Selecting the Right Tires

Selecting the right tires for your vehicle is an important decision. Your safety, as well as driving enjoyment over the next years and thousands of miles will be determined by this decision. The information provided here and the advice/recommendations from the experts at the Tire Rack will ensure you select tires that match your vehicle...and the way you drive it!

How Many Tires Do I Need?

Since tires affect the personality and performance of your vehicle, all four tires should be as identical as possible or handling problems may arise. If your tires don't match, it is possible that one end of your vehicle won't respond as quickly or completely as the other, making it more difficult to control.

Consider the Following:

Just One Tire?

If your tires have a lot of remaining tread depth, but you need to replace just one that has been damaged by an accident, road hazard or a vandal, you should replace it with a tire that exactly matches the others. Select a replacement tire of the same brand, line, size and speed rating. While there may be a less expensive tire available, it wouldn't be a bargain this time because it would be different than the other three tires on your vehicle.

A Pair of Tires?

If two of your tires have a lot of remaining tread depth, but you need to replace the other two because they were damaged or have worn out, you should replace them with a pair of tires that come as close as possible to matching your existing tires. While identical new tires are desirable, others of the same size and type can also provide good results. Only consider selecting new tires that are from the same tire category as your existing tires. New tires should be installed on the rear axle.

While your vehicle is being serviced ask your mechanic why one pair of tires have worn faster than the others. Was it caused by a lack of tire rotation, out-of-spec wheel alignment or loose mechanical parts? Once the problem has been found, it can be corrected before it damages your new tires. Keep in mind that your ultimate goal is that all of your tires always wear out at the same time so they can be replaced as a set.

A Set of Tires?

If all of your tires are wearing out together, you have the greatest flexibility in tire selection. If you were happy with the original tires, simply replace them. If you want longer treadwear, a smoother ride or more handling, there are probably tires that will help you accomplish that. Review the tire category types until you find a category description that describes a tire that fits your needs.

Once you know how many tires you will be replacing, determine size and type by answering the questions below:

What Is the Right Size for My Vehicle?

Buying the correct tire size can get complicated, especially if you decide to upgrade from your vehicle's Original Equipment size. The expert sales team at the Tire Rack is always ready to offer performance and fitment advice. Call 888-541-1777.

A tire's first requirement is that it must be able to carry the weight of your vehicle. No matter how good a tire you select, if its capabilities are "overworked" just carrying the load, it will have little reserve capacity to help your vehicle respond to a quick emergency. So when you are in the selection process, make certain that your new tire's size is designed to carry the weight of your vehicle! Don't undersize.

The other size consideration is overall tire diameter. Since many of the functions of today's vehicles are highly computerized, maintaining accurate speed data going into the computer assures accurate instructions coming out. And an important part of the speed equation is your tire's overall tire diameter.

For cars and vans, staying within a 3% diameter change is desirable. Pick-ups and sport utility vehicles (SUVs) are usually engineered to handle up to a 15% oversize tire. Most tire dimensions can be calculated. For more information review the Tire Tech article, "Calculating Tire Dimensions." While at first a 3% diameter increase or reduction in tire diameter may sound very limiting, in most cases it allows approximately a 3/4" diameter change.

Additionally to help with the selection of substitute sizes, a system called "Plus Sizing" was developed. We use Plus Sizing to take into account the diameters of the available tires and the wheels, and then helps select the appropriate tire width that ensures adequate load capacity. Maintaining the tire's overall diameter helps maintain accurate speed data going into the computer.

Do I Need Summer Tires, Winter Tires, All-Season Tires?

Do you drive your car only in sunshine, or also through rain and snow? Do you drive your light truck on the road, off the road, or are you the one responsible for clearing the land to build the roads? To successfully meet each of these driving conditions requires a different type of tire.

Ask yourself these questions to determine which performance category you should choose from:

What Is the Worst Driving Condition I Will Encounter?

If you use more than one set of tires and wheels (for example, summer tires in summer and snow tires in winter), you can select tires that exactly meet your diverse needs. If you use one set of tires for every season, you may get good performance under many conditions, but you will compromise your vehicle's performance when the conditions are at their worst.

So the important thing to do is to select your tires so that they match the worst driving condition you expect to encounter. When you're stuck in the snow or in the mud because your tires don't have the appropriate capabilities, you'll curse their limited performance in your worst driving condition...and you'll quickly forget how smooth and quiet they were at other times!

