings/tirepressure/LTPW3.html Population Change and Distribution. (2001, April). Retrieved February 2012, from US Census Bureau: http://www.census.gov/prod/2001pubs/c2kbr01-2.pdf Proper Tire Inflation. (n.d.). Retrieved February 23, 2012, from Nitrogen Tire Inflation Systems: http://www.nitrogentiremachine.com/proper_tire_inflation.htm