TM 9-2610-200-14 2-12 EXCESSIVE TOE-OUT EXCESSIVE TOE-IN CHAPTER 2. CARE, MAINTENANCE, AND INSPECTION (Con't) SECTION I. GENERAL INFORMATION (Con't) 2-18. TIRE WEAR PATTERNS (Con't). a. AIR PRESSURE (Con't) (1) Underinflation. An underinflated tire does not contain enough air for its size and the load it must carry. It flexes excessively in all directions and gets hot. In time, the heat weakens the cords in the tire and may cause a blowout. Underinflation also causes tread edges to scuff the road, which puts uneven wear on the tread and shortens tire life. Never run a flat or nearly flat tire unless the tactical situation in combat requires it. When run for even a short distance or almost flat for long distances, the tire may be ruined beyond repair. (2) Overinflation. Overinflation also causes tire failure. Excessive pressure prevents the tire from flexing enough and causes it to be constantly subjected to hard jolts. When an overinflated tire hits a stone or rut, the cords may snap, causing a break in the cord body. The center of the tread wears more rapidly and does not permit equal wear across the entire tread. Hard riding from too much air pressure also increases wear. (3) Deflation. Tires should never be deflated during or immediately after vehicle operation for the purpose of air pressure adjustment. Tires heat as they roll, causing air to expand, which increases pressure. When the tire cools after pressure adjustment it becomes dangerously underinflated. Pressure increases of more than 20 psi (138 kPa) could indicate underinflation, overloading, or excessive speed. b. MISALIGNED WHEELS. (1) Improper Camber Angle. An improperly adjusted camber angle will cause tires to wear. Improper camber angle means that the wheel assembly is leaning in or out at the top. This causes the tread area to contact the road harder on one side than on the other. causing that side of the tread area to wear unevenly and rapidly. (2) Excessive Toe-in. Excessive toe-in will cause a tire tread to wear. Feathered edges will develop in the inner edges of the tread design. In extreme cases the feathered edges may also appear on the inner edge of the tread area. (3) Excessive Toe-out. Excessive toe- out will cause a tire tread to wear as indicated. Feathered edges will develop on the outer edges of the tread design. In extreme cases the feathered edges may also appear on the outer edges of the tread area. UNDERINFLATION OVERINFLATION
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