Tire Check-Up
The tires are the feet of a vehicle, supporting the load during running, functioning as cushions, transmitting driving and breaking forces, changing and maintaining the direction. However, any tire can fail if it is used wrongly or if it is not maintained. Failures and damage to tires extend over a wide range of levels, from very slight damage to a total failure that can threaten the safety of the vehicle occupants. Most tire damage and failures can be considered as the results of the incorrect usage and /or mis-management of the tires. Recognising the tire damage adequately and learning the correct tire usage procedures and management methods will contribute to safe driving and a reduction of expense for the users.
Tread
Tread – Center wear
Condition of damage
The center of tread wearing faster than the shoulders
Causes
1. Overinflation
2. Improper matching of tires and rims
3. Tires are not rotated timely
Recommendations
1. Use tires under the recommended air pressure
2. Use proper rims
3. Rotate tires timely before center wear becomes serious.
Examples
Center wear
Tread – Shoulder Wear
Condition of damage
Both shoulders wearing faster than the center tread
Causes
1. Underinflation and / or overload
2. Repeated sharp turns at a high speed in cornering
3. Improper matching of tires and rims
4. Tires are not rotated timely
Recommendations
1. Use tires under the recommended air pressure
2. Avoid rough driving in cornering
3. Use proper rims and mount tires properly
4. Rotate tires timely before shoulder wear becomes serious
Examples
Shoulder wear
Tread – One-sided Wear
Condition of damage
One side of tread wearing unusually fast
Causes
1. improper wheel alignment (especially faulty camber)
3. Overload
4. Frequent use on high crown roads
Recommendations
1. Adjust wheel alignment correctly
2. Rotate tires timely before one-sided wear becomes serious
3. Avoid overload
4. Remount tires conversely
Examples
One-sided wear
Tread – Feather Edge Wear
Condition of damage
The blocks or the ribs of tread wearing in a feather edge pattern
Causes
1. Improper wheel alignment (especially faulty toe-in)
2. Bent axle beam
Recommendations
1. Adjust wheel alignment correctly
2. Adjust mechanical faults correctly
Examples
Feather Edge Wear
Tread – Heel and toe wear
Condition of damage
One side of the blocks and / or lugs on the tread wearing faster than the other side circumferentially like sawteeth
Causes
1. Tires are not rotated timely
2. Underinflation and / or overload
3. Sudden braking or rapid acceleration
Recommendations
1. Rotate tires timely before heel & toe wear becomes serious
2. Use tire under proper air pressure and load
3. Avoid rough driving
Examples
Heel and toe wear
Tread – Spot Wear
Condition of damage
Patches of excessive wear occurring at intervals around the circumference
Causes
1. Faulty suspensions, faulty rotating parts and / or brake parts such as axle beams, bearings and brake shoes
2. Dynamic imbalance of tire and rim assembly
3. Excessive run-out of tire and rim assembly
4. Sudden braking or rapid starting
5. Underinflation and / or overload
Recommendations
1. Avoid rough driving
2. Repair the mechanical parts such as faulty suspension,axle beams, bearing and brake shoes
3. Minimize the run-out of tire and rim assembly by matching the maximum run-out point of tire to minimum run-out point of rim
4. Adjust the dynamic imbalance of tire and rim assembly with a wheel balancer
Examples
Spot wear
Sidewall
Sidewall – Bleeding* CBU(Cord Broken Up) *Inflation pressure will leak gradually
Condition of damage
Carcass cords are broken up circumferentially at shoulder or sidewall in a line or a saw pattern
Causes
Excessive heat generation and fatigue caused by gradual leakage of air due to:
1. Unmatched valve core or aged core rubber
2. Fine materials such as mud or dust in the valve
3. Pin hole (small puncture) or tire and/or tube
4. Rust or any fine materials on the bead seat of rim
5. Unsatisfactory repair of puncture
Recommendations
Stop to use the damaged tire
1. Use tires under the recommended air pressure and load, and check the air pressure periodically
2. Use a correct, new valve core
3. Use a valve cap to avoid entry of fine materials
4. Use new tubes for new tires
5. Remove rust or fine materials from the bead seat of rims when tires are mounted
6. Repair punctured tires and/or tubes correctly.
Examples
Bleeding CBU
Sidewall – CBU Due To Cut Or Shock
Condition of damage
Carcass cords are broken up at shoulder and / or sidewall
Causes
1. Bad distortion or pinching between object and wheel(tire)
2. Hard hit against the object
3. Low inflation pressure
4. Low aspect ratio tire is more likely to get CBU
Recommendations
Stop to use the damaged tire
1. Drive carefully to avoid obstacles. If the obstacles cannot be avoided, reduce the speed
2. Check tires frequently, and remove foreign materials between the duals
3. Use tires under the recommended air pressure and load
Examples
CBU due to cut or shock
Sidewall – Runflat
Condition of damage
Normally, the tire sidewall is severely damaged as in the picture shown on the right. In the case of bias tires(cross-ply tires), the inner carcass cords may separate and may be exposed on the surface
Causes
1. Continuous running after puncture
2. Excessive underinflation(close to a flat condition)
Recommendations
Stop to use the damaged tire
1. Stop the vehicles as soon as a flat tire is aware of, and change the flat tire to spare tire immediately
2. Check air pressure frequently
3. Check any nails imbedded in tread or other external damage frequently
Examples
Runflat
Bead
Bead – Rim cut and injury
Condition of damage
Rim cut and injury
Causes
1. Faulty (deformed, rusted, etc.) rims or wrong size of rims
2. Careless mounting/dismounting (omission of lubricant such as soapy water on bead, mishandling of tir
Examples
Rim cut and injury
Handling
Handling – Vibration
Condition of damage
Car body or steering wheel vibrates vertically or laterally. Such vibrations normally occur at speeds of about 80km/h or more.
Causes
1. Imbalance of tire-rim assembly
2. Excessive run-out of tire-rim assembly
3. Improper mounting of tires on rims
4. Abnormal wear such as spot wear, wavy wear, heel & toe wear, etc
5. Faulty steering parts, joints, shock absorber, etc.
Recommendations
Consult your car/tire dealer
1. Throughly adjust the imbalance of tire-rim assembly
2. Mount tires on rims properly
3. If abnormal wear is found, rotate the tires
4. Repair the mechanical parts such as faulty steering parts, joints, shock absober, etc.
Vibration
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