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Despite advances in longer-lasting tires, actual tread life will vary by car type, tire type (such as all season or high performance), driving aggressiveness, and even road and weather conditions. Car owners still need to replace their tires a few times or more throughout the life of a typical vehicle. As the adage goes, nothing lasts forever.
Proper maintenance and responsible driving can maximize the mileage in a set of tires. Monthly tread inspections can inform when the tires warrant replacement, well in advance of the federally mandated tread-wear indicators. In most states, tires are legally worn out when their tread depth reaches 1/16 inch (or 2/32 inch as found on standardized tread-depth gauges). The easiest way to measure this, if you don't have a gauge, is to hold a penny upside down in the tread. If the top of Lincoln's head is visible, you need new tires. But using a penny standard doesn't work for all weather conditions. We have found in our tests that a tire with just 1/8-inch tread was notably worse in hydroplaning resistance and snow traction. By the time only 1/16 inch remains, wet-pavement cornering and braking drop off too. Based on our experience, when your tires have less than 1/8 inch of tread left, it's a good time to start shopping for replacement tires.
As a better indicator of tread wear, place a quarter upside down in a tire groove. The distance from the coin's rim to George Washington's hairline is about 1/8 inch. If you see all of his head in any one groove where a tread-wear indicator appears, consider shopping for new tires.
Once a need for new tires is determined, it is necessary to identify the best tires for your vehicle and driving demands.
Put safety first
Look for tires that do well in our tests for braking, handling, and resistance to hydroplaning. Winter traction should also be considered, if applicable. Let tread wear, ride comfort, noise, and rolling resistance be tiebreakers. Our comparative tread-life tests demonstrate that a manufacturer's warranty doesn't always reflect how a tire will wear.
The tread-wear warranties manufacturers provide for their tires are pro-rated; the more miles on the tire, the less credit you get on a replacement. And most tire warranties only cover damage resulting from regular use and don't cover damage resulting from potholes or other road hazards.
Tire prices can vary widely by region, and retailer. Check independent tire dealers, online or mail-order stores, tire chains, car dealerships, department stores, and warehouse clubs. Be sure to ask whether the price includes mounting, balancing, and new valves, which can increase the total cost.
Look at the sidewall of a tire for a designation beginning with DOT (for Department of Transportation). The last four digits of the designation indicate the week and year of manufacture. For example, 3313 means the tire was made during the 33rd week of 2013. Don't purchase tires that are more than a few years old.
There is a wide range of tires types and size available from popular brands such as Bridgestone, Dunlop, Goodyear, Michelin, and Pirelli. It pays to know what is currently on your vehicle and to learn about your options. There are three basic types of tires--car, truck, and winter--and each has a few choices in each category.
The choice of a car tire depends on how you drive, the type of tire included with your car, and the performance you want.
come in sizes to fit everything from small cars to light-duty SUVs and pickups. They are a popular choice for many older vehicles and are for drivers who want year-round traction, long tread wear, and a comfortable ride. But they typically lack the precise handling and grip of performance tires.
Speed Ratings: None, S (112 mph), T (118 mph)
Tread-wear warranty: None or 40,000 to 100,000 miles
Typical wheel size: 14 to 17 inches
have a higher speed rating than standard all-season tires. They generally provide better handling and braking, and usually have a lower profile (shorter sidewall height) and a wider footprint. They are a popular choice for many newer cars.
Speed Ratings: H (130 mph), V (149 mph)
Tread-wear warranty: None or 40,000 to 60,000 miles
Typical wheel size: 15 to 17 inches
are commonly fitted to upscale sedans or sporty vehicles. These tires are designed to provide good handling and responsive steering in wet and dry conditions, but the tread wear and ride comfort are common compromises. Summer versions are not intended for cold weather and won't grip in snowy or icy conditions. All-season versions tend to provide a compromise of dry and wet grip relative to summer tires for all weather conditions.
Speed Ratings: ZR (more than 149 mph), W (168 mph), Y (186 mph)
Tread-wear warranty: None or 30,000 to 40,000 miles
Typical wheel size: 17 to 22 inches
Because of their size, dynamics and how they are used, trucks and SUVs often require special tires. Some automakers advise sticking with the tire type that the vehicle originally came with. Consult the owner's manual to see if a specific type is recommended. You can often improve road handling by switching from an all-terrain tire to an all-season.
are well rounded and are good for road driving. They are designed to perform reasonably well in most conditions.
are suited to paved roads and light-duty off-road use. They provide added traction on unpaved and snowy roads.
Speed ratings: S (112 mph) for many.
Tread-wear warranty: None or 40,000 to 60,000 miles.
