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Tire Width

Is the width of the tire measured in millimeters from sidewall to sidewall. The first three-digit number in the tire size refers to the tire width. For instance, in a size P215/65 R15 tire, the width is 215 millimeters.

Aspect Ratio

Is the ratio of the height of the tire’s cross-section to its width. The two-digit number after the slash mark in a tire size is the aspect ratio. For example, in a size P215/65 R15 tire, the 65 means that the height is equal to 65% of the tire’s width. The bigger the aspect ratio, the bigger the tire’s sidewall will be.

Construction

The letter “R” in a tire size stands for Radial, which means the layers run radially across the tire.

Wheel Diameter

Is the size of the wheel measured from one end to the other. It tells us the size of the wheel that the tire is intended to fit. A size P215/65 R15 tire is made for a wheel with a 15″ diameter.

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

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

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. Thoroughly 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.

Tire air pressure decreases naturally (little by little). It is generally accepted that air pressure in tires on a passenger car decreases by 5–10% (1–2Psi) every month.

Finding Proper tire Pressure

There are a few different places listed below to find your recommended proper tire pressure around your vehicle.

• Vehicle’s Owner’s Manual
• Driver’s Side Door Jamb Placard
• Gas Tank Placard

• 4/32″ or deeper

  Good

• 3/32″

  Replace Tires Soonood

•  2/32″ or less

  Replace Tires Now

The Penny Test

Insert a penny into your tire’s tread groove with Lincoln’s head upside down and facing you. If you can see all of Lincoln’s head, your tread depth is less than 2/32 inch and it’s time to replace your tires.

The Quarter Test

Insert a quarter into your tread groove. If the tread touches Washington’s head, you have at least 4/32 inch of tread remaining.

Tire Tread Wear Bar Indicator

look at the treadwear indicator bar that’s molded into most tires. The bars are located at the bottom of the tread grooves in several locations around the tire. When these bars become visibly flush with the adjacent ribs the tire has no more than 2/32″ of tread remaining. This is a visible indication for when you should replace your tires.