What Are the Typical Driving Conditions I Will Encounter?

If you only drive around your neighborhood and a "long trip" is one that's just down to the corner convenience mart, almost any tire will do. But if you drive your vehicle on congested city streets and expressways during rush hour you will be better served by more responsive tires. If you drive extensively on the interstates you will want quiet, smooth riding, long wearing tires. Or if you like to drive quickly on twisting roads or through the mountains you will want good handling tires. And if you drive on the track or in autocross events, you will want the best competition tires available.

Balancing the Requirements of Your Driving Conditions

If your worst driving conditions and your typical conditions are similar, one set of tires will be all you need. If you live at the edge of the snowbelt and infrequently get snow you may want to select an all-season tire. If your SUV is used as the family's station wagon and driven on the road all of the time, overly aggressive light truck tires aren't for you (unless you really like the "look").

If your worst driving condition occurs frequently (you drive through snow all winter) and is dissimilar to your typical driving condition (you commute to work on the expressway during the week and spend your weekends at the beach), you may want to consider selecting two sets of tires for your vehicle. Each set will be designed to master the specific conditions without compromising your driving satisfaction at the extremes. While purchasing two sets of tires may appear expensive, the set you're not using won't wear while you are using the other set, and combined they'll provide longer total wear than either set could individually!

How Do I Compare Price Vs. Value?

Why is it that the price of fuel for our vehicle seems relatively inexpensive while the cost of tires seems high? (Of course you already know that the Tire Rack tries to keep your tire costs as low as possible!) If we keep track of our total costs we will find that typical total fuel costs for just 10 to 20 thousand miles of driving actually exceed our tire costs. And believe us, we've found that the quality and performance of our tires has a lot more to do with our driving satisfaction than our fuel does.

We think that much of the misperception has to do with the fact that we buy fuel one tankful at a time, and don't really look at its total cost for thousands of miles. Our tires are paid for "up front" and then last for tens of thousands of miles.

When you are selecting new tires and find one that is perfect, although more expensive than another tire that appears to be a close second, consider evaluating your situation by comparing "how much per mile" each tire will cost. If you plan to drive your vehicle another 30,000 miles and are considering the "perfect" tires at $100 each, and the other at $90 each; you may be surprised to find out that the cost of the "perfect" set costs just 1.3 cents per mile...while the close set costs 1.2 cents per mile. Will saving the $40 today make up for not having selected the "perfect" tire that you will be driving on for the next two years?

The Law

According to most states' laws, tires are legally worn out when they have worn down to 2/32" of remaining tread depth. To help warn drivers that their tires have reached that point, tires sold in North America are required to have molded indicators called "wear bars" across their tread pattern from their outside shoulder to inside shoulder. Wear bars are designed to visually connect the elements of the tire's tread pattern and warn drivers when their tires no longer meet minimum tread depth requirements.

Common Sense

However, as a tire wears it is important to realize that while its dry traction and handling will improve its ability to perform in rain and snow will diminish. At 2/32" of remaining tread depth, resistance to hydroplaning in the rain at highway speeds has been significantly reduced and traction in heavy snow has been virtually eliminated.

If rain and wet roads are a concern, you should consider replacing your tires when they reach approximately 4/32" of remaining tread depth. Since water can't be compressed, you need enough tread depth to allow it to escape through the tire's grooves. If the water can't escape fast enough your vehicle's tires will be forced to hydroplane (actually float) on top of the water, loosing traction.

If snow covered roads are a concern, you should consider replacing your tires when they reach approximately 5/32" of remaining tread depth to maintain good mobility. The reason that you need more tread depth in snow is because your tires need to compress the snow in their grooves and release it as they roll. If there isn't enough tread depth, the "bites" of snow your tires can take on each revolution will be so small that your traction will be reduced. Because tread depth is an important element for snow traction, winter tires start with deeper tread depths than standard all-season or summer tires. Some winter tires even have a series of wear bars molded in their tread pattern indicating approximately 6/32" remaining tread depth.

Original Equipment (OE) Tires

Vehicle manufacturers understand that there is little reason to spend millions of dollars developing the ride and handling qualities of a new vehicle's suspension if they are going to omit integrating the influence of its Original Equipment tires. This has resulted in either completely new tire designs or fine-tuned versions of existing designs being engineered for every new car and light truck from the beginning of the vehicle's development process.

