Tire Class - "P" The first character(s) in a tire size designate the tire's class. In this example, "P" indicates that the tire is a passenger car tire. An "LT" before the tire size designates a light truck tire, and no letter before the size indicates that it is a European metric tire.
Section Width - "185" A metric tire's section width is measured in millimeters. This measurement is taken from sidewall to sidewall.
Aspect Ratio - "75" This number refers to the height of the sidewall. It is a percentage of the section width.
Tire Construction - "R" The "R" in this example indicates radial tire construction.
Wheel Diameter - "14" This indicates the wheel diameter in inches.
Load Rating - "82" The load index indicates the maximum amount of weight a tire can safely carry. Load index ranges from 0 to 279 and corresponds with the load-carrying capacity of a tire. Passenger car tire load indices typically range from 75 to 105. It is very important to maintain the proper load index for your vehicle when replacing your tires.
Speed Rating - "S" A tire receives its speed rating from the U.S. Government by meeting minimum standards for reaching and sustaining a specified speed. In general, a higher speed rating will result in better vehicle handling.
On newer cars, the recommended pressure is most commonly listed on a sticker inside the driver’s door. If there’s no sticker on the door, you can usually find the specs in the owner’s manual.
Do not inflate your tires to the pressure listed on the tire itself. That number is the maximum pressure the tire can hold, not the recommended pressure for the vehicle. Tricky, huh?
For safety and maximum tire life, check the air pressure in your tires at least once a month. Use an accurate tire pressure gauge. Don’t guess and fill your tires by the way they look.
The best protection against blowouts is to properly inflate your tires. Don’t let them get too soft; don’t overinflate them. Also, make sure you select a tire that is designed for your driving conditions.
Check your tire pressure regularly, rotate your tires, and watch for signs of uneven wear, which can mean alignment problems.
When your tread wears down to 4/32 of an inch you start to lose significant traction on wet or snowy roads. A Washington quarter, placed upside down in the tread grooves at several points, is a handy gauge. You’re o.k. if the tread covers part of Washington’s head. To meet safety requirements in most states tires must pass the Lincoln penny test, a minimum tread depth of 2/32 inch. Manufacturer’s also place wear bars in the grooves between tire treads. When the tread is nearly flush with the bars, it’s time to replace your tires.
On wet pavement, the tread grooves sluice water away from the tire where it makes contact with the road. A typical new passenger tire has a tread depth of 10/32 of an inch. When tread wears to even half that depth, the risk increases that your car will hydroplane—slide on the surface of standing water—especially at highway speeds. On snowy pavement, horizontal treads and small slits in the rubber called “sipes” bite into the snow. The deeper the tread, the better the grip.
For a smooth ride, tires must be balanced properly. Also, some tires ride better than others. When buying a tire there is always a compromise, tires with a long tread life have a harder ride and tires with a softer ride wear faster. It is best to consult a tire expert to determine the best tire for common road conditions and the way you drive.
Possibly. A very soft tire (under inflated) can cause your car to pull to one side or the other. This could also be and issue with your alignment, either reason, this is a very unsafe situation, under these conditions you should get this checked immediately.
Only punctures in the center treads are repairable. This is should be evaluatated by a professionals.
You can improve fuel economy by up to 5% by keeping you tires inflated to the correct pressure.