Typical wheel size: 15 to 20 inches.
If you drive often in wintry or icy conditions, then winter tires might make sense for you. Winter tires typically have faster tread wear than all-season tires because the tread is specifically designed to bite into snow and ice, and the rubber is formulated to stay pliable at freezing temperatures. Winter tires have a mountain/snowflake symbol on the sidewall. It indicates that they passed an industry test for severe snow use. All the winter tires we tested carry that symbol. Don't be misled by the M&S (mud and snow) designation found on the sidewalls of a tire. That doesn't mean it's a winter tire; it means only that the tire has a relatively open tread pattern.
Winter tires have treads with more biting edges for better grip on snow and ice, while their softer compound remains flexible even in extremely low temperatures. But on cleared roads, they might not grip as well as all-season tires and they often wear more quickly.
provide higher levels of snow and ice grip, but keep some of the handling and cornering capabilities of performance tires.
Speed Ratings: Q (99 mph) and higher
Tread-wear warranty: None
Typical wheel size: 14 to 18 inches
The dimensions necessary to describe the tire fitment, found on the sidewall. In addition, you'll find the recommended tire size, as well as the speed and load ratings for your vehicle on a placard in the doorjamb, the glove compartment, or on the fuel-filler door. To understand how size, works, consider the common: P235/70R16. In this example, P denotes passenger-car tire, even though the tire may be designed for a light truck (an LT, or light truck, prefix is for heavy-duty light-truck tires). The number 235 is the cross-section width in millimeters, while 70 is the ratio of sidewall height to cross-section width (70 percent). R means radial-ply construction and 16 is the wheel diameter, in inches. Check out our report on how to read a tire for more details.
Found on the tire sidewall, this letter denotes the maximum sustainable speed and is found directly after the load index. For S-speed-rated tires, it's 112 mph; for T, 118 mph. Speed ratings for other tires include Q, 99 mph; H, 130 mph; V, 149 mph; and Z, 150 mph plus. While such speeds may seem wildly impractical, tires with higher speed ratings tend to provide better handling at legal speed limits. Choose tires that have a speed rating at least as high as the one specified on your vehicle's placard. The one exception is winter tires. Look for a winter with that is close or the same speed rating as specified on the placard.
Found on the tire sidewall, this number is based on the weight the tire can safely carry. You'll find it after the tire size; the 94 load index for example correlates to 1477 pounds. Choose tires with a load index at least as high as the one that's listed on your vehicle's placard.
Every tire has a Department of Transportation (DOT) number following the letters on the sidewall. The last four digits determine the week and year the tire was made; for example, the digits 2204 would signify that the tire was made during the 22nd week of 2004. Don't buy tires more than a few years old.
This is a tire's maximum air pressure, given in pounds per square inch. But that doesn't mean you should inflate your tires to that pressure, since automakers typically recommend an inflation pressure well below the tire's maximum air pressure. Follow the advice on the vehicle's placard, often located in the driver's doorjamb, or owner's manual.
The vertical side of the tire, surrounding the wheel, is called the sidewall. Here you'll find important information, such as the tire size and load and speed rating, necessary to choosing a replacement.
These scores denote a tire's wet-stopping ability and temperature resistance. For traction, AA is best, C is worst. For temperature resistance, scores range from A (best) to C.
A government required grade that indicates how well a tire will wear as compared to a standard reference tire graded 100. In theory, a tire graded 500 should last five times as long as one graded 100. But the tire makers assign these wear ratings.
Consumer Reports provides in-depth tire test ratings of more than 16 major brands of replacement tires sold nationally. Listed below are just some of the major tire companies and the brands they manufacture.
Bridgestone, Goodyear, and Michelin are the top brands of tires sold in the world. Continental, Pirelli, Sumitomo, Yokohama, Hankook, Cooper, and Kumho finish out the top 10. Beyond that, Toyo, Maxxis, Nokian, and many others also sell tires in North America. Use these profiles to compare tires by brand.
Based in Tokyo, Bridgestone is one of the three largest tire manufacturers in the world. Bridgestone Americas Tire Operations has its headquarters in Nashville, Tenn. The corporation manufactures and markets Bridgestone, Firestone, Dayton, and Fuzion tires, among other associate brands. It supplies tires for most applications in the United States. Bridgestone and Firestone replacement tires often score well in our tests.
Continental is in a distant fourth place in North American and global sales, behind Goodyear, Bridgestone, and Michelin. Still, it offers a full complement of original and replacement tires. The Germany-based Continental Corporation is a top automotive supplier of brake systems and various vehicle components, in addition to tires. The U.S. tire operations have headquarters in Lancaster County, S.C. The company sells the Continental and General tire brands. In the past, General has shined for light-truck tires in our testing.
