A tire technician is called to a job site where a large front-end loader has a visibly underinflated tire. The site supervisor reports that the machine has been operating at full load for the past two hours. The technician measures the tire pressure and finds it to be 480 kPa (70 psi), while the cold inflation pressure specification is 620 kPa (90 psi). What procedure should the technician follow to safely re-inflate the tire?

Question: A tire technician is called to a job site where a large front-end loader has a visibly underinflated tire. The site supervisor reports that the machine has been operating at full load for the past two hours. The technician measures the tire pressure and finds it to be 480 kPa (70 psi), while the cold inflation pressure specification is 620 kPa (90 psi). What procedure should the technician follow to safely re-inflate the tire?

Answer options:

• Immediately inflate the tire to 620 kPa (90 psi) while it's still hot to account for thermal expansion.
• Inflate the tire to 620 kPa (90 psi) and then bleed off air if it exceeds this pressure after cooling. ✅ Take the machine out of service, allow the tire to cool completely, then inflate to the specified 620 kPa (90 psi) cold pressure.
• Inflate the tire to 550 kPa (80 psi) as an interim measure and monitor for further pressure drop.

Correct answer: Take the machine out of service, allow the tire to cool completely, then inflate to the specified 620 kPa (90 psi) cold pressure.

Explanation: If a tire is significantly underinflated and has been operating under load, it has generated excessive heat. Inflating it while hot to the cold-specified pressure can lead to dangerous overinflation once the tire cools. The safest procedure is to take the machine out of service, allow the tire to cool to ambient temperature, and then inflate it to the correct cold pressure.