Normal air pressure when driving is 100-120 psi.

Normal air pressure when driving is 100-120 psi.

• A. 60-80
• B. 80-100
• C. 100-120
• D. 140-160

Answer: (C)

Maintaining proper tire pressure is essential for handling, tire life, and safety, especially on fire apparatus with heavy loads. The operating range of 100 to 120 psi is appropriate for many heavy-duty tires during regular driving because it keeps the tire under enough load to maintain a stable contact patch with the road and to support the vehicle’s weight. If pressure is too low, the tire flexes more, overheats, wears unevenly, reduces handling, and increases the risk of a blowout. If pressure is too high, the contact patch becomes too small, reducing traction and braking grip, making the ride harsher, and causing excessive center-tread wear. Always follow the tire sidewall and vehicle placard specifications, and check pressures when tires are cold to get an accurate reading. The 100–120 psi range is a practical, safe operating window for many heavy-duty tires under typical loads.

Maintaining proper tire pressure is essential for handling, tire life, and safety, especially on fire apparatus with heavy loads. The operating range of 100 to 120 psi is appropriate for many heavy-duty tires during regular driving because it keeps the tire under enough load to maintain a stable contact patch with the road and to support the vehicle’s weight. If pressure is too low, the tire flexes more, overheats, wears unevenly, reduces handling, and increases the risk of a blowout. If pressure is too high, the contact patch becomes too small, reducing traction and braking grip, making the ride harsher, and causing excessive center-tread wear. Always follow the tire sidewall and vehicle placard specifications, and check pressures when tires are cold to get an accurate reading. The 100–120 psi range is a practical, safe operating window for many heavy-duty tires under typical loads.