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Once you have determined it’s time to buy tires, you’ll need to know what size tires are correct for your vehicle. Depending on what you drive, you may be interested in how to find the right tire for your…
This information is usually inside your car’s doorjamb, in your owner’s manual. To ensure your current tire or a replacement tire you may be looking at matches your vehicle’s requirements, it will be good for you to understand how tire sizing works. You may have never paid attention to the string of numbers and letters on every tire, but it’s a gold mine of information.
If you’re unsure of how to read tire measurements from your tire walls, the information and graphics below will tell you how to read tire size, understand and interpret it. If you decide you want to substitute a new size or tire type, consult an authorized tire retailer who can expertly advise you, because many optional tire sizes may have different load capacities and could require wheels of a different rim width or diameter and different inflation pressure.
Not sure you need new tires? Our Tire Replacement Guidance article will help you determine whether it’s time to retire your tires.
Most passenger cars, SUVs and light pickups (1/2 ton and smaller) will come with tires that are either P-Metric or Euro-Metric. For P-Metric tires, you’ll see the letter “P” before the number sequence begins: P225/70R16 97H. P-metric is a designation standardized by the Tire and Rim Association for a “passenger car” tire type. For Euro-Metric there will be no preceding letter before the number sequence begins: 225/70R16 98H. Euro-Metric is a designation standardized by the European Tyre and Rim Technical Organization for a “passenger car” tire type.
Both P-Metric and Euro-Metric size tires are designed to primarily be used on passenger vehicles, which can include cars, minivans, SUVs, and other light duty pickup trucks.
If your vehicle is an SUV, Pickup truck or van, you might see a different type of size designation on your placard that is specific for heavy duty light trucks and vans, especially common on ¾ ton and larger pickup trucks and vans. There are two common size types in this category, LT-Metric and Euro-Metric Commercial (aka C-type). Both size types are metric and so use the same structure as P-Metric and Euro-Metric but have some different characters in the size that differentiate them from their passenger car cousins. LT-Metric tires will have the letters “LT” before the size number sequence: LT245/75R17 119/116R Load Range E. Notice that there are two load index numbers and a Load Range, see the section on Load Index for more info. LT-Metric is a designation standardized by the Tire and Rim Association for a “light truck” type tire.
Euro-Metric Commercial or C-Type tires will look very similar to a passenger Euro-Metric size except that there will be a “C” right after the rim size: 23/65R16C 121/119R. Notice that the C-type tires also have two load index numbers. Euro-Metric Commercial, or C-Type is a designation standardized by the European Tyre and Rim Technical Organization for a light truck type tire. Light truck tires are designed to be used on vehicles capable of carrying heavy cargo and are usually only specified by a vehicle manufacturer on vehicles exceeding a certain load capacity.
Other types of tires that fall into the Metric sizing type are Temporary Spares, they start with “T”. If you see a size that starts with “ST,” that means “special trailer” and is only for use on a trailer.
Regardless of whether you are looking at a P-Metric, Euro-Metric, LT-Metric, Euro-Metric Commercial, T or ST tire the numbers in the size mean the same thing.
The first number to appear in your tire size information is the width, in millimeters, of the correct tires for your vehicle: P225/70R16 91S.
Tire width always refers to the measurement from one sidewall to another. Thus, a tire with the measurement “P225” is for a passenger vehicle and has a nominal width of 225 millimeters.
After the slash mark, the next number you see is for the tire’s aspect ratio, which essentially tells you how tall your tire’s profile is: P225/70R16 91S. Aspect ratios are delivered in percentages. Tire makers calculate the aspect ratio by dividing a tire’s height off the rim by its width. If a tire has an aspect ratio of 70, it means the tire’s height is 70% of its width.
Lower aspect ratio tires, such as a 60 series, generally offer vehicle handling performance advantages over higher aspect ratio tires, such as a 75 series, but a typical trade off can be ride harshness.
After the aspect ratio comes a letter that indicates the type of internal construction maintaining your tire’s stability: P225/70R16 91S.
