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Horizontal stacking limits for tire storage

Aviation Mechanic Airframe (AMA) practice question 11 of 17 on Landing Gear Systems. ACS element AM.II.E.K9 · difficulty: applied. Want to answer it in a timed quiz? Use the Aviation Mechanic Airframe (AMA) practice mode.

Question bank updated 2026-09-22

QUESTIONAircraft tires 44 inches in diameter must be stacked horizontally for a short period. What is the maximum stack height and storage time?

  1. AThree, and for no more than 12 months
  2. BFour, and for no more than 6 months
  3. CThree, and for no more than 6 months
Show the answer and explanation

Correct answer: C. Three, and for no more than 6 months

  • A — incorrect The stack height is right but the time is not; horizontal stacking must never exceed 6 months.
  • B — incorrect Four high applies only to tires less than 40 inches in diameter, and a 44-inch tire is above that dividing line.
  • C — correct Tires larger than 40 inches in diameter are stacked no higher than three, and aircraft tires are never stacked horizontally for more than 6 months.

BACKGROUND

Aircraft tires should always be stored vertically, resting on the treaded surface, ideally on a rack with a minimum 3 to 4 inch flat resting surface for the tread so the tire is not distorted. Horizontal stacking is not recommended because the weight of the upper tires distorts the lower ones, which can make the bead hard to seat when mounting tubeless tires and opens the rib grooves to ozone attack. If horizontal stacking is necessary it must be short-term, never more than 6 months, and limited to four tires high for tires under 40 inches in diameter or three tires high for larger tires. The ideal storage location is cool, dry, and dark, free of air currents and dirt, with a general safe range between 32 °F and 104 °F. Mounted inflated tires may be stored with up to 25 percent less than operating pressure to reduce ozone vulnerability.

STUDY TIP

Remember the 40-inch dividing line with the stack numbers four and three, and attach the flat 6-month limit to any horizontal stack.

KEY POINTS

  • Tires should be stored vertically on the tread, not stacked flat.
  • Horizontal stacks: four high under 40 inches, three high over 40 inches.
  • Never stack aircraft tires horizontally for more than 6 months.

SOURCES

  • FAA-H-8083-31B ch13 "Tire Storage"
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MORE ON LANDING GEAR SYSTEMS

SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-31B Aviation Maintenance Technician Handbook – Airframe, and 14 CFR part 43. Regulations and handbooks are revised; confirm details against the current edition.