Tire Tips

Find this information and more at:

P. A. R. T.

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  • Oil Change

    Pressure

    Underinflation results in unnecessary tire stress, irregular wear, loss of control and accidents. A tire can lose up to half of it's air pressure and not appear to be flat. Overinflation can also result in premature tire wear.

  • Oil Change

    Alignment

    A bad jolt from hitting a curb or pothole can throw your front end out of alignment and damage your tires. Normal wear-and-tear over time will also effect your alignment. Have your alignment checked periodically (yearly) to ensure that your car is properly aligned.

  • Oil Change

    Rotation

    Promotes uniform tire wear. Regularly rotating your vehicle's tires will help you achieve more uniform wear. Unless your vehicle owner's manual has a specific recommendation, the guideline for tire rotation is approximately every 5,000 miles (7,500 miles maximum).

  • Oil Change

    Tread

    Measure it -- and inspect it.
    Advanced & unusual wear can reduce the ability of tread to grip the road in adverse conditions. Visually check your tires for uneven wear, looking for high & low areas or unusually smooth areas. Also check for signs of damage.

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How to Read a Tire's Sidewall

1. Manufacturer's name and/or Logo

2. Tire's name/style

3. Tire Size


Example:

P205/60R15



P

- Passenger --or--

LT

= Light Truck

ST

= Trailer tire

No letter

= European metric (similar to 'passenger')

205

= The width of the tire in millimeters

60

= The ratio of heighth to width

R

= Radial (B or D = Bias Ply)

15

= The nominal rim diameter

4. Service Description


Example:

90S



90

= The Load Index (See Max Load [#6] for actual weight capacity)

S

= The Speed Rating

5. UTQG Ratings


Example:

Treadwear 620 Traction A Temperature B


Treadwear, traction and temperature grades.

The treadwear grade is a comparative rating based on the wear rate of the tire when tested under controlled conditions on a specified government test track. A tire graded 200 would wear twice as long on the government test track as one graded 100 (Actual tire mileage may vary). Note: treadwear grade is only for comparisons within a manufacturer's product line, not between manufacturers. For example, a 700 rating from one tire manufacturer is not necessarily better than a 600 from another.

Traction grades, from highest to lowest, or AA, A, B and C. They represent the tire's ability to stop on wet pavement as measured under controlled conditions on specified government test surfaces of asphalt and concrete. The traction grades are based upon "straight ahead" braking tests. It does not indicate cornering ability or resistance to hydroplaning.

Temperature grades represent the tire's resistance to head generated by running at high speed. Sustained high temperatures can cause the materials of the tire to degenerate and thus reduce the tire life. Excessive temperatures can lead to tire failure. Federal Motor Vehicle Safety Standards require that all passenger tires meet at least the minimal level of performance. A = Best B = Intermediate C = Acceptable

6. Maximum Load and Air Pressure


Example:

Max Load: 590kg (1301 lbs.) at 300kPa (44psi) max pressure



The maximum load a tire can hold is shown in kg (kilograms) and in lbs. (pounds). The maximum air pressure a tire can hold is shown in kPa (kilopascals) and in psi (pounds per square inch). The proper amount of air pressure to have in your tire is determined by the vehicle manufacturer, but never to exceed the maximum pressure as labeled on the tire. You can find this information in your owners manual or on a placard, usually placed on the driver side door.

7. Plies


Example:

Plies: Tread 2 Steel + 1 Polyester + 1 Nylon Sidewall 1 Polyester



Tread: Provides traction and cornering grip

Belts: Stabilize and strengthen the tread

Sidewall: Protects the side of the tire form road and curb damage

Body Ply: Gives the tire strength and flexibility

Bead: Assures an air-tight fit with the wheel

Inner liner: Keeps air inside the tire

8. DOT Number


Example:

DOT T7CH DFAH 2308



The letters "DOT" certify compliance with all applicable safety standards established by the Department of Transportation (DOT). DOT numbers are a maximum of twelve digits. It specifies the company, factory, mold, batch, and date of production. The first two letters (T7) are assigned by the DOT to the manufaturing plant. THe third and fourth letters (CH) represent the tire size. The middle three or four letters (DFAH) are a group of symbols, optional with the manufacturer, to identify the brand or other characteristics of the tire. The last four digits identify the week and the year of manufacture.
(Example: "2308" means the 23rd week of the year 2008.)

Where to mount two new tires

The Right Way

NEW TIRES ON THE REAR

UNDERSTEER


Understeer is the condition where the front tires lose traction before the rear tires, and where the sensation is that the front of the vehicle is "pushing" or "plowing" through a corner. With extreme understeer, the car will leave the road front wheels first.
This condition is considered the safest for the average driver and most OE vehicles have understeer purposely built into their handling characteristics.
The correction for understeer is to reduce speed and steer angle until the front tires regain traction.
The Wrong Way

NEW TIRES ON THE FRONT

OVERSTEER


Oversteer is the condition where the rear tires lose traction before the front tires, giving the sensation that the rear of the vehicle is drifting or sliding. With extreme oversteer, the back end will try to pass the front end, resulting in leaving the road rear wheels first.
This condition is considered favorable by expert performance drivers, but requires more work to control.
The most simple correction for oversteer is to turn the front wheels in the direction of the skid (same correction as for rear end sliding on snow and ice). But there are different causes for oversteer, and different corresponding solutions.