There are two types of construction that you may see on the sidewall of a tire:
Radial tires are the most common tires on the road in the United States today; thus “R” will usually be shown in the tire size designation. Radial construction means the tire’s internal ply cords are oriented in a radial direction, from one bead over to the other, essentially perpendicular to the direction of rotation. You may also occasionally see RF indicating a run flat tire or ZR indicating a tire that is a speed rating higher than V.
The next number is the diameter code, in inches, of the rim onto which the tire can be mounted. For example, a tire with the P225/70R16 91S would fit a rim with a 16-inch diameter.
Load index can be a confusing subject because there are so many different caveats, but we will try to explain everything here.
The next figure after the rim size in the sequence is your tire’s load index, which tells us how much weight, in pounds, the tire can support when fully inflated: P225/70R16 91S
We call it the load “index” because the number doesn’t tell us the precise number of pounds the tire can carry, at least not by itself. However, the number does correspond to a specific load capacity listed in an index. Beginning with 1 and ending with 150, numbers in the load index represent carrying capacities of 99 to 7385 lbs.
There are two types of load types for passenger tires though, Standard Load and Extra Load. If a tire is Standard Load there will be no markings indicating it but if it is Extra Load the letters XL will appear after the size and load index.
Standard Load Euro-Metric: 215/55R17 94V
Extra Load Euro-Metric: 215/55R17 98V XL
Passenger car tires like P-Metric and Euro-Metric will only have one load index number where LT-Metric and Euro-Metric Commercial (C-Type) will have two numbers separated by a slash.
The first number is the load index if the tire is used in a single application, the second number is the load index if the tire is used in a dual application. Passenger type tires cannot be used in a dual application. Light truck tires will also have a Load Range that is indicated by a letter, such as Load Range E. Load Range is an older term that is still commonly used in the industry so you may hear your tire dealer reference it but the load index numbers are the best way to ensure you have the proper tire.
One important but often misunderstood facet about load index is that the load index numbers between standards organizations (P-Metric vs Euro-Metric) are not necessarily on the same scale. Meaning that two tires in the two different systems that have the same load index number could have different maximum load capacities. This is why it’s important to not only look at the load index number but also verify the actual load capacity.
The final figure in a tire size sequence is the speed rating, which is indicated by a letter: P225/70R16 91S.
Just as your load index number corresponds to a specific load, your speed rating letter corresponds to a particular speed capability based on a standardized laboratory test.
For example, a tire with speed rating “S” is rated for up to 112 mph, while a tire rated “R” is up to 106 mph. Remember that this isn’t a recommended cruising speed. Of course, you should always follow legal speed limits on roadways.
Replacement tires must have the same or higher speed rating as the vehicle’s Original Equipment to maintain vehicle speed capability. If a vehicle has tires with different speed ratings, it is the speed rating of the “slowest” tire that dictates the vehicle top speed.
There is one last sizing type that you should know about, especially if you are in the market for off road tires for a light truck or SUV. It’s called a Flotation size and the numbers in this sizing format are very different from the Metric formats.
Flotation sized tires are similar to LT-Metric tires in application except for a few important points. Number one, they cannot be used in dual applications and number two, an equivalent size tire may have different load capacity than its LT-Metric counterpart.
The first number in the Flotation tire size is the overall diameter in inches. Pretty straight forward.
The second number is the section width (sidewall to sidewall) measurement in inches. Again, fairly simple.
After the section width comes a letter that indicates the type of internal construction: 33X12.50R17LT 120Q.
This is the same as is found in the metric sizing systems.
There are two types of construction that you may see on the sidewall of a tire:
Radial tires are the most common tires on the road in the United States today; thus “R” will usually be shown in the tire size designation.
Radial construction means the tire’s internal ply cords are oriented in a radial direction, from one bead over to the other, essentially perpendicular to the direction of rotation.
The next number is the diameter code, in inches, of the rim onto which the tire can be mounted. For example, a tire with the 33X12.50R17LT 120Q would fit a rim with a 17-inch diameter.