There was a time in America when it was thought that the only reasons a vehicle manufacturer chose Original Equipment tires were "how wide were the whitewalls" and "which manufacturer would sell their bias ply tires for the lowest price." Well even if that had been true, times have changed and neither whitewalls nor cheap bias ply tires are used on vehicles today.

Part of the reason for this is because tire comfort and tire performance directly correlate with the driver's overall vehicle satisfaction. Original Equipment tires play an integral role in achieving the vehicle's desired comfort and performance capabilities, and greatly influence the vehicle's personality. And as vehicles have evolved, so have OE tires. For the most part, today's vehicles are lighter, more fuel-efficient and more responsive than those built a decade ago. This has caused corresponding reductions in tire weight and rolling resistance, while enhancing the tire's handling capabilities.

Unfortunately even the best tires are still a compromise. This is because the current materials and manufacturing technologies that provide many desirable tire attributes are directly opposed to other desirable attributes. For example, a "hard" tread compound that could provide long wear and low rolling resistance would also reduce traction. An "aggressive" tread design that could better resist hydroplaning or provide enhanced snow traction would also generate more noise. And a "stiff" sidewall that could provide responsive handling and high-speed stability would also reduce ride comfort. These opposing goals require blending and balancing the tire's comfort and performance traits until they are optimized for the OE tire's intended vehicle application.

Each vehicle manufacturer prioritizes the areas that they feel are of greatest benefit to help their vehicles satisfy their drivers. For example, a vehicle manufacturer that offers a line of fuel-efficient vehicles may be able to place more emphasis on traction and less emphasis on lowering rolling resistance than a vehicle manufacturer that builds a line of larger, less fuel-efficient cars.

A tire's characteristics can be represented graphically in a "spider" chart (see below). These charts provide a visual means of presenting multiple performance characteristics to allow direct comparison of an existing tire's capabilities (usually established at the 100 level as a baseline) to the targets and/or realized performance levels for a new tire.

While the tire manufacturer's ultimate goal is to develop technology that allows them to expand the new tire's entire comfort and performance envelope in all directions compared to the original tire, frequently they are only able to expand the tire's capabilities in several areas without causing compromises that would result in less performance in other areas. This type of analysis allows confirmation of the accomplished improvements and any resulting compromises.

Starting from the same original tire would result in identifying different goals for a tire intended for a luxury coupe vs. a tire intended for a true sports car. Which is the better tire? In reality, neither of them is better; but they are both different. Most importantly, both would be tuned to meet the desired personality of the car. However, if misapplied, the driver would experience a loss of performance if the luxury coupe tire was installed on the sports car, or a loss of comfort if the sports car tire were installed on the luxury coupe.

Only the vehicle manufacturer and tire manufacturer working together to develop the OE tire can determine exactly which tire design and internal construction will produce the most satisfactory results. A tire manufacturer who builds "all-purpose" replacement tires will never receive the benefit of the vehicle manufacturer's insight and intent, and is relegated to producing "average" tires.

Does It Really Make a Difference?

Since 1990, J.D. Power and Associates has conducted an annual Original Equipment Tire Satisfaction Study to report on how consumers rate their satisfaction with Original Equipment tires on their one-, two- or three-year-old vehicles. The study conducted in 2002 was based on the experiences and opinions of more than 33,700 drivers. The study includes a nationally representative sample of all makes and models of passenger cars, vans, pickup trucks and sport utility vehicles sold in the U.S.

The study monitors consumer perceptions regarding tire quality, performance, brand image and service. Results are calculated using a tire satisfaction index that includes five factors: product quality, long-term performance, situational performance, design and winter traction. The 2002 study found Michelin brand products achieve the highest tire index score with passenger car and light truck drivers.

Maintaining high customer satisfaction is key to vehicle and tire manufacturers alike. Vehicle manufacturers benefit from higher vehicle satisfaction ratings, and tire manufacturers that have high levels of driver satisfaction also have the highest percentage of drivers who report that they intend to buy that same tire brand in the future. Among year-one owners, more than 60 percent of the drivers on OE Michelin report that they plan to repurchase Michelin tires in the future, the highest repurchase intention of all tire brands.

