Choosing Your Tires

What you are looking for in a tire?

People replace their tires for a variety of reasons. Some people just want a "better looking" tire on their vehicle. For example, they want outlined or raised white letter tires - something that will set their vehicle apart. Other people want to improve the performance of their vehicle, so they look to replace their tires with ones that will deliver better performance. Most of us replace our tires simply because we need to.

"Appearance tire" case, you are not usually overly concerned with prices. You just want something that will look good on your vehicle and deliver a quality ride. Most manufactures make tires with some kind of lettering on the sidewall of their tires because there is a "niche" market out there. When replacing standard size blackwall or whitewall tires on your vehicle, make sure you replace them with acceptable optional replacement sizes. Since many standard size tires do not come with raised or outlined lettering, quite often you will need to move to an optional size tire. For example, a P195/75R14, a popular standard size, can often be replaced with a P205/70R14. You may need to look in your owner's manual or consult a tire professional to see if your vehicle can handle an optional size.

"Performance tire" case when you're replacing the tires, you have one goal in mind: to improve the performance of your vehicle. Most often, that means buying a tire with a shorter sidewall and a wider footprint. That increases the vehicle performance by cutting lag time in the turns and giving better road traction. Moving to a different size tire will mean replacing wheels to further enhance the performance. This is called "Plus 1" or "Plus 2". To move from a 15" to a 16" tire (plus changing wheels from 15" to 16") is Plus1. An example would be replacing a P205/70R15 tire with a P225/60R16. Ultra performance tire buyers may even move to Plus2 by changing to a 17" wheel. The replacement size then would be a P235/45R17.

The largest group of people replacing their tires is those who just need new tires.

Replacing tires because we need new tires on the vehicles. Your tires are worn out and no longer serve a purpose. Advanced or unusual tread wear needs immediate attention. Tires must be replaced when tread is at 1/16 of an inch.

Selecting Tires

 When it is time to replace tires, there are five factors worth considering: Selection, prices, mileage, warranty, and retailer

Selection

There are advantages to choosing from a good selection of tires. Seek a tire professional that not only offers different brands, but several choices within each brand that will also offer a broad price range and quality

Price

Tires are sold in large price ranges. A single price range may come with a certain set of characteristics such as mileage, traction, and performance capabilities. Purchasing an "expensive" tire does not always equate to getting higher mileage. Some of the more costly performance tires are not made to deliver the miles, but rather, hold the road better. They stick like glue - but because of the softer, more pliable tread compounds, they may wear quicker.

Mileage

Mileage is another consideration. Determine how long you will keep your vehicle and how long you want your tires to last. Longer mileage tires usually equate to a little higher price, but depending on how long you keep your vehicle, it may be the last set of tires you need to purchase.

Warranty

Explore the details of warranties and ratings. Make sure your tires come with a manufacturer's warranty. Some tires come with mileage warranties. Most tires come with a manufacturer's warranty against defects in workmanship and materials. Find a tire retailer that will offer a nationwide warranty on its tires. With the huge increase in light truck and sport utility vehicle, many people want to know whether they should put a passenger rated tire or a light truck tire on their vehicle. A light truck rated tire has an "LT" designation in its size. For example, LT235/75R15 means it is for a light truck vehicle. Passenger sizes have a "P" in front of the size or no letter; P235/75R15 or 235/75R15. Both tires are the same size but have different purposes. Usually light truck sizes can carry more weight and have a little stiffer sidewall. Whichever tire you choose, make sure it meets or exceeds the manufacturer's load carrying capacity.

Selecting Retailer

Finally, find a reputable tire retailer that offers a wide range of brand selection, a range of prices and a good solid warranty. Feel free to ask a lot of questions and get the answers you need to make the right buying decision.

How to read tire markings

Passenger Tire markings are typically shown as:

For Example, above Tire size P215/65R15 89H Means

-         The "P" stands for "P-Metric" or "Passenger". This means that it is a North American tire sizing designation. European tires typically don't have the "P" attached to the size. Tires with higher ply ratings will generally start with "LT" which stands for "Light Truck". This indicates the tire is an LT metric and will always have a Load Range indicated. It is important to note this for vehicles that call for LT metric tires. Never substitute a P metric tire for an LT metric tire, even if all the other dimensions are the same.

-         The "215" is the width of a tire, also known as the "section width". This is the width of the tire in millimeters at its widest point from sidewall to sidewall when mounted on the recommended rim width. The actual tire width can vary depending on the rim width it is mounted on.

