Tread wear indicator
Tire tread wear indicators are patterned ridges 1.6mm (0.0630in.) to 1.8mm (0.0709in.) higher than the rest of the tread surface, and are molded into the tread at four to six points along the circumference of the tire. As the tire tread wears in time, the depth of the ridges becomes less until they become flush with the surface of the tread. Tire tread wear indicators indicate the allowable limit of tire wear, showing when it is time to replace the tire. (3/5)
Unusual wear of a Tire
(1) Wear on tire shoulders or center If the tire inflation pressure is too low, the shoulders wear more faster than the center. Overloading produces the same effect. If the inflation pressure is too high, the center wear more faster than the shoulders.
(2) Inside or outside wear Cornering wear, shown in the left, is caused by cornering at excessive speeds. Deformation or excessive play in the suspension parts affects front wheel alignment, causing abnormal tire wear. If one side of the tire tread wears faster than the other, the main cause is probably incorrect camber.
(3) Toe-in or toe-out wear (Feathered wear) The main cause of feathered wear on the tire tread is defective toe-in adjustment. Excessive toe-in forces the tires to slip outwards and drags the tread’s contact surface inwards on the road surface, producing toe-in wear. The surface takes on a distinctive feather-like shape – shown in the illustration – that can be identified by running a finger across the tread from the inside to the outside of the tire. Excessive toe-out, on the other hand, producing the toe-out wear shown in the illustration.
(4) Toe-and-heel wear Toe-and-heel wear is partial wear that often appears on tires with lug and block tread patterns. Tires with a rib tread pattern wear to form wavelike patterns. Toe-and-heel wear tends to occur more easily when the tire is rotating and not being subjected to driving force or braking force. Therefore, toe-and-heel wear occurs most often in non-drive wheels that are not subjected to driving force. In the case of drive wheels, driving force causes tire wear in the direction opposite that of toe-and-heel wear. Braking force also produces similar results. As a result, there is normally little toe-and-heel wear in tires on drive wheels.
(5) Spot wear (Cupping) If the wheel bearings, ball joints, tie rod ends, etc. have excessive play, or if the spindle is bent, the tire will wobble at specific, points in its rotation at high speeds, applying strong friction of causing slippage, both of which lead to spot wear. A deformed or irregularly worn brake drum causes the brakes to be applied at regular intervals, leading to spot wear over a relatively wide area in the circumferential direction. HINT: A canvas patch applied to the tire tread to repair a puncture or a protrusion produced by separation will also lead to spot wear. Sudden starting, braking, and cornering may also lead to spot wear. An excessively unbalanced wheel assembly causes spot wear as well. (4/5)
5. Tire rotation
Because the load which is applied to the front and rear tires are different, and the level of wear also varies. Therefore tires should be rotated regularly so that they will wear uniformly. Tires which the rotational direction is determined must not be replaced at right and left. Tire which the tire size of front and rear are different must not be replaced at front and rear. As the recommended tire rotation method varies depending on model and region, refer to the Owner’s Manual.