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Tire Wear Patterns

HOW TO READ TIRE WEAR

The way your tires wear is a good indicator of other parts of your car. Abnormal wear patterns are often caused by the need for simple tire maintenance, or for front end alignment. Tires should be inspected at every opportunity; once a week isn't too often. Learning to read the early warning signs of trouble can prevent wear that shortens tire life or indicates the need for having other parts of the car serviced. Tires should be inspected 3 ways. First, visually examine all 4 tires; second, feel the tread by hand to detect wear such as feathering and third, check all 4 tires with a pocket type pressure gauge.
Over Inflation Over Inflation
Excessive wear at the center of the tread indicates that the air pressure in the tire is consistently too high. The tire is riding on the center of the tread and wearing it prematurely. Many times, the "eyeball" method of inflation (pumping the tires up until there is no bulge at the bottom) is at fault; tire inflation pressure should always be checked with a reliable tire gauge. Occasionally, this wear pattern can result from outrageously wide tires on narrow rims. The cure for this is to replace either the tires or the wheels.
Under Inflation Under Inflation
This type of wear usually results from consistent under inflation. When a tire is under inflated, there is too much contact with the road by the outer treads, which wear prematurely. Tire pressure should be checked with a reliable pressure gauge. When this type of wear occurs, and the tire pressure is known to be consistently correct, a bent or worn steering component or the need for wheel alignment could be indicated. Bent steering or idler arms cause incorrect toe-in and abnormal handling characteristics on turns.
Feathering Feathering
Feathering is a condition when the edge of each tread rib develops a slightly rounded edge on one side and a sharp edge on the other. By running your hand over the tire, you can usually feel the sharper edges before you'll be able to see them. The most common cause of feathering is incorrect toe-in setting, which can be cured by having It set correctly. Occasionally toe-in will be set correctly and this wear pattern still occurs. This is usually due to deteriorated bushings in the front suspension, causing the wheel alignment to shift as the car moves down the road.
One Side Wear One Side Wear
When an inner or outer rib wears faster than than the rest of the tire, the need for wheel alignment is indicated. There is excessive camber in the front suspension, causing the wheel to lean too much to the inside or outside and putting too much load on one side of the tire. The car may simply need the wheels aligned, but misalignment could be due to sagging springs, worn ball joints, or worn control arm bushings. Because load has a great affect on alignment, be sure the car is loaded the way it's normally driven when you have the wheels aligned; this is particularly important with independent rear suspension cars.
Cupping Cupping
Cups or scalloped dips appearing around the edge of the tread on one side or the other, almost always indicate worn (sometimes bent) suspension parts. Adjustment of wheel alignment alone will seldom cure the problem. Any worn component that connects the wheel to the car (ball joint, wheel bearing, shock absorber, springs, bushings, etc.) can cause this condition. Worn components should be replaced with new ones. The worn tire should be balanced and possibly moved to a different location on the car. Occasionally, wheels that are out of balance will wear like this, but wheel imbalance usually shows up as bald spots between the outside edges and center of the tread.
Second-rib Wear Second-rib Wear
Second-rib wear is normally found only in radial tires, and appears where the steel belts end in relation to the tread. Normally, it can be kept to a minimum by paying careful attention to tire pressure and frequently rotating the tires. Some car and tire manufacturers consider a slight amount of wear at the second rib of a radial tire normal, but that excessive amounts of wear indicate that the tires are too wide for the wheels. Be careful when having oversize tires installed on narrow wheels.

article provided from www.procarcare.com

 

Tire Rotation

Tire rotation or rotating tires is the practice of moving automobile wheels and tires from one position on the car, to another, to ensure even tire wear. Tire wear is uneven for any number of reasons. Even tire wear is desirable to maintain consistent performance in the vehicle.