One of the few independent tire manufacturers in the U.S. with origins going back to the early 20th Century, Cooper is among the world's top-10 tire makers. Based in Findlay, Ohio, Cooper Tires offers a full array of tires, including the Avon, Mastercraft, and Starfire brands. Cooper tires are most often sold by independent dealers, though they can be found online. In the past, Cooper has been a standout among light-truck tires.
Goodyear claims to be the best-selling tire-maker in North America and is one of the leading tire manufacturers in the world. In 2008, it ranked third behind Michelin and Bridgestone for global tire sales. Based in Akron, Ohio, Goodyear is a major supplier of original and replacement tires and sells tires for most applications. Founded in 1898, Goodyear owns the Dunlop and Kelly-Springfield brands of tires sold in the United States. Goodyear and Dunlop have often been top picks in our Ratings.
A Korean corporation, Hankook has its North American headquarters in Wayne, N.J., and a technical center in Akron, Ohio. Hankook is original equipment on several foreign and domestic auto nameplates. It also offers a complete line of replacement tires to fit most domestic cars and light trucks. Generally, Hankook tires we have tested offer good value for their well-rounded, all-weather performance.
This Korean tire maker started in 1960, and today it is one of the top 10 tire manufacturers in the world. Kumho offers a full array of car and light truck tires. Their tires are noted for excellent value and good all-weather performance, based on our tests.
A French company, Michelin has its North America headquarters in Greenville, S.C. As a global tire maker, it offers tires for nearly all applications. In North America, it owns the BFGoodrich and Uniroyal brands. Founded in 1891, Michelin first introduced the radial tire, and the company continues to be a pioneer in tire technologies. Michelin tires generally perform impressively in our all-weather tests and offer many models with low rolling resistance and long tread life.
Pirelli is based in Milan, Italy, and it has a U.S. manufacturing plant in Rome, Ga. Pirelli caters to the high-end market with tires commonly found on luxury and sports cars. It has a stronger presence in Europe than in the United States, and yet Pirelli offers a full line of replacement tire models to fit most cars and light trucks sold in North America. It is an original equipment supplier to the domestic car manufacturers on selected car models. The Pirelli Group business sectors also include real estate, broad-band solutions, and environmental technologies. In our testing, Pirelli tires often impress us with their dry and wet grip and handling.
Yokohama is a Japanese company with a global presence. Its North America headquarters are in southern California. Targeting performance enthusiasts, Yokohama tires place emphasis on handling and dry and wet grip. Its tires reflect this focus, our testing shows. Generally, we find that Yokohama tires are a good choice for consumers who live where winter driving is not a factor.
Longer-lasting tires make safety checks more critical than ever. While yesterday's tires typically wore out in 30,000 miles or less, many of today's are warranted for two to three times that mileage. That means they may still have lots of tread even though heat, the environment, and potholes may have weakened them.
Underinflated tires can also get hot and weaken, increasing the chance of a blowout. A 10° F drop in outside temperature lowers pressure by about 1 pound per square inch. What's more, all tires tend to leak over time. Pressure loss averaged 6 psi for 36 all-season models we checked after one year.
To help keep your tires safe:
It has long been the standard that tires are worn out when their tread depth reaches 1/16 inch (or 2/32 inch as found on standardized tread-depth gauges). The easiest way to measure this, if you didn't have a gauge, was to hold a penny upside down in the tread. If the top of Lincoln's head was visible, you needed new tires. See test results of foul weather comprises with worn-out tires.
But CR's tests show that using a penny is too stingy and that most consumers should consider replacing their tires when the tread reaches 1/8 inch.
To get a handle on how much tread depth makes a difference, we tested two models of V-rated performance all-season tires, a kind widely available on new cars. We subjected sets with full tread, 1/8 inch, and 1/16 inch to our standard battery of tests. Tires were shaved to simulate a worn condition, although the effects of tires' aging could not be taken into account.
Though performance on dry pavement actually improved a bit, the 1/8-inch tread was notably worse in hydroplaning resistance and in snow. By the time only 1/16 inch remained, wet-pavement cornering and braking had also dropped. This suggests that when your tires have less than 1/8 inch of tread left, it's a good time to start shopping for replacement tires.
A vehicle's tires play a crucial role in a car's safety. As the only parts of the car that physically touch the ground, they are one of the key factors affecting a vehicle's handling and braking, and overall highway safety. What steps can you take to ensure that your tires stay in optimal condition? Performing regular checks is quick and easy, and a worthwhile investment of time in your and your family's safety.
