Vehicles set with correct geometry will provide:
(1) Less driving fatigue.
(2) Adequate driving safety’
(3) Satisfactory tyre life,
(4) Good service life of other components of the vehicle, leading to an
overall economy and less down time for the vehicle.
However, after the adjustments have been made, it is wise to interchange tyres which will equalize the future normal wear.
The wheels on the same axle are closer together in the front than they are in the This is called as Toe-in. If the Toe-in is excessive, the tyre wear shows featured edges on the inside edges of the skid design, usually more pronounced on the right side.
The wheels on the same axle are closer together in the rear than they are in the front. This is called as Toe-out. Tyre wear shows featured edges on the outside edge of the skid design. Usually it is more pronounced on the left wheel.
Camber angle is the tilt of the wheel, If the wheels are closer to each other at the point of road contact, it is called as positive camber. If the wheels are closer to each other at the top, it is called as negative camber. Excessive camber results in severe wear on any one side of the tyre tread.
Caster angle is the backward tilt oi the axle, or inclination of the king pin at the top, which makes the wheels draw and adjust themselves automatically, depending on the direction of the track, Incorrect caster causes the wheel to be pulled to one side, resulting in severe scuffing and irregular tread wear.King Pin Inclination:
King pin inclination is the angle of the steering axis, relative to the road surface. It stabilizes the wheel at the neutral position and assists in a self- centering action to be generated.
Toe-out on turns refers to the difference in wheel lock between the inner and the outer wheels of a steering axle. An excessive difference will increase tyre wear on front axle, usually move tyre only.
Brakes out of adjustment and out of round brake drums (over-shape) cause tyre tread to wear rapidly specially in a single spot. Improperly adjusted
brakes produce several worn places on
Other Mechanical Irregularities
(a) Bent axle shaft.
(b) Pitted king pin.
(C) Loose steering/Wheel shake.
(d) Loose steering connections like tie rod and drag links.
(e) Improperly adjusted, hard/weak suspension’
(f) Loose or missing wheel studs and nuts.
(g) Loose U-clamps.
These may have direct or indirect effects on the steering geometry of the vehicle and are likely to cause uneven or fast tread wear.
Every Tyre has a Date to Change for Retreading
Driving on worn smooth tyres could be both dangerous and distractive. Because, a smooth tyre has no grip whatsoever on any type of road surface and Skidding would inevitably result. However hard the brakes
are applied, the vehicle would tend to slip. Moreover, a worn smooth tyre has a very thin layer of rubber remaining which provides less protection for the casing and at this stage the tyres cannot withstand cuts and impact. Most of the tyre casings are rendered unfit for retreading by attempting to run further on smooth tyres. Hence tyres should be removed for retreading when they are worn smooth. Watch the tyres to reach this stage. The timely change for retread, prevents unnecessary purchase of a new tyre.
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