The letters LT will be after the Rim Diameter indicating that this tire type is intended for Light Truck vehicles similar to the LT-Metric and Euro-Metric Commercial (C-Type) tires.
Load Index and Speed Rating have the same meaning and format as the tires using the metric sizing system. Note that since flotation tires cannot be used in a dual application there will be only one load index number instead of two.
Another group of stamping on certain types of tires is the Uniform Tire Quality Grading or UTQG. This grading and stamping is required for passenger car tires (i.e. P-metric and Euro-metric) in the all season and summer categories. Dedicated winter tires, Light Truck (LT-Metric, Euro-Metric Commercial, Flotation) and Motorcycle tires are excluded from this requirement.
Quality grading is designed to make the tire purchase decision easier for you. Ideally, the system is intended to provide simple, comparative data so you can make an intelligent buying decision. However, the ratings are based upon test results achieved under special conditions. This means it’s possible to misinterpret the comparative data as it relates to your individual driving habits, conditions, etc. You should still rely on your service or tire professional for assistance.
Quality grading designates the comparative performance levels of a tire based on government-specified tests but commissioned by the individual tire manufacturers.
All tire manufacturers are required to grade regular and all-season passenger tires in three categories:
UTQG
Treadwear
The treadwear grade is a comparative rating based on the wear rate of the tire when tested under controlled conditions on a specified government test course for 6,000 miles (9,600 km). For example, a tire graded 150 would wear one and a half times as well on the government course as a tire graded 100. However actual tire performance depends on driving habits, road characteristics, service practices, and other factors that can influence the outcome.
Traction Grades AA, A, B and C
The traction grades from highest to lowest are AA (the highest), A, B and C. They represent how well tires stop on wet pavement as measured under controlled conditions on specified government test surfaces of asphalt and concrete. C-rated tires will have the lowest traction performance.
WARNING: THE TRACTION GRADE ASSIGNED IS BASED ON A WET BRAKING (STRAIGHT AHEAD) TRACTION TEST AND DOES NOT INCLUDE CORNERING (TURNING) TRACTION.
Temperature Grades A, B and C
The temperature grades A, B, and C represent the tire's resistance to the generation of heat and its ability to dissipate heat when tested under controlled conditions on a specified indoor laboratory test wheel. Sustained high temperature can cause the tire’s material to degenerate and reduce tire life, and excessive temperature can lead to sudden tire failure. The grade C corresponds to a performance level all passenger car tires must meet under the Federal Motor Vehicle Safety Standard No. 109. Grades A and B represent higher levels of performance on the laboratory test wheel than the minimum required by law.
WARNING: THE TEMPERATURE GRADE IS ESTABLISHED FOR A TIRE THAT IS PROPERLY INFLATED AND NOT OVERLOADED. EXCESSIVE SPEED, UNDER INFLATION, OR EXCESSIVE LOADING, EITHER SEPARATELY OR IN COMBINATION, CAN CAUSE HEAT BUILDUP AND POSSIBLE TIRE FAILURE.
DOT Quality Grades
All passenger car tires must conform to other federal requirements in addition to these grades.
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Editor's Note: This article was originally published in August 2021. While our choices are still valid, you may want to check with manufacturers and your tire retailer for updated versions of these tires before buying.
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Getty ImagesBuying new tires can be a daunting experience. You face a bewildering array of brands, sizes and tire types to choose from, so it's easy to be confused. But don't worry: this guide will provide you with the essential facts you need to in order to make the right tire choice for your vehicle at the price you want to pay.
Before you buy, you'll need to know the answers to the following questions:
Already know about tires and just want our top picks? Our favorites in each category are listed below. Further down, you'll find more information about all-season, summer, and winter tires plus our top alternative picks in each category.
Best All-Season Tire
$89 at Amazon
Credit: AmazonBest Summer Tire
$332 at Amazon
Credit: AmazonBest Winter Tire
$307 at Amazon
Credit: AmazonIs our top pick unavailable in the size you need? Looking for a fast, easy way to sort through the dozens of alternatives? Then go to Tire Rack's Tire Decision Guide.