Additionally, the vehicle manufacturers have learned that if the driver is satisfied with their tires they are also likely to be satisfied with their vehicle, increasing their intent to repurchase the same brand of vehicle in the future.

Sidewall Indentations, Undulations & Protrusions

Sidewall Indentations / Undulations

Tire casings are reinforced by multiple fabric cords encased side-by-side in a thin sheet of rubber. Radial ply tires feature one or more layers of cord (depending on the tire's required strength) that run parallel to each other from bead to bead (with each individual cord running up the sidewall, across the tread and down the other sidewall). Because of their "straight across" radial orientation, the overlaps where the sidewall cords are lap-spliced may cause indentations.A common byproduct of radial tire construction, sidewall indentations/undulations are more noticeable in tires with taller sidewalls or operate at higher inflation pressures. Fortunately sidewall indentations are a cosmetic condition that does not affect the performance of the tires.

When the tire is being cured, it is pressed against its metal mold. However when the tire is mounted on a wheel and inflated to operating air pressures, it is free to expand. These overlapping splices may create slight indentations since the stretching capacity of the lap-splices is slightly less than the rest of the body ply. In reality, the splices are the most reinforced area of the tire's sidewall.

Since radial tires feature steel cord reinforcing belts under their treads to keep them flat, indentations only appears on the sidewalls.

Sidewall Protrusions

However if a protruding bulge doesn't appear until later in the tire's life, it was usually the result of a road hazard when several adjacent cords were injured as the tire struck a pothole, curb or object in the road.However, if protruding bulges, as shown at top, rather than indentations appear on the sidewall of a recently installed tire, it reveals that there is an undesirable gap between some of the body ply cords inside the tire. The tire should be removed from service and replaced under the tire manufacturer's materials and workmanship warranty.

Tread Pattern Noise

All tires generate noise as air flows through their tread grooves and they roll into and out of contact with the road. Tire designers have to balance tread design noise with service-appropriate traction, for example, wild looking tread designs that deliver aggressive off-road traction are more likely to growl on the highway, while mild tread designs that offer reduced on-road noise may sacrifice foul weather traction in wet and wintry conditions.

Partnership

Tire noise is dependent on a partnership between the tread pattern and the surface it's driving on.

Roadway surfaces influence both the intensity and spectrum of the sound generated by the tire/surface interaction. Changes in audible sound can often be heard as tires drive from concrete to asphalt roads, or from smooth to coarse surfaces. Spacerless concrete and new asphalt roads tend to be the quietest partners and provide the truest test of the tread pattern noise actually generated by the tires.

If a driver senses new tires generate the same type of noise as their previous tires, it is likely the noise is actually the result of the road surfaces they drive on. While some drivers think their tires are noisy, they may not realize it's the road surface that's actually responsible.

The tire designers' and engineers' goal is to vary audible tones until the tires generate a pleasant "white" noise.

Pitch

The tire industry uses the term pitch to describe the number of tread blocks around the circumference of the tire. As a general rule, summer performance tires feature larger tread blocks and fewer pitches to enhance steering response and handling, while winter tires feature smaller tread blocks and more pitches to increase the number of biting edges that enhance traction in snow and on ice. All-Season tires fall in the middle.

Pitch Sequencing

It's not desirable for all pitches to be created equally. If every tread block (pitch) featured the exact same size and shape, each one would generate the exact same sound tone and intensity as they rolled through contact with the road. This would result in all four tires contributing to an unpleasant monotonous tone.

The tire designers' and engineers' goal is to vary audible tones until the tires generate a pleasant "white" noise.In order to keep that from happening, tire designers use computers to sequence multi-pitch tread designs that subtly vary tread block size and shape to randomize the road contact and resulting noise. They also offset circumferential block placement of neighboring ribs to reduce noise by aligning lateral grooves with adjacent tread blocks.

Preventative Maintenance

Depending on their diameter, tires roll about 800 times per mile. And on every revolution, the leading edge of each independent tread block collides into contact with the road, followed by the rest of the block until the trailing edge is released from contact a fraction of a second later. Happening about 4 million times in just 5,000 miles, this recurring in-and-out-of-road contact has been shown to promote irregular tread wear. If not stopped, irregular wear is likely to change the size and shape of the tread block contact and undo the engineering that made the tire design quiet in the first place.