By design, the weight on the front and rear axles differs which causes uneven wear. With the majority of cars being front-engine cars, the front axle typically bears more of the weight. For rear wheel drive vehicles, the weight distribution between front and back approaches 50:50. Front wheel drive vehicles also have the differential in front, adding to the weight, with a typical weight distribution of no better than 60:40. This means, all else being equal, the front tires wear out at almost twice the rate of the rear wheels, especially when factoring the additional stress that braking puts on the front tires. Thus, tire rotation needs to occur more frequently for front-wheel drive vehicles.

Turning the vehicle will cause uneven tire wear. The outside, front tire is worn disproportionately. Cloverleaf interchanges, and parking ramps turn right in left hand drive (otherwise known as right hand traffic) countries, causing the left front tire to be worn faster than the right front. Furthermore, right turns are tighter than left turns, also causing more tire wear. Conversely the sidewalls on the right tire tends to be bumped and rubbed against the curb while parking the vehicle, causing asymmetric sidewall wear. The symmetric opposite occurs in countries that drive on the left.

In addition, mechanical problems in the vehicle may cause uneven tire wear. The wheels need to be aligned with each other and the vehicle. The wheel that is out of alignment will tend to be dragged along by the other wheels, causing uneven wear in that tire. If the alignment is such that the vehicle tends to turn, the driver will correct by steering against the tendency. In effect the vehicle is constantly turning, causing uneven tire wear. Also, if a tire is under or over-inflated, it will wear differently than the other tires on the vehicle. Rotating will not help in this case and the inflation needs to be corrected.

Car manufacturers will recommend tire rotation frequency and pattern. Depending on the specifics of the vehicle, tire rotation may be recommended every 12,000 km (7,500 mi). The rotation pattern is typically moving the back wheels to the front, and the front to the back, but crossing them when moving to the back. If the tires are unidirectional, the rotation can only be rotated front to back on the same side of the vehicle to preserve the rotational direction of the tires. Most unidirectional tires can be moved from side to side if they are remounted; tires with asymmetric rims are a rare exception. More complex rotation patterns are required if the vehicle has a full-size spare tire that is part of the rotation, or if there are snow tires.

To clarify; the pattern for asymmetrical tires to be rotated, or positioned, is for the tires on the driving axle of two-wheel drive vehicles to remain on the same side of the vehicle as they are moved to the non-driving axle, and for the tires on the non-driving axle to cross over to the opposite side of the vehicle as they are placed onto the driving axle. For All Wheel Drive (AWD) vehicles and Four Wheel Drive (4WD) vehicles, it is recommended that the tires from each axle cross over as the fronts move to the rear and rears to the front. For the 4WD configuration, it is dependent upon how much 4WD driving is actually performed, whether it's controlled via mechanical/computerized devices or in vehicle controls, the recommendation will likely be found in the Owner/Operator manual or can be obtained by speaking to the manufacturer or dealership.

Current thinking stresses the desirability of keeping the best tires on the rear wheels of the vehicle, whether it is front, or rear wheel drive. The reason for this is that if the rear wheels lose grip before the front ones, an oversteer condition will occur, which is harder to control than the corresponding understeer which will happen if a front wheel is lost. This is also the case if a tire blows out, so the intuitive belief that the front steering/driving tires need to be the best quality is not actually the case.

In rare cases, automobile manufacturers may recommend performing no tire rotation at all.

article provided from www.wikipedia.com

Nitrogen Filled Tires
Nitrogen is all around us. When used to replace oxygen and other
gases in tire inflation, it enhances handling, improves fuel
efficiency, extends tire life, protects the Earth and,
most importantly, keeps you safer on the road.
If you are one of the 85% of Americans who
don't regularly check tire pressure, you need
nitrogen.

We take in nitrogen with every breath. Air is composed of:

  • 1% Water Vapor and Other Gases – Escapes up to 250 times faster than Nitrogen
  • 21% Oxygen – Escapes 3-4 times faster than Nitrogen
  • 78% Nitrogen – The largest molecule in
    air, dry, non-flammable.

Because of their large size, nitrogen molecules are the least permeable and stay in your tire longer.

It's not about the nitrogen. It's about reducing oxygen, water vapor and other gases.