Visually inspect your tires on a regular basis. If you note any of the following early warning signs, have a professional inspection performed, check and correct items that may be causing the condition, or replace your tires.
Surveys have shown that as many as half the cars on the road may be riding on one or more underinflated tires. Part of the problem is that tires lose air through the rubber and at interfaces with the wheel and valve, sometimes so slowly that many people don't realize it has happened. Seasonal temperature changes may also cause the tire pressure to drop.
Because the sidewall flexes more at lower tire pressures, underinflation compromises the driving control that a tire is designed to provide. Even a small pressure loss--such as 4 psi--can affect a car's handling, making it harder to control. It can also make the ride softer and the car wallow. In addition, underinflated tires lower a vehicle's fuel economy, which can cost you more money at the pump.
A sidewall that flexes too much can also cause heat to build up excessively, which can shorten a tire's life and possibly lead to a tread separation or blowout.
For additional information on the effects of underinflated tires, see our report on early warning signs of tire failure.
Filling tires with nitrogen rather than air is becoming a common practice in the replacement tire market. This service offers tire dealers another avenue for making money while also promoting safety. The claimed safety benefits often include the potential for reducing pressure loss compared to an air-filled tire. Maintaining proper inflation can help prevent tire overheating; promote optimum tread life and fuel efficiency; and reduce rubber aging and wheel corrosion.
Consumer Reports wanted to find out if nitrogen is worth the price, so we purchased a Nitrogen Inflation System and checked out how well the inflation held up over a one year period. We evaluated pairs of 31 tire models of H- and V-speed rated, all-season tires. We filled one tire per model with air and the other with nitrogen. The test was quite simple: fill and set the inflation pressure at room temperature to 30 psi (pounds per square inch); set the tire outdoors for one year; and then recheck the inflation pressure at room temperature after a one year period.
The tires were filled and deflated three times with nitrogen to purge the air out of the tire cavity. We also used an oxygen analyzer to be sure we had 95-percent nitrogen purity in the tire--the claimed purity limit of our nitrogen system, which generates nitrogen gas from ambient air.
We conducted a year-long test of the effects of nitrogen in tires and the results show nitrogen does reduce pressure loss over time, but the reduction is only a 1.3 psi difference from air-filled tires. The average loss of air-filled tires was just 3.5 psi from the initial 30 pressure setting. Nitrogen-filled tires lost an average of 2.2 psi from the initial 30 psi setting. More important, all tires lost pressure regardless of the inflation medium, so consumers should check their tires' air pressure routinely. If you decide to have your tires filled with nitrogen, be sure to have them refilled with nitrogen routinely. Like air, nitrogen filled tire pressure will drop as seasonal temperatures fall. No evaluation was done to assess the aging claim.
Overall, consumers can use nitrogen and might enjoy the slight improvement in air retention provided, but it's not a substitute for regular inflation checks. For more information, read our nitrogen and tires Q&A.
Tires that can be driven on for 50 miles or more with no air in them enable drivers to get to a mechanic without having to change the tire after a puncture. Run-flat tires are more than just a convenience; they can add a measure of security by eliminating the need to change a tire in bad weather or in dangerous roadside areas.
While run-flats--which are increasingly common on new vehicles--provide substantial safety benefits, they have some disadvantages, which can be glossed over at the car dealership. Some owners of run-flat tires have complained of premature or uneven wear in certain applications, a stiff ride, high replacement costs, and limited replacement choices. Some owners also say they want the added security of a spare tire, and cars with run-flat systems don't usually carry them. Nor do many cars with conventional tires.
Run-flat tires are self-supporting tires, found on vehicles like the Chevrolet Corvette, Toyota Sienna, and many BMWs have very stiff sidewalls to maintain their ability to carry the vehicle load after air loss. But the added stiffness can lead to a harsh ride.
Some vehicle owners have complained that they were unaware their cars had run-flats when they bought them and only found out when they had to replace the tires. Some all-wheel-drive or pre-2011 Sienna owners gripe of needing a new set after just 15,000 miles. Conventional all-season tires typically last 40,000 miles or longer, and most cost less.
Run-flats are typically found on higher-end sports cars and sedans and models with limited space for a spare. Owners of high-performance cars might not object to the stiffer-riding sidewalls of run-flats, since most of those cars ride on stiff tires to begin with.
Despite the disadvantages and inconveniences of run-flat tires for many, Consumer Reports believes that the safety benefits can outweigh the downsides. And the technology behind them is improving while prices are coming down.
Consumer Reports also recommends that you know what kind of tires a car comes with before you consider buying it.
Discuss tires in our Tire Talkforum.