Since it's important to promote even wear, periodic tire rotation is important preventative maintenance that every tire needs. Periodic tire rotation shares the work and the wear between all of the vehicle's tires and results in non-directional tires rolling in both clockwise and counter-clockwise directions.

Because every tire's tread is its deepest and the most susceptible to irregular wear when new, the first tire rotation is the most important one and must be completed before the tires have been driven 5,000 miles. Unfortunately, as engine oil change intervals have climbed, it's probable the first tire rotation will be required as a stand-alone service.

Tire troubleshooting : Sidewall Separations / Bubbles

Pneumatic tires are made of specialized rubber compounds reinforced by plies of fabric cords and metal wires. While most rubber compounds can be stretched easily, the underlying fabric cords and steel wires actually define the tire's shape by limiting stretching. In order to bond these dissimilar materials, the cords and wires are coated with adhesives and/or rubber before the other components are bonded to them during curing.

A strong bond between these various components is necessary to provide the desired durability. However the strength of the bond can be reduced if 1) any of the components are contaminated during manufacturing (resulting in incomplete bonding), or 2) components are damaged in service due to use while overloaded/underinflated, or by impact with potholes, curbs or other road hazards that pinch the tire between the rim and the road, or simply stretch the rubber beyond the elastic limit of the underlying cords and wires.

Past experience indicates that a sidewall separation/bubble caused by component contamination or incomplete bonding during manufacturing will appear within the first six months of service. Fortunately these separations/bubbles typically appear when they are small in size and before the tire's strength is substantially reduced. However since typical tires roll about 800 times every mile and the air pressure inside the tire is greater than outside, tire separations/bubbles that are unseen or ignored will continue to grow in size, further reduce strength, often generate noise and vibration, and ultimately lead to tire failure as the tire stretches under load (similar to the way that continuously bending a paperclip back and forth will cause it to weaken and break). However there is one last thing to remember; while a separation/bubble early in a tire's life is usually associated with a manufacturing condition, even a single, significant impact with a deep pothole or sharp curb can cause a new tire and wheel to be damaged.

If the sidewall separation/bubble appears after six months of on-vehicle service, prolonged driving on overloaded/underinflated tires or a road hazard are the most likely causes. However it may take weeks or months after an impact for a separation/bubble to appear as the damaged or bruised area continues to weaken. Unfortunately the time differential between the impact that caused the initial damage and the delayed appearance of visible evidence often means that the driver has forgotten about the impact that damaged the tire in the first place.

The varieties of possible causes make it necessary to inspect the tire while mounted on the wheel (sometimes the wheel will show impact damage adjacent to the separation/bubble), as well as to dismount the tire and inspect the condition of its innerliner thoroughly. Sometimes it is necessary to return a tire to the manufacturer's inspection center where it can be dissected before the actual cause can be determined.

While taller profile tires can be damaged by the more severe impacts with deeper potholes and sharper curbs, low profile tires mounted on large diameter wheels are the most susceptible to this type of damage. The driver of vehicles equipped with low profile tires should make special efforts to avoid potholes, curbs or other road hazards.

Tire Warranties

A warranty is a manufacturer's assurance of quality that defines the period of time that they will repair or replace products that show signs of defects due to materials or workmanship. While most consumer goods are backed for their first 30, 60 or 90 days of use or up to one year from the date of purchase, tires (which are subjected to a wider variety of conditions and temperature extremes than other consumer products) are typically backed by their manufacturer's limited warranties for a period of 4 to 6 years from the date of purchase or until the tread wears out, whichever occurs first.

All tires sold by Tire Rack (except race and rally tires) have a manufacturers' limited warranty extended to the original purchaser to cover conditions that are reasonably considered to have been within the tire manufacturers' control, such as the quality of materials and/or workmanship. Selected tires may also be backed by additional warranties, such as tread-wear mileage or free trial periods.

Conversely, none of the limited tire warranties cover conditions that are not considered to have been within the tire manufacturers' control, including irregular wear attributed to a lack of tire maintenance or vehicle condition, damage due to accidents, vandalism or being driven on while flat.

If you have a question about tire warranties or have a tire that you would like to submit for warranty consideration, you can work directly with Tire Rack or with a local dealer that carries that brand of tire.

