KUMHO TIRE Global Network
Importance in safety control of tire is always emphasized but thing that it is not easy to carry out is replacement of tire position. For front wheel rolling(FF) type of car, wear rate of the front tire is more rapid than rear tire by about 15 through 20% and so car can exert proper function of a tire when replacing position of front tire with that of rear tire when the car travels over 10,000 km without replacement.
For front wheel rolling (FF) type of car, wear rate of the front wheel is more rapid than rear wheel by about 15 through 20% and so replacement of position is done to extend life of a tire by evenly wearing out 4 wheel and preventing partial wear of the tire. Wear of a tire occurs because of movementof pattern blocks on the grounding surface of a tire traveling. In this time, weight applied to the ground surface has also a great effect on wear index. The size of wear can be described as grounding pressure and friction energy by slip. Wear largely differs depending on mounting position of a tire together with tire inflation pressure, travelingspeed, use condition, road condition and status of car. Wear is classified into rapid wear that life of a tire significantly becomes short and irregular wear that is worn out severely by various factors.
Of them, replacement of tire position is management method to reduce rapid wear. For a tire mounted on the front wheel rolling type of car, wear rate of the rear wheel is only 70 through 80% in comparison with thefront wheel. As mentioned before, wear depending on mounting position of engine and position of driver's seat is caused because grounding pressure of the front wheel is significantly higher than the rear wheel.
Generally for a passenger car, it is known that it is good to change position of front/rear tire after traveling by 5,000 ~ 10,000 km. However, since such traveling mileage largely changes depending on various conditions including driver's driving habit or road status, it is good to determine position replacement time after checking wear status of front tire for the front wheel rolling type of car, and of rear tire for the rear wheel rolling type of car. Generally wear limit of a tire is 1.6mm and a tire for winter season must be replaced since performance is reduced if depth of the groove is worn out by 1/2.
Wear limit is concavely indicated with height of 1.6mm in a groove of the tread that the angular point of a triangle indicated in the side surface of tire points out. If even this part is worn out, you must replace with a new tire. A tire whose groove depth is below 1.6mm is prohibited according to Automobile Management Act and constitutes rejection factor in automobile inspection. Even though wear limit is beyond 1.6mm, if there is a tire whose either side is worn out specially much or worn out while forming a layer, it is good to replace the tire or replace position of tire position.
Method to replace tire position differs depending on position of the driving axle. For the front wheel rolling type of car, move the front wheel backward without changing the left side and the right side and replace the only rear wheel in cross of the left and the right. For the rear wheel rolling type of car, replace the front wheel and the rear wheel in cross each other and move the rear wheel forward without changing the left side and the right rear and replace the only front wheel with the rear wheel.However, for directional tread pattern of UHP (Ultra High Performance) tires, replace only front and rear position without changing the left side and the right side. Extra Supra, Exta DX, Exta MX, Exta SPT of Marshal Tire's products are included in this category.