-         The "65"is known as the Aspect Ratio. It is calculated by dividing the section height by the section width and multiplying by 100. (In this example, the sidewall will be 65% of 215)

-         The "R" stands for Radial, meaning it has a radial construction. Radial tires have ply cords that extend to the beads and are laid at 90 degrees to the centerline of the tread, the carcass being stabilized by a circumferential belt. Other possibilities include "B" for belted construction and "D" for diagonal construction. This means the ply cords extend to the beads and are laid at alternate angles less than 90 degrees to the centerline of the tread.

-         The "15" stands for the diameter of the wheel in inches. This is the exact size that this tire will fit. There are some older rims called "TRX" which are metric measurements like 390. You CAN NOT mix TRX rims with regular tires or vise-versa.

-         The "89" is the load index

-         The "H" is the speed rating.

Speed Ratings

The speed rating of any tire is a measurement of the top safe speed the tire can carry a load under specified conditions. It is also an indication of how the tire will handle at lower speeds. A higher rated tire will give you better traction and improved steering response even at 50mph.

Below is a listing of common speed ratings:

Caution: Never mix tires with different speed ratings on your vehicle.

Load Ratings

The load rating for any tire (load index) indicates the maximum weight that each tire is able to support. Here is a quick rating of common Load Indexes:

Sidewall Markings

Here are some other markings you may find on your tire's sidewall:

• The M+S (also displayed as M&S or M-S) indicates the tire has all season capabilities. You will find this on almost all all season and winter tires. Summer tires will not have this designation. For a tire to get this designation it must have a specified tread-to-void ratio; however it does not mean that the tire has passed any actual tests for it effectiveness in severe conditions.
• DOT stands for Department of Transportation. The 10, 11 or 12 digit code appearing after the DOT designation gives information such as the week and year the tire was produced, as well as the manufacturer, plant, tire line, and size. The first 2 characters designate the tire's manufacturer and plant code. The third, fourth and fifth characters, are the tire size code. The last three or four numbers (4 numbers for years after 2000) are when the tire was manufactured. The first two digits of the date code represent the week and the last 1 or 2 digits represent the year.
• Maximum Inflation Pressure is the highest inflation pressure that the tire can withstand. This is not, however, the recommended inflation pressure. Inflation pressures should never be below the recommended pressure or above the maximum pressure branded on the sidewall.

Sidewall Descriptions

Below is a quick legend to notations describing the appearance of the tire's sidewall.

Uniform Tire Quality Grading (UTQG)

The Uniform Tire Quality Grading rating is a quality rating system developed by the Department of Transportation. It is designed to tell consumers the relative performance of passenger tires (but does not apply to winter tires).

Example:150A B

The "150" indicates the treadwear rating
the "A" indicates traction
the "B" indicates temperature

The Treadwear rating is based on a wear test performed on a 400 mile government test course covering specified sections of public roads in Texas. A group of not more than 4 test vehicles travels the course in a convoy so that all tires experience the same conditions. Tread groove depths of the tires being tested are measured after each 800 miles. The same procedure is followed for a set of "control" or "course monitoring tires" Upon the completion of the 7200 mile test, the rating results of both tires are compared, and the tires being tested are assigned a treadwear rating according to government standards. This number can be used to compare between tires. In the above example, this tire rated 150 should last 1/2 as long as a tire rated 300. The relative performance of tires depends upon the actual conditions of their use and may be significantly different from the norm due to differences in road characteristics and climate.

The Traction ratings are AA, A, B, and C, from highest to lowest. This measurement indicates a tires ability to stop in a straight line on wet pavement. The rating is based on a 40mph test where the brakes are "locked up" on wet asphalt and wet concrete surfaces. It's important to remember that this rating does not indicate the tires ability to resists hydroplaning, and do not apply to cornering traction.

Temperature ratings are determined by running tires on an indoor road wheel test under specified conditions. Successive 30-minute runs are made in 5mph increments starting at 75mph and continuing until the tire fails. Tires with an A rating must withstand at least 114mph, B at least 99mph, and C at least 85mph. These measurements indicate the tire's ability to sustain high temperatures, which often cause tires to wear away quickly or in extreme conditions lead to sudden tire failure.

Maintenance of Your new tires

Five Most Important Tire Saving Tips

         Check tire pressures regularly - with a good tire gauge, before you drive, when tires are cool. Don't guess - read your owner's manual or the vehicle's door jamb for proper pressure. Don't under- or over-inflate them.