Warranty Duration

Each manufacturer specifies the duration of their tires' limited warranty in months or years from the date of purchase. Therefore, tire warranties begin at the time of delivery for new vehicles and at the time of purchase for replacement tires. Consequently, a new vehicle's registration certificate or the replacement tire's sales invoice will establish proof of ownership and the tire's in-service date. If no proof of purchase is available, the week and year the tire was manufactured (as identified by the DOT Tire Identification Number (TIN) branded on the sidewall) will be used.

Tire warranties also expire when the tire's original tread is worn down to 2/32" (1.6 mm) of remaining tread at which time the tread blocks are worn flush with the treadwear indicator bars.

"...tires...are typically backed by their manufacturer's limited warranties for a period of 4 to 6 years from the date of purchase or until the tread wears out, whichever occurs first."

Tread/Mileage Warranties

Treadlife/mileage warranties are a popular marketing tool used to help position tires competitively in the marketplace by identifying their potential longevity. However not all consumers will receive the warranted mileage due to the variety of road surfaces, driving conditions and geographic influences across the United States.

Treadlife/mileage warranties typically do not apply to tires fitted as Original Equipment on new vehicles (unless specifically included by the tire manufacturer). Replacement tires covered by a treadlife/mileage warranty have the warranty cost factored into their price.

Treadlife/mileage warranties only apply to the original owner and vehicle upon which the set of tires was initially installed.

Treadlife/mileage warranties are also subject to time limits set by the tire manufacturers and expire along with the standard warranty four, five, or six years from the date of purchase (proof of purchase required).

According to most states' laws, tires become legally worn out when they reach 2/32" of remaining tread depth (identified when the tread blocks/ribs wear down to the bars molded across their tread pattern). Tire manufacturer treadlife/mileage warranties specify pro-rated replacement will only be considered when all four tires reach that point.

Uniformity Warranty

Even though tires are built to tight tolerances, there is bound to be some unavoidable tolerances during the manufacturing process. This is one reason why tire balance and internal forces are measured during a tire's final inspection at the factory.

Note: Because of the factory's final inspection, none of the tire manufacturers will accept that all four tires from the same vehicle are out-of-round or responsible for a vibration. If a request is made to return all four tires, the tire manufacturer will deem that there was no genuine attempt to isolate the true cause of the problem.

The tire manufacturers have identified that if a new tire contributes to a vehicle ride disturbance because of workmanship or materials, it will be apparent immediately and should be diagnosed and corrected as soon as possible. Depending on the manufacturer, the responsible tire must be replaced before the first 1/32" to 2/32" of treadwear or during the first six months/one year of service.

Ride disturbances that occur after this initial period have been linked to road hazard damage or irregular wear stemming from the vehicle's mechanical condition and/or lack of routine maintenance.

Workmanship & Materials Warranty

Tire Manufacturer's Materials and Workmanship Warranty covers conditions that require a tire to be removed from service that are within the tire manufacturers' control of raw materials or quality of workmanship.

Usually during the first year of ownership or 25% of the tire's treadwear (whichever occurs first), the tire will be exchanged free of charge for the customer (not including freight). For the rest of the tire's warranty period, the cost of replacement is prorated by crediting the owner for the percentage of service not received.

Manufacturer Road Hazard Coverage

While road hazard injuries (cuts, punctures, snags and bruises) or impact damage caused by potholes, curbs or other objects in the road are an undesirable part of driving, the tire damage they inflict is not within the control of the tire manufacturer and is not typically covered by their limited tire warranties. Regardless of its quality, no tire is indestructible.

Currently there are a limited number of tires that remain backed by a tire manufacturer road hazard coverage.

However, because many drivers desire the financial security that a road hazard program provides, Tire Rack includes its free Tire Road Hazard Protection with most tires.

Manufacturer Special Warranty - Test Drives/Satisfaction Trials

If a retail customer who purchased eligible tires is not completely satisfied, they can return the tires to the location from which the tires were purchased within the specified period (usually 30-, 45- or 60-days) for exchange for another tire model made by the same manufacturer or, in a few cases, a full refund (freight not included). Original proof of purchase is required.

Tires received as Original Equipment on new vehicles are not covered by tire manufacturers' Test Drives/Satisfaction Trials.

