In 1902 it was reckoned that a light car, driven carefully at not more than 25 mph, might achieve 2000 miles on a set of tires. Fast cars were expected to do less than 1000 miles on a set of tires. Isn't it nice we've made such advances in tire rubber!
Tire pressure affects the load-carrying capacity and overall performance of your vehicle.
Low pressure overheats the tire causing cord/sidewall damage and abnormal wear and Higher pressures cause rough ride and abnormal tire wear.
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:
1. Most tires may naturally lose air over time.
2. Tires can lose air suddenly if you drive over a pothole or other object or if you strike the curb when parking.
3. When the outside temperature drops 10 degrees Fahrenheit, the air pressure inside your tires goes down about one or two psi. If your tires were inflated on an 80 degree day, a 30 degree day could drop the pressure almost 10 pounds! The opposite will occur in warmer weather.
4. With radial tires, it is usually not possible to determine under inflation by visual inspection.
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.
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.
Have the air pressure checked at least every 3,000 miles or 3 months if not sooner.
Have the tires inspected and rotated every 6,000 miles or 8 months (every other oil change).
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.
Whether a tire is old and unsafe cannot always be detected by the naked eye. Tires undergo an aging process even when they are not in use. The rubber loses its elasticity, the steel webbing corrodes and the rubber hardens. A tire that has been in storage for years will look brand new and is extremely dangerous.
Most experts recommend replacing a tire after it reaches 6 years old, even if it hasn't been used, but after 10 years the tire is definitely not safe for higher speeds or loads. More on tire aging.
HOW MANY MILES CAN TIRES GO?
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.
The next factor is how you drive. With very gentle driving you might get the claimed 70,000 miles from your tires. If you drive hard, stop accelerate quickly the same tires might not last 30,000 miles.
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. Snow tires usually come with siping, but they are for winter use only.
ConsumerReports.org did a test on two different tire 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.
HOW IMPORTANT IS NITROGEN IN TIRES?
The biggest advantage of nitrogen is less loss of pressure over time because nitrogen molecules are larger than oxygen, which increases fuel economy. However, according to a year-long study by Consumer Reports in 2006, there was only a 1.3 psi difference in loss between nitrogen and air in 1 year, since both lost pressure, you still need to check air pressure regularly.
Nitrogen has less moisture than regular air, and can help tires run cooler in some circumstances, but today's passenger car tires are designed for the driving most of us do with regular air.
Is it worth it?
The air we breathe is already 78 percent nitrogen, 21 percent oxygen and a few other elements. To get the best benefits from nitrogen for our tires, nitrogen needs to be at least 93 percent pure, which means you only need another 15% nitrogen to get there.
It usually costs $20 - $28 to have the tires filled with nitrogen. When the tires get low you have the choice of finding a place with nitrogen and paying to have them topped off or use regular air which puts oxygen back into the tire.
Unless the nitrogen comes free with the tire installation it is probably not cost effective. Checking the air pressure in your tires every 3 - 4 months is the best option. This should be done even with nitrogen.
ALL SEASON TIRES VERSUS WINTER TIRES
For tires, the "all season" or "mud and snow" 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.
Everything that makes all-season tires effective on dry, warm pavement works against them on snow and ice. Their rigid designs and narrow treads nibble at the snow instead of digging in. When all-season tires begin to wear, their already modest traction in snow is further compromised.
Winter tires are designed the softest rubber compounds available to stay flexible and maintain their grip in freezing weather. More important, their deep treads are densely packed with small crosshatchings called sipes. Like the edge of a ski, the thousands of tiny sipes carve deeply into the snow to deliver traction.
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.
The stability of the tire in cornering, accelerating, braking is not as good on dry ground and in warm weather (in comparison to All-Season tires). Additionally, tire noise/droning is many times noticeable when driving on dry ground. Your gas mileage will also be worse if you leave snow tires on year round.
HOW DO YOU TELL A WINTER/SNOW 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.Mountain Snowflake Tire
Tire manufacturers agreed on a set of criteria in 1999 for dedicated winter/snow tires. All Winter tires should have a Mountain Snowflake symbol on tire sidewalls to ensure they're specifically designed for slick, snowy conditions.
Switching the tires in Spring and Fall is a drawback for Winter tires, but that is the same for studded tires and Winter tires are much easier on the roadway than studded tires.
If you drive a car made after 2007, you have what's called a Tire Pressure Monitoring System (TPMS) installed. TPMS is an electronic system that monitors your tires for low air pressure. TPMS has been required by the NHTSB 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.
There are many different systems used for different cars, which means there is no common diagnostic, service or relearn procedures cover all the systems.
Tire pressure is usually monitored through one of two methods: direct or indirect. Direct TPMS monitors the actual air pressure inside each tire via a sensor mounted within the tire. Indirect TPMS measures tire pressure by monitoring the speed and rotation of each individual wheel. With the indirect system, when a significant variation in speed and rotation is detected in one or more wheels when compared with the others, it is often an indication of underinflation. This information is then transmitted to the vehicle's on-board computer and the light is turned on.
The NHTSA reports that annually there are nearly 200,000 accidents caused by tire-related issues with 660 highway fatalities and 33,000 injuries due to underinflated tires. The NHTSA also estimates that roughly 3.5 million gallons of gasoline are wasted daily due to underinflated tires.
If you add air to a low tire or repair or replace one or more tires, or rotate the tires there may be a reset procedure required.
The TPMS is calibrated for the original equipment wheels and tires, so replacing the wheels with aftermarket parts may cause some problems.
Besides the safety concerns, this will help save on wasted gas from running on low tires, Keep in mind though, gas mileage has already started dropping when the tires are 10% under inflated.