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TIRE INFLATION Tire pressure affects the load-carrying capacity and overall performance of
your vehicle. Manufacturers of passenger vehicles and light trucks determine the proper pressure based on the greatest amount of weight a vehicle can safely carry and the vehicle's tire size. The proper tire pressure for your vehicle is referred to as the "recommended cold inflation pressure." Because tires are designed to be used on more than one type of vehicle, tire manufacturers list the "maximum permissible inflation pressure" on the tire sidewall. This number is the greatest amount of air pressure that should be put in the tire and should not be used for normal driving. To find the proper pressure for your vehicle, look on the driver’s door jamb or the owner’s manual. It is important to check your vehicle's tire pressure at frequently for the following reasons:
The recommended tire inflation pressure that vehicle manufacturers provide reflects the proper psi when a tire is cold. The term cold does not relate to the outside temperature. Rather, a cold tire is one that has not been driven on for at least three hours. When you drive, your tires get warmer, causing the air pressure within them to increase.
TIRE WEAR Tires have built-in tread wear indicators that let you know when it is time to replace your tires. These indicators are raised sections spaced intermittently in the bottom of the tread grooves. When they are even with the outside of the tread, it is time to replace your tires. Another method for checking tread depth is to place a penny in the tread with Lincoln's head upside down and facing you. If you can see the top of Lincoln's head, you are ready for new tires.
TIRE MAINTENANCE Have the air pressure checked at least every 3,000 miles or 3
months if not sooner.
TIRE AGE Tires, like any other rubber product, have a limited service
life regardless of tread depth and use. (Rubber is an elastomer, which
constantly changes its properties due to exposure to air (oxidation), heat
and other environmental factors) As tires age, their physical and chemical
properties degrade reducing their margin of safety. You would think that a tire
should be designed such that the tire fatigue life exceeds the tread life by
some safety margin. But the U.S. tire industry has done very little to warn us
about the risks of old tires.
The greatest factor in tire longevity besides maintenance is the
roads on which you drive. Tire companies have mapped out average tread life by
county and discovered that tread life is inversely proportional to local
elevation. It's great in the flat-lands of west Tennessee and eastern Colorado,
but poor in the Smokies and Rockies. It's also better for those who do most of
their driving on roads with long straights and gentle curves. And it's worse the
farther south you go, due to the heat.
IS TIRE SIPING A GOOD IDEA? The practice of siping, or cutting extra slits into tire treads, is supposed to improve a tire’s snow and ice-biting ability. This does help in snow and ice, but in warm weather the tire may wear much faster. ConsumerReports.org did a test on two different brands, siped and non-siped and found that the siped version of both brands showed modest but measurable improvements in snow-traction and ice-braking performance. But braking distances on wet and dry pavement were a few feet longer.
ALL SEASON TIRES VERSUS WINTER TIRES For tires, the "all season" name alone convinces
people that they're ready for anything from the Sahara to Siberia. But as the
label implies, all-season tires must strike a compromise among factors such as
dry and wet traction, durability, fuel economy and a quiet, comfortable ride.
Because of their flexible sipes and softer rubber
compounds for gripping, winter tires wear out much more quickly than all-season
models when they're used on dry pavement.
HOW DO YOU TELL A WINTER TIRE FROM AN ALL-SEASON? Many all-season tires display an M&S logo, which stands for mud and snow. However, there are no traction standards required to earn the designation. To clear up confusion, tire manufacturers
in 1999 agreed on a set of criteria for dedicated winter tires. Consumers can
now look for the Mountain Snowflake symbol on tire sidewalls to ensure they're
specifically designed for slick, snowy conditions.
Tire Pressure Monitoring Systems
or TPMS has been required since 2008 on all cars and light trucks. These systems
illuminate some type of warning light if tire pressure drops 25% or more below
the recommended inflation pressure. So if a tire is supposed to carry 32 psi,
the low-pressure tire warning light should come on if tire pressure drops to 24
psi or less.
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