Ground pressure

Short description: Pressure exerted on the ground by the tires or tracks of a motorized vehicle

Ground pressure is the pressure exerted on the ground by the tires or tracks of a motorized vehicle, and is one measure of its potential mobility,[1] especially over soft ground. It also applies to the feet of a walking person or machine. Pressure is measured in the SI unit of pascals (Pa). Average ground pressure can be calculated using the standard formula for average pressure: P = F/A.[2] In an idealised case, i.e. a static, uniform net force normal to level ground, this is simply the object's weight divided by contact area. The ground pressure of motorized vehicles is often compared with the ground pressure of a human foot, which can be 60 – 80 kPa while walking or as much as 13 MPa for a person in spike heels.[3]

Increasing the size of the contact area on the ground (the footprint) in relation to the weight decreases the unit ground pressure. Ground pressure of 14 kPa (2 psi) or less is recommended for fragile ecosystems like marshes.[4] Decreasing the ground pressure increases the flotation, allowing easier passage of the body over soft terrain. This is exemplified by use of equipment such as snowshoes.

## Contents

* 1 Examples
* 2 See also
* 3 Related reading
* 4 References

## Examples

All examples are approximate, and will vary based on conditions

Object  | Ground pressure (kPa)  | (psi)

|
|

Hovercraft  | 0.7  | 0.1
Human on snowshoes | 3.5  | 0.5
Rubber-tracked ATV | 5.165  | 0.75
Wheeled ATV  | 13.8  | 2
Diedrich D-50 – T2 drilling rig  | 26.2  | 3.8
Human male (130 kg, standing on one foot)  | 55  | 8
Average human, flat shoes[5] | 17  | 2.5
M1 Abrams tank[6] | 103  | 15
1993 Toyota 4Runner / Hilux Surf  | 170  | 25
Adult horse (550 kg, 1250 lb)  | 170  | 25
Bagger 288 excavation machine  | 170  | 25
Passenger car  | 205  | 30
Adult elephant | 240  | 35
Mountain bicycle | 245  | 40
Road racing bicycle | 620  | 90
Commercial semi truck/Lorrie  | 793  | 115
Stiletto heel  | 3,250  | 471

Note: The pressures for average human and horse are for standing still position.[7] A walking human will exert more than double his standing pressure. A galloping horse will exert up to 3.5 MPa (500 psi). The ground pressure for a pneumatic tire is roughly equal to its inflation pressure.

## See also

* Contact patch
* Tire load sensitivity

## Related reading

* Theory of Ground Vehicles [8]

## References

1. ↑ Allen, Jim. Jeep 4 X 4 Performance Handbook. MotorBooks/MBI Publishing Company. p. 16. SBN 076030470X.
2. ↑ Wenger, Karl F. (1984). Forestry Handbook. New York : Wiley. p. 499. ISBN 0-471-06227-8.
3. ↑ J. William Thompson; Kim Sorvig (2000). Sustainable Landscape Construction: A Guide to Green Building Outdoors. Island Press. p. 51. ISBN 1-55963-646-7. https://archive.org/details/sustainablelands0000thom/page/51.
4. ↑ "Page 4 of Management of small dock and piers, best management practices, May 2005 NOAA". http://coastalmanagement.noaa.gov/initiatives/media/bmp.pdf.
5. ↑ J. William Thompson; Kim Sorvig (2000). Sustainable Landscape Construction: A Guide to Green Building Outdoors. Island Press. p. 50. ISBN 1-55963-646-7. https://archive.org/details/sustainablelands0000thom/page/50.
6. ↑ mathscinotes (2016-06-10). "Tank Track Ground Pressure Examples" (in en-US). https://www.mathscinotes.com/2016/06/tank-track-ground-pressure-examples/.
7. ↑ J. William Thompson; Kim Sorvig (2000). Sustainable Landscape Construction: A Guide to Green Building Outdoors. Island Press. p. 50. ISBN 1-55963-646-7. https://archive.org/details/sustainablelands0000thom/page/50.
8. ↑ Wong, Jo Yung (2001). Theory of Ground Vehicles. New York : John Wiley. ISBN 0-471-35461-9.

* v
* t
* e

Tires

Types|

* Tubeless tire
* Radial tire
* Low rolling resistance tire
* Run-flat tire
* Michelin PAX System
* Airless tire
* Tweel
* Rain tyre
* Snow tire
* All-terrain tire
* Bar grip
* Knobby tire
* Large tire
* Mud-terrain tire
* Paddle tire
* Orange oil tires
* Whitewall tire
* Aircraft tire
* Tundra tire
* Bicycle tire
* Tubular tire
* Lego tire
* Motorcycle tyre
* Tractor tire
* Racing slick
* Formula One tires
* Spare tire
* Continental tire

Components|

* Bead
* Beadlock
* Tread
* Siping (rubber)
* Valve stem
* Dunlop valve
* Presta valve
* Schrader valve

Attributes|

* Camber thrust
* Circle of forces
* Cold inflation pressure
* Contact patch
* Cornering force
* Ground pressure
* Pacejka's Magic Formula
* Pneumatic trail
* Relaxation length
* Rolling resistance
* Self aligning torque
* Slip angle
* Steering ratio
* Tire balance
* Tire load sensitivity
* Tire uniformity
* Lateral Force Variation
* Radial Force Variation
* Traction (engineering)
* Treadwear rating

Behaviors|

* Aquaplaning
* Groove wander
* Slip (vehicle dynamics)
* Tramlining

Maintenance|

* Tire maintenance
* Tire rotation
* Bicycle pump
* Central Tire Inflation System
* Tire mousse
* Tire-pressure monitoring system
* Tire-pressure gauge
* Direct TPMS
* Bead breaker
* Tire changer
* Tire iron

Life cycle|

* Tire manufacturing
* List of tire companies
* Retread
* Waste tires
* Tire recycling
* Tire fire
* Blowout
* Flat tire
* Ozone cracking

Organizations|

* European Tyre and Rim Technical Organisation
* Tire Society
* Tire Science and Technology

Identification|

* Tire code
* Plus sizing
* Tire label
* Uniform Tire Quality Grading (UTQG)

* Outline of tires
* Category

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