Tire Specs Explained: Maximum Load

Maximum Load

A tire's maximum load is the most weight the tire is designed to carry. Since a tire's load carrying capacity is related to the tire's size and how much inflation pressure is actually used, maximum loads are rated with the tire inflated to an industry assigned inflation pressure.

Additionally, load ranges are used to separate tires that share the same physical size, but differ in strength due to their internal construction. "Higher" load ranges are used to identify tires that have a stronger internal construction, and therefore can hold more air pressure and carry more weight.

Each load range has a assigned air pressure identified in pounds per square inch (psi) at which the tire's maximum load is rated. Listed below are the air pressures at which maximum load is rated for popular P-metric and LT tires:

P-Metric Passenger Vehicle Tires
Load Ranges	Abbreviated	Max Load Pressure
Light Load	(LL)	35 psi (240 kPa)*
Standard Load	(SL)	35 psi (240 kPa)*
Extra Load	(XL)	41 psi (280 kPa)*
*In an effort to internationally harmonize load ratings and ranges, recently introduced and future LL, SL and XL P-Metric sizes will use ISO/Euro-metric maximum load pressures of 36 or 42 psi

Euro-Metric Passenger Vehicle Tires
Load Ranges	Abbreviated	Max Load Pressure
Standard Load	(SL)	36 psi (250 kPa)
Extra Load**	(RF) or (XL)	42 psi (290 kPa)
**Reinforced and Extra Load nomenclature may be used interchangeably to designate heavy-duty tires

LT-Metric and Flotation Light Truck Tires
Load Range	Abbreviated	Max Load Pressure
Load Range B	(LRB)	35 psi (240 kPa)***
Load Range C	(LRC)	50 psi (350 kPa)***
Load Range D	(LRD)	65 psi (450 kPa)***
Load Range E	(LRE)	80 psi (550 kPa)***
Load Range F	(LRF)	95 psi (650 kPa)***
***Industry standards specify selected large LT tire sizes be designed with reduced maximum load pressures

P-metric tires used on passenger cars and station wagons are rated to carry 100% of the load indicated on the tire's sidewall (or listed for the tire in industry load/inflation charts). However, if the same P-metric tires are used on light trucks, (pickup trucks and sport utility vehicles for example), their carrying capacity is reduced to 91% of the load indicated on the tire's sidewall. This reduction in load results in causing light truck vehicle manufacturers to select proportionately larger P-metric sized tires for their vehicles to help offset the forces and loads resulting from a light truck's higher center of gravity and increased possibility of being occasionally "overloaded."

For example, P235/75R15 P-metric sized, standard load tires used on cars and light trucks would be rated to carry the following maximum loads at 35 psi:

Cars	Full Value	2028 lbs.
Light Trucks	9% Reduced Value	1845 lbs.

Additionally, while a tire's maximum load is the most weight the tire is designed to carry, its load carrying capacity at lower inflation pressures is proportional to how much inflation pressure is used. For example, P235/75R15 P-metric sized, standard load (SL) and extra load (XL) tires used on cars would be rated to carry the following loads at the inflation pressures indicated:

Air Pressure (psi)	20	23	26	29	32	35	38	41
P235/75R15 SL	1543	1635	1753	1852	1940	2028
P235/75R15 XL	1543	1635	1753	1852	1940	2028	2105	2183

Note: 35 psi is the assigned "maximum load" pressure for standard load tires and 41 psi is the assigned "maximum load" pressure for extra load tires.

The above chart correctly shows that an extra load tire is not rated to carry any more load than a standard load tire when both are inflated to the same pressure (up to the standard load tire's "maximum load" pressure of 35 psi). This is because a tire's load capacity is a function of its size (which determines the size of the "air chamber"), its construction (which determines how much pressure can be held) and the actual air pressure used (which determines how many air molecules are forced inside the chamber). Tires with equivalent physical dimensions typically carry equivalent loads (until they reach their maximum load pressure).

The tire's maximum load is indicated in relatively small sized print branded near the tire's bead (adjacent to the wheel) indicating the appropriate value. Because tires are global products, their maximum load capacity is branded on the tire in kilograms (kg) and pounds (lb). These values can also be found in the industry's tire load & inflation charts.

Note: P-metric and Euro-metric sized tires' "maximum load" inflation pressure may be, and often are, different that the tire's "maximum inflation pressure."