SEQUENCE OF WORKS
1. Rotate each wheel one revolution. Carefully remove stones and other foreign objects from the tread. If a splinter or nail is lodged in the tire, the tire carcass may be damaged. If the tire does not bleed air, have the wheel checked by a specialist.
Fig. 13.37. Carcass crack visible from the inside of the tire
2. Pay attention to abnormalities such as punctures, cuts, cracks or torn sections of the profile. If the defect is discovered after a long period of time, the tire carcass may be seriously damaged by prolonged driving with low tire pressure (Fig. 13.37). If moisture penetrates the puncture and reaches the metal cord, it may be seriously weakened by corrosion.
3. The tread profile of the tires should protrude at least 1.6 mm above the tire surface. The thickness of the profile can be determined by various signs. Wherever there are letters "TWI" (tread wear indicator) on the sidewall of the tire, the tire grooves form a height of 1.6 mm with transverse stripes. As soon as the transverse stripes are level with the working surface, the tire must be replaced, since the car's behavior worsens with a decrease in the tread profile of the tires, especially in wet weather. Replace summer tires with new ones when the tread height is at least 2.0 mm. Winter tires must be replaced when the tread height is about 4.5 mm.
4. Check that all tires are worn evenly.
5. Carefully inspect the sidewalls of the tires. Bulges indicate damage to the carcass.
TECHNICAL DICTIONARY
Wheel balancing
Balanced wheels are installed on the car. During the operation of the car, under the influence of various reasons, the wheel balance may be disturbed, which manifests itself in vibration of the steering wheel.
Wheel imbalance leads to increased wear of steering components, tires and vehicle suspension, so when it occurs, the wheels should be rebalanced. Steering wheel vibration from wheel imbalance occurs in a certain speed range and disappears when the speed decreases or increases. In addition, wheel balancing is necessary after mounting a new tire and after each repair.
Static wheel imbalance
Fig. 13.38. Directions of wheel movement with static (A) and dynamic (B) imbalance
(Fig. 13.38, A) is manifested in the fact that the masses of individual parts of the wheel relative to the axle are different. In this case, if the wheel is mounted on a freely rotating axle, it will turn so that the heavier part of the wheel will always be at the bottom. A wheel with static imbalance can bounce when the car is moving, which will lead to rapid wear of the shock absorber.
Dynamic wheel imbalance
(Fig. 13.38, B) is determined only with rapid rotation of the wheel. The heavier section of the wheel is located to the side relative to the middle section of the wheel and when the wheel rotates, it causes it to swing, which causes accelerated failure of the hub bearing and suspension elements.
TECHNICAL DICTIONARY
Tire wear
Wear on the outside of the front tires indicates that you are going through curved sections of the road at high speeds. In this case, to prevent further wear of the tires, turn the tires over on the rims or swap the front and rear wheels.
The wear on the outer edges of the tire is greater than that of the central part of the cross section indicates that the vehicle has been operated for a long time with too low tire pressure.
Fig. 13.39. One-sided wear of the tire tread. Incorrect wheel alignment angles not only cause increased tire wear, especially one-sided wear, but also contribute to reduced traffic safety
One-sided wear of the tire cross-section indicates incorrect wheel alignment, especially when only one tire has such wear (Fig. 13.39).
Fig. 13.40. Severe wear in the middle of the tire tread profile. Occurs due to frequent vehicle movement at maximum speed, as a result of which, due to the action of centrifugal forces, the tire tread becomes convex in the center and wears out intensively. This type of wear is especially characteristic of the rear wheels (with increased pressure in them)
Increased wear in the middle of the cross section occurs when the vehicle is moving at high speed, at which point the central part of the tread bends outward under the action of centrifugal force. This effect is particularly noticeable on the rear wheels. This wear may also indicate high tire pressure (Fig. 13.40).
Uniform local wear in the cross section indicates a faulty shock absorber.
Uneven wear only in certain areas appears when the wheel is out of balance or the tire frame is damaged.
Fig. 13.41. Place of tire wear as a result of braking with wheel locking of a car without ABS
Severe wear of a single spot in the cross section occurs due to braking with wheel locking of vehicles without anti-lock braking system (Fig. 13.41).
PRACTICAL TIPS
Tire storage
After replacing summer or winter tires, you need to ensure that they are stored properly. A dry, cool, and dark room is best for this. Keep gasoline, oil, and other chemicals away from tires, as their vapors, even in small quantities, can destroy rubber without you noticing.
First, mark the direction of rotation and position of the tires with chalk: VR (PP) - front right, VL (PL) - front left, HR (ZP) - rear right, HL (ZL) - rear left.
Remove the tires, wash with water and dry thoroughly. Clean the tread grooves from all foreign objects.
Stack the wheels on top of each other, preferably on an old pallet.
Store tires without rims in an upright position, turning them from time to time.
This article was borrowed from the website fordbook.ru