By reducing the percentage of oxygen, water vapor and other gases in your tires from 22% to 7% or lower, your tires will maintain proper pressure longer than if you use “plain old air.” For example, with 95% nitrogen in your tires, they retain optimal pressure three to four times longer.

Proper tire pressure is a big deal.
Maintain it with nitrogen, and you'll see
these three primary benefits:

  • Increased Fuel Efficiency – Correct tire pressure keeps the manufacturer's recommended “contact patch” on the road. This lessens the rolling resistance and maximizes fuel efficiency.
  • Longer Tire Life – When it comes in contact with other materials, oxygen causes oxidation. Oxidation can make rubber brittle and cause it to lose tensile strength. In addition, at high temperatures and pressures, oxygen reacts and damages inner tire liners and belt packages; nitrogen does not.

  • Increased Safety – Under-inflated tires cause 90% of blowouts. Nitrogen provides more reliable pressure for reduced blowout potential.

Other benefits:

  • Improved TPMS Performance – If you have a new car, you likely are plagued by a flashing light telling you your tire pressure is low. For example, one woman's light was going off every four to five weeks. After inflating with nitrogen, her light didn't reappear for 53 weeks!

  • More Predictable Pressure Fluctuation – NASCAR teams use nitrogen so they can more accurately predict tire pressure fluctuation. Regular compressed air can fluctuate considerably when water vapor is present.
  • Longer Rim Life – Rim rust caused by condensation from water vapor and other gases can get caught in valves and create slow leaks in tires. Nitrogen is completely dry, so it eliminates the potential for condensation.
 

Why not eliminate all oxygen and water vapor?
What's right for me – 95% or 98%?

Numerous studies have proven that nitrogen in tires reduces the volume of gases that escape more quickly and cause damaging oxidation. However, research also has shown that nitrogen purity beyond a certain point does not provide additional benefits. In fact, with a nitrogen purity above 93.4%? in passenger tires, oxygen actually begins to migrate back into the tire. You can get all the benefits of nitrogen with a purity level between 93-98%.

  • Bridgestone/Firestone researchers say that 93-95% nitrogen is all you need.

  • According to Ford Motor Co., there is no difference between 96% and 99% nitrogen purity.

Who Else Is Using Nitrogen?

  • NASCAR - NASCAR teams use nitrogen because it allows them to more accurately predict tire pressure fluctuation. Nitrogen fluctuates with temperature change, but it does so less than when water vapor is present.  In addition, higher nitrogen levels eliminate the explosive properties of oxygen (oxygen loses its explosive properties at around 9% or less) NASCAR uses bottled nitrogen for portability. The bottles are delivered to the track by Praxair.

  • Commercial Airlines – The Federal Aviation Administration (FAA) requires nitrogen in all commercial aircraft tires to eliminate the potential for water vapor (inherent in normal compressed air) from freezing at high altitudes. In addition, aircraft manufacturers such as Boeing use nitrogen membranes in their On-Board Inert Gas Generation Systems (OBIGGS) to "top" fuel tanks with nitrogen - an inert gas that does not support combustion.

  • U.S. Government – NASA and the U.S. military use nitrogen for many of the same reasons it used in commercial aircraft.

  • Food Processors and Packagers – Oxygen hastens both the chemical breakdown and microbial spoilage of many foods. Think meat, potato chips, cookies, etc. To help preserve foods longer, processors and packagers often use modified atmosphere packaging (MAP) and controlled atmosphere packaging (CAP) that replaces some or all of the oxygen in the air inside the
    package with nitrogen.

How is nitrogen separated from other gases in air?

Membranes are the heart of any nitrogen system. Just like a tire, the membranes are permeable. When thousands of these permeable tubes are filled with air at high pressures, smaller molecules leak out while the larger nitrogen molecules travel through the tubes into a holding tank to fill your tires or
for other uses.

 

*this article was provided by http://www.getnitrogen.org/why/index.php more information can be found thier site.