         The first tire rotation is the most important. When regularly rotated, your tires will last longer and produce even tread wear. Follow your owner's manual guidelines, or the rule to rotate tires at every 5,000 - 6,000 miles.

         When you replace your tires, have them computer balanced. Have the balance checked when you rotate them. Balanced tires create a more comfortable ride and will last longer.

         Not aligning your vehicle may cause poor handling and worn tires. A jolt can wreck the alignment. Have a tire dealer check it periodically.

         Look for uneven tire wear, high and low areas, and damage. An easy wear test: place a penny headfirst into a tread groove. If tread hides part of Lincoln's head, you have enough tread. An entire head means you have low tread and need new tires.

Mixing Tires

Generally tires should not be mixed on any vehicle. To receive maximum safety and performance it is preferable to keep every tire on a vehicle identical in size, brand, model, rating etc. One of the only exceptions is if the front and rear wheels are different like on all Porsche's and other high performance vehicles.

Air Pressure

The most common way of damaging tires is improper inflation. As tires lose pressure over time it causes them to experience irregular treadwear, poor vehicle handling and traction, and decreased gas mileage. Under inflated tires can build up excessive heat and blow out without warning. Pressure should be checked at least once a month using a good quality tire pressure gauge. Pressure should be checked when the tires are cold (tires have not been driven for 2 hours). You can find out what the proper inflation numbers on your tires are by checking the owner's manual of your vehicle. Even if the tires have been changed since the vehicle was new, the car manufacturers recommended pressures still apply.  Also remember to check your spare tire for loss of air.

Tread Wear Indicator

As your tires wear down, their ability to grip the road decreases. Each tire has what are known as wear bars. These appear at various points around the tire as bars running through the tread design from one side of the tire to the other. When your tires are legally worn out (2/32") the tread will be at the same level as the tread wear indicators and they will be easily visible. Usually before the tire gets to this point, they will begin to feel unsafe. If that is the case, do not wait for them to get to the wear bars. Just because the tread depth is not as low as the tread wear bar, does not mean it is safe.

Tire Rotation

Because each tire on your car typically supports a different amount of weight, and your driving patterns will typically wear out one tire faster than the others, it's important to rotate your tires every 5000 to 8000 miles. Rotation patterns differ depending on what kind of vehicle you drive. The best place to check is in your vehicle's owners manual. If you cannot find what you are looking for, below are some diagrams showing you the most common patterns.

Of course, if your vehicle has different sizes of tires from front to back, or if your tires are directional, these may not work. Consult a professional if you are still not sure.

Alignment

Vehicle alignment is one of the most important factors in tire care. For most vehicles, poor alignment results in excessive and/or uneven tire wear. Improper alignment can reduce a tire's life by more than 70%. Improper alignment on either the front or rear wheels can result in unusual tread wear, damage to your suspension, and unusual handling for the car. Wheel alignments should be performed every time you install a new set of tires, and any time you experience an impact such as a large pothole, curb, or other obstacle. For maintenance purposes, alignment should be checked every year.

There are several alignment types, including both two and four wheel alignment. Four-wheel alignment is always recommended, but some vehicles are not able to have the rear alignment adjusted. Consult with an alignment specialist you trust to find out what's best for your car.

Warning signs that you might need an alignment are your car pulling to one side or another and irregular tire wear.

Puncture Repairs

A puncture to any area of a tire's tread will affect performance and safety, and therefore must be immediately attended to through either replacement of the tire (spare or new tire) or a patch. Any patch that is applied to a tire must be applied to both the outer part of the tire (tread) and the inner part of the tire. The reason for this is that the rubber on each side is very different (inside is made of halo butyl rubber meant for holding air, while the outside is a harder durable rubber primarily designed for traction). A good tire repair can only be made if the tire is removed from the rim (wheel) and inspected carefully for any hidden damage. Only straight through holes, 3/16" or smaller diameter may be repaired, when no secondary damage has occurred.

Noise and Vibration Problems

Below are the most common (but not the only) causes of noise and vibration problems:

- Tire / wheel assembly is out of balance

- No hub rings on aftermarket wheels

- Incorrect mounting hardware for aftermarket wheels

- Tire is poorly seated on the rim

- Irregular tire wear

- Out of round rim

- Out of round tire

Do not ignore apparent impacts, pulling, or vibration. This could be an indicator of tire damage as much as mechanical problems that should be inspected by a professional. If there is a problem with your tires and the way they have been installed they will most likely begin to shake and vibrate your vehicle at between 50 and 65 mph.

