The Physics
Factbook
An encyclopedia of scientific essays

# Pressure in a Bicycle Tire

Bibliographic Entry Result
(w/surrounding text)
Standardized
Result
Zitzewitz and Neff. Merrill Physics Principles and Problems. Westerville, Ohio: Harvard University and Cornell, 1990. 267.
Some Typical Pressures
Location Pressure (Pa)
Auto Tire 2 × 105
200 kPa
"Pressure." Macmillan Encyclopedia of Physics Reference. 530.03M. Volume 3. New York, New York.1996. pages 1235-1236. "Tire pressure are measured using a rather simple spring gauge, giving readings such as "29", meaning 29 psi." 200 kPa
Bernie, Jacques. Edmonton Bicycle Commuters Society (EBC) Mechanic's Corner. 2002-2003. "Bicycle tires have a pressure rating stamped right on the wall. Look for the words: "inflate to 90 psi max …. Some tires indicate a minimum and a maximum tire pressure. They will say: OFF ROAD 45 psi, ON ROAD 65 psi" 300–600 kPa
Correct Tire Pressure Improves Your Ride. Mike's Bicycle Centers and Sausalito Cyclery Create Catalog. 2001.
Rider Weight Road Tire Pressure (PSI) Off-Road Tire Pressure (PSI)
110 95-105 35-38
140 105-115 37-40
170 110-120 40-43
200 120-130 42-45
230 125-135 45-48
240–930 kPa

Pressure is any force which acts against a surface. The formula to define pressure is P = F/A where F is force and A is surface area. The SI unit for pressure is the pascal (Pa = N/m2 = kg/ms2) or kilopascal (kPa = 1000 Pa) but some mechanics use psi (pounds-force/square inch).

It is very hard to find an exact number of pascals (pressure) for a bicycle tire because there are different types of bicycles tires. For example, off the road bicycle tires have a pressure between 310 to 450 kPa. On the other hand, road tires have a higher pressure between 660 to 930 kPa. The reason for this is because the road is very rough and hard but the regular ground is, in a way, smooth and soft. Another reason to keep tire pressure higher on the road is because if you have a soft tire, it will pick up glass and dirt off the road. These will then stick to the tire and damage your inner tube.Then after a while, you would get a flat.

Shara Khan -- 2003