When the steering wheel vibrates and the tire has partial wear and tear, it could be caused by problems with the wheel alignment. When the car is first shipped, the wheels are well aligned, but can shift as you drive it. At this time, the process of realigning the wheel is called wheel alignment. 
This is especially important when the wheel or tire is raised up or when the car is lowered through system suspension tuning. Moreover, it is good to realign or check the wheel alignment when purchasing a used car. 
The effect of wheel alignment ranges from fuel saving, longer tire life, safety and comfort, prevention of vibration and shifting of steering wheel, longer life of suspension parts and parts related to maneuvering control. 
There may be cases when you do not encounter any issues for a long period of time. But if you drive frequently on roads where the road condition is not good or have had a big impact, it can shift in one day. It is recommended to align the wheel every 20,000 km for maintenance and prevention. 

 Limit of tire wear and braking distance The braking distance depends on the speed of the car, the load, the slope of the road, wind, brake condition, the time between the point of stepping on the brake and the brake working (the time the car runs until the brake starts working), etc. 

Tire wear is also another important factor in deciding the braking distance. The tire wear is measured by the depth of the tread that does the surface, and when the tire reaches the wear index, the depth becomes 1.6 mm. The tire that reaches the wear index must be immediately replaced because if it is continuously used, the braking distance will be longer, thus it will be easier to slip and the tire can easily be damaged because of an alien substance that penetrates or an external impact that causes hydroplaning. This will make it difficult to brake and operate the steering wheel. 
Tire rotation even with the degree of tire wear, and the difference between front and rear tire wear also greatly affect the handling and safety of the car. Generally, because the engine and the driver seat are located in the front side of the car, the front tires typically get more load than the rear tires. Because the front tire creates friction with the road surface when stopping or starting (front wheel drive), the front tires are worn faster than rear ones. Also, because the front wheels are tilted inside due to the camber angle, it puts more load on the outer side of the tire rather than the inner side. However, the rear tires change the contact force of the inner and outer, depending on the surface of the road.

Therefore, it is necessary to rotate the tire locations periodically so that the weight of the tires ­—the inner and outer sides of the front and rear wheels— will be averaged to form a balance of wear. Appropriate tire rotation can also increase the life of the tires. If you periodically rotate the tires, not only can you check the abnormal wear and damage on the tires, but also effectively manage the tires.  

The left/right asymmetric tires refer to the tires with different left and right shape, which are designed to maintain optimal performance on the contacting surface by analyzing each function dynamically including the control stability, water drainage, braking force, riding comfort etc. This is usually applied to the UHP (Ultra High Performance) tire with maximized high speed handling and recently it has been widely applied to the crossover RV. 

1) The outer part must face the outer side during installation.Because the left/right asymmetric tire has a different shape (pattern) and function (inner – comfort/outer – handling) for the left and right tire, based on the center of the tire, you must install the tire sidewall marked "OUTSIDE" to the outer side for correct driving performance.

2) Unlike the V shape pattern (directional), the driving direction is not limited to one direction. For example, if one tire has been worn out partially due to poor alignment, you can just exchange the location of the opposite side or front and rear. As long as the part marked OUTSIDE is installed on the outer side, it is designed to perform whichever direction it is installed. 

3) The spear tire is convenient.The V shape pattern has a disadvantage of having to carry up to two spare tires, depending on the connection location with the wheel, but for the left/right asymmetric tire, you only need to align the OUTSIDE part to the outer side and can carry less spare tires. 

These are the speed level symbols showing the maximum safe speed of the tire.

When you look at the sidewall of the tire, it has various symbols for load index and rim diameter (inch), tire structure, aspect ratio, cross sectional width etc.

For example, if it is marked P245/45R18 102Y for a tire, P stands for Passenger, 245 for cross sectional width (W) contacting the road surface, 45 for aspect ratio (it is typically called series and means the rate of height to width of the tire),R for radial tire, 18 for internal diameter of the tire (rim diameter), 102 for load index (maximum load index one set of tire can stand), and Y for maximum safety speed.

Maximum safety speed refers to the maximum speed the tire can run within the safe range. It is marked with an alphabet. The speed symbol is ranges from A–Y. The higher the alphabet, the higher the speed, which also refers to a higher performance tire. For the passenger car, it may differ by the car type but generally, the grades Q to Y are assigned. 

The speed level of H means 210 km/h orbelow and W means 270 km/h or below

This refers to the phenomenon of gliding on the water as if riding a water ski. 
The tread, which is the contacting surface of the tire, has grooves that are designed to make the water flow between them. When driving in the rain, the tire rotates on the surface to push the water away, and when the tire is rotating in high speed, it reduces the function of draining the water using the grooves to form a hydroplaning effect between the tire and the surface of the road. The pressure of the water under the tire and the gravity acting on the tire removes the contact to make it glide on the water like a water ski. At this time, it is not rolling on the road but gliding on the water. This phenomenon is called hydroplaning. 
Hydroplaning occurs severely when the tire is worn out, or the air pressure of the tire is not adequate. It is good to replace the tires with depth of less than 1.6 mm. 

This refers to the waving phenomenon that occurs during high speed driving.
When the car is driving on the road, the contacting surface is not an arc but a straight line. But because the tire has a strong elasticity, it recovers as soon as it gets off from the contacting surface. 
When the tire rotates at a high speed before the deformation from the contact with the surface of the road recovers the next deformation occurs, making a wave shape to be buoyed. When this vibration becomes the same frequency as the rotating speed, the wave seems like it is still. This is called the standing wave phenomenon. 

 Because the appropriate air pressure level differs by the car, please refer to the owner"s manual. 

When you look at the side part of the tire, you can see the following symbols 
DOT H2 A7 YHB 3203 
If you read the numbers part of the code, you can identify the manufactured date. 

* 03: Manufactured year. 2003 
* 32: Manufactured week. 32 weeks.  

fIt is the tire of the future that you can safely drive when the tire is flat.

The future car will be equipped with state of the art IT functions and we can easily imagine that it will be a much safer car. There is some good news for the people who dream of cars flying in the sky, swimming in the water and drivingeven with the gun shot to the tire as can be seen in the 007 movies. At least the dream is becoming reality for the tire.

Recently the UHP (Ultra High Performance) tires with increased safety at high speed are gaining explosive popularity. Now the tire exceeds the safety of the UHP tire in normal conditions and the run-flat tire will be the future tire to succeed the UHP.

The basic concept of the run-flat tire is that it can drive at maximum speed of 80km/h for an hour even with a flat tire.

A flat tire was directly linked to an accident in the past and usually the driver had to stop or if not, it caused damage to the expensive wheel and other suspension. The run-flat tire is a great tire for drivers who drive long distances frequently, who cannot replace the spare tire or who are female drivers. 

The winter tire maximizes the contacting force and the towing ability on snowy or icy roads through tread rubber and pattern design.

By inserting Kerf inside the tread block, the winter tire maximizes the contact surface. But the summer tire uses the new material, silica rubber to optimize the towing power by maintains the flexibility in the low temperature unlike normal rubber.

The winter tire can be classified into the tires with the spikes to increase the towing ability and friction and the studless tire utilizing the simple tread rubber material and pattern design. Of course, the tires with the spikes show better performance but as you deviate from the snow road, the riding comfort and noise performance is disadvantage in the snow.