Mounting and Balancing

When mounting wheels & tires on to the vehicle, ensure the following checks are made:

- Wheels are not damaged in any way

- There is no dirt or oily build up between the hub and the wheel

- Lugs are properly torqued

- Both tire beads are securely mounted

- Any retaining clips on the brake drums are removed

Tires are manufactured to close tolerances, however as they wear their mass can become unevenly distributed, negatively affecting the original balance. The most common signs of unbalanced tires are vibration problems. These can affect the speed, handling, and mileage of your vehicle. Balancing is done by a computer that spins the wheel / tire assembly, senses heavy spots, and gives a location for the technician to apply weight to counter the heavy spots. The best type of balance is a dynamic balance, and this should be performed whenever possible. (Some rim designs will not allow this type of balance and you would have to settle for a static balance)

Frequently Asked Questions

Q. What does the TREADWEAR grade tell about a tire?

A. The higher the number, the greater tread life you should expect. A tire with a grade of 200 should give you twice as much mileage as one rated at 100, provided that you keep the tires inflated properly, the wheels aligned and tires balanced and drive then under normal conditions.
Failure to care for your tires will greatly reduce the tread life and can also create a safety hazard. How you drive, and under what road conditions, also affect treadwear.

Q. So the TREADWEAR grade will not tell me for certain how many miles of tread life I can expect?

A. Correct. It is not a measure of tread life. It indicates on that, under the same general conditions, one tire can be expected to produce more mileage than another, not what the mileage will be. Again, actual tread life is strongly influenced by where you live and how you drive. In some parts of the country, tires wear out faster. For example, the local rock used for road construction is rougher in some geographical area than in others. The same tire might give 20,000 miles in one part of the country and 30,000 in another, but a tire with a higher grade should produce better tread life than a lower graded tire in either locality.

Q. Will all drivers get the same mileage on the same grade of tire?

A. No. Mileage is determined primarily by driving habits. Drivers who start off slowly can expect the best tread life. Those who consistently make "jack rabbit" starts and stops and fast tire screeching turns will get the least.
Studies have shown that treadwear for the same tire can be as low as 14,000 for some drivers, but as high as 30,000 miles for other drivers in the same geographical area. Proper maintenance is also important. Under- or over-inflation, unbalanced wheels and wheel misalignment results in uneven treadwear that causes the tire to wear out prematurely.

Q. What does the TRACTION grade tell me about the tire?

A. In a straight line stop, the "AA" graded tire should allow you the stop your car on wet roads in a shorter distance than tires graded "A", "B" or "C". When driving on wet roads, good traction is important to your safety. Tires graded "C" offer the least traction on wet roads.

Q. Is the ability to stop the car affected by anything besides the tire grade?

A. Yes. When the tread is badly worn, all tires lose much of their stopping ability, especially on wet roads.
For safety reasons, it is important to replace tires when the built-in treadwear indicators begin to show (you will see lines across the tread when the groves measure only 1/16 of an inch deep (about the thickness of a nickel).
Regardless of the traction grade a bald tire is dangerous. Keep in mind that properly maintained brakes are also extremely important to stopping performance.

Q. Is TRACTION improved if you let some of the air out of the tires, below the recommended pressures?

A. No. In fact, this is a dangerous practice. Under inflation does not improve traction. It causes the tire to run hot, which can damage it and increase the risk of a blowout. It will also wear out the tread faster and reduce your car's fuel economy. Proper tire pressure information can be found in the vehicle owner's manual and on the tire information placard on the vehicle.

Q. What does the TEMPERATURE RESISTANCE grade tell me about a tire?

A. Sustained high temperatures can cause the tire material to degenerate and excessive temperatures can lead to blowouts and tread separations. The "A" rating signifies the coolest running tire.
If the vehicle and tires are maintained and operated properly, they should perform safely and reliably when run at the speed limit, even in very hot weather. "C" tires run hotter than tires graded "A" or "B", but a "C" graded tire is not "UNSAFE".
Keep in mind that under-inflation or overloading will overheat and damage any tire and greatly increase the likelihood of a blowout.

Q. What significance does the TEMPERATURE RESISTANCE grade have for me as a driver?

A. If you often drive at highway speeds for periods of an hour or more, there is less chance a cooler running "A" graded tire will overheat than a "B" or "C" graded tire. All tires should perform safely and reliably when driven at the speed limit, but higher graded tires will give you a greater margin of safety. Your individual driving habits and the amount of time you spend driving in hot climates or at highway speeds should determine how much emphasis you put on the temperature resistance grade.

