ASVAB (Armed Services Vocational Aptitude Battery)Auto and Shop Information (AS)Easy
A mechanic is checking the tire pressure on a vehicle. The recommended cold inflation pressure is 32 PSI. After driving for 30 minutes, the mechanic measures the pressure as 35 PSI. What is the most appropriate action to take?
- ADrive the vehicle for another 30 minutes and recheck.
- BAdd air to reach 37 PSI, accounting for the warm tire.
- CReduce the tire pressure to 32 PSI immediately.
- DLeave the tire pressure as is, as it's within normal operating increase.
Show answer & explanationAnswer & explanation
Correct answer: D. Leave the tire pressure as is, as it's within normal operating increase.
Tire pressure increases as tires heat up during driving. A 3 PSI increase from cold inflation pressure after 30 minutes of driving is normal and does not require adjustment.
Why the other options are wrong
- A. Driving longer would likely increase the pressure further, but the initial reading is already within normal heated operation parameters.
- B. Adding more air would overinflate the tire, which can cause uneven wear and reduced traction.
- C. Reducing pressure when the tire is warm can lead to underinflation once it cools down, which is unsafe.
Cold Tire Pressure
The tire pressure measured when the vehicle has been stationary for at least three hours or has not been driven for more than a mile.
- Always check tire pressure when tires are cold.
- Warm tires will show a higher pressure reading.
- Adjust pressure to manufacturer's cold PSI specification.
Memory trick: Cold tires tell the true story, warm ones rise like a hot air balloon.