Q. Is the temperature of my tires affected by anything other than the assigned grade?

A. Yes. All tires will run higher temperatures when they are under inflated or over loaded. It is very important to check the pressure in all of your tires before starting out on a trip where you will be driving at highway speeds for more than an hour. Always inflate the tires to the recommended pressures before starting on the trip. This precaution will help any tire run cooler.

Q. How much air should I put in my tires?

A. Proper inflation is the single most important part of tire care. The inflation pressure on the side of the tire is the MAXIMUM operating pressure. It is not necessarily the right inflation for your vehicle. Always use the inflation recommended by the vehicle manufacturer. You can find it in your owner's manual, posted on the edge of the driver's door, on a doorpost or on the inside of the glove box door. Always check inflation when tires are COLD: when the vehicle has been driven less than a mile or one hour or more after driving. Use a good quality tire gauge. Note: It is natural for radial tires to have a slight bulge in the sidewall at their proper inflation pressure. Check or adjust inflation every few weeks, before any long trip or if traveling with a heavy load.

Q. What is alignment?

A. A vehicle is said to be properly aligned when all suspension and steering components are sound and when the tire and wheel assemblies are running straight and true. Proper alignment is necessary for even tread wear and precise steering. Uneven front-or rear-tire wear, or changes in your vehicle's handling or steering response (i.e. pulling to one side) can indicate misalignment. Many vehicles today are equipped with rear suspensions that can be adjusted for alignment. Your vehicle may need a "front-end" alignment or a "four-wheel" alignment, depending on the symptoms you are experiencing. The moderate costs of having your vehicle aligned can more than pay for itself in tire mileage, performance and comfort.

Q. What should I do if I notice a vibration?

A. Vibration is an indication that your car has a problem that needs attention. The tires, steering system, and suspension system should be checked to help determine the possible cause and correction of the vibration. If left unattended, the vibration could cause excessive tire and suspension wear. It could even be dangerous.

Q. Why do my tires need to be balanced?

A. Properly balanced tires are important for driving comfort and long tire life. Unbalanced tires can cause vibration, resulting in driver fatigue, premature tire wear and unnecessary wear to your vehicle's suspension. Tires should be balanced when they are mounted on wheels for the first time or when they are remounted after repair. Tires should be rebalanced at the first sign of vibration or "shimmy." Vibration may also be due to misalignment or mechanical problems.

Q. Do my new tires require any special treatment?

A. Your new tires will probably feel different from the tires that were replaced. Drive carefully as you become familiar with their performance and handling. Take special care when braking, accelerating, cornering, or when driving in the rain, because these are the times when the differences will be most noticeable.

Q. How long should my original equipment tires last?

A.  Due to the variety of styles, construction features, treat compounds, vehicle applications, geographical conditions and driving habits, it is difficult to provide specific mileage expectancy. However, any tire wear concern should always be presented to tire professional for further evaluation.

Q. Is it easy to mount a tire on a wheel? Can I do it myself?

A. Never try to mount your own tires. Tire mounting is a job for the people who have the proper equipment and experience. If you try to do it yourself, you run the risk of serious injury to yourself as well as possible damage to the tire and rim.

Q. Must I replace my present tires with the same size tires?

A. Never choose a smaller size than those that came with the car. Tires should always be replaced with the same size designation -- or approved options -- as recommended by the vehicle manufacturer.

Q. Should I "mix" tire types on my car?

A. Tires of different size designations, constructions, and stages of wear may affect vehicle handling and stability. For best all-around performance, it is recommended that all tires be of the same size, construction (radial, non-radial), load capacity, and speed rating.

Q. When buying just two new tires, should they be put on the front or rear?

 A. When you select a pair of replacement tires in the same size and construction as those on the car, you must put them on the rear axle. A single new tire must be paired on the rear axle with the tire having the most tread depth of the other three.

Q. How can I check my tires for wear problems?

A. Tires often give their owners signs of problems in plenty of time to have them corrected. Learn to "read" these early warning signs and you can prevent many wear problems that shorten tire life by thousands of miles. Consult your tire sales associate for further information.

Q. How do I know when I need new tires?

A. Many tires have tread wear indicator bars molded into the tread. When the tread is worn down to where you can see a solid bar of rubber across the width of the tread, it is time to replace the tire. Here is another simple test you can perform to measure tread depth on your tires. Place a penny into a tread groove with Lincoln's head upside down and facing you. If you can see the top of Lincoln's head, it is time to put a new tire.

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