The company says it'll have a list of appropriate alternative choices for you in two minutes or less. The tirerack.com site is also deep with important consumer data, including tire warranties, treadwear guarantees, and tire-test results.
$200 at Amazon$201 at Walmart
Credit: Amazon$138 at Tire Rack
$494 at Amazon
Credit: AmazonThe vast majority of vehicles today come with all-season tires, which are designed to provide acceptable all-around capability throughout the year and in all weather conditions. That means a reasonable ride and respectable handling, quiet running, good wet-weather grip, and some capability in snow. Given their all-season designation, most car owners leave them on in winter and expect that their tires will deliver all the traction they need on snowy, icy roads.
But most all-season tires are marginal in snow; dedicated winter tires, also known as snow tires, provide far better traction when the snow falls.
There are now two main sub-categories of all-season tires: high-performance all-seasons and grand touring all-seasons. High-performance all-season tires provide sharper handling than "standard" all-season tires. They grip the road more confidently and feel more sporty to drive—usually at the expense of some winter-weather traction. These tires are intended for sportier cars and more-aggressive drivers. Grand touring all-season tires have the lower-profile look of high-performance all-season tires but ride better at the price of some handling ability.
Recently, a subset of grand touring all-season tires has emerged that we call “all-weather” tires. These tires feature snow traction that almost comparable to that of pure winter tires while offering similar performance in other areas as conventional all-season tires.
They are designated by a snowflake-within-a-mountain symbol on the tire's sidewall.
$327 at Amazon
Credit: Amazon$255 at Amazon
Credit: Amazon$211 at Tire Rack
This term is a misnomer, as this type of tire should rightly be called "three-season" rubber. Summer tires are designed specifically to deliver dry- and wet-weather traction in moderate or warm weather. They sharpen steering response, increase cornering traction by an order of magnitude, and stop your vehicle in much less distance. But they do so at a cost: most summer tires only work well at temperatures of about 40 degrees Fahrenheit and above. As outside temps fall toward freezing, the tires can feel skittish and behave inconsistently; they lose a large portion of their grip to the point that they act like they are on a wet or even icy road.
More than one driver of a powerful car, unaware of the temperature sensitivity of its summer tires, has lost control and crashed on a cold day.
As with all-season tires, summer rubber comes in several varieties. Tire Rack divides these tires into three main groups by escalating capability: ultra-high performance on the bottom rung, followed max performance and extreme performance. Summer tires come on cars such as Porsches, Corvettes, Mercedes-AMGs, and Mustangs.
Winter TiresNow 15% Off
$141 at Amazon$183 at Walmart
Credit: Amazon$208 at Amazon
Credit: Amazon$476 at Amazon
Credit: AmazonCalled "snow tires" in the past, winter tires are designed to provide maximum traction in snow and in slippery winter conditions—and the traction they provide in those situations is not matched by any other category of tire.
Even an all-wheel-drive vehicle on all-season tires cannot match the stopping or turning capability of a similar two-wheel drive vehicle fitted with four winter tires, a point we have proven in our own winter-tire testing.
Winter tires are designed to work well in the cold-weather months, but they don't handle or wear as well as all-season or summer tires once the weather warms up. They should be considered as a second set of tires for your vehicle if you live where snow flies annually. We fit all of our long-term test vehicles with winter tires and they've proven their worth many times over.
Why use winter tires? If you live in the northern states, we recommend purchasing a set of winter tires. Their deep treads are engineered to deliver a significant traction improvement, and do they ever work. You'll feel safer and be safer, not to mention more relaxed when driving in snow. Retailers such as Tire Rack will sell you a set of snows mounted on steel wheels that you can swap on when winter rolls around.
Here at Car and Driver, we swear by them.
Tire Size and Other Factors
Most consumers choose to replace the worn tires on their vehicle with something equivalent in size and capability. This makes a lot of sense; your car was engineered to work well on the type and size of tires it came on, so fitting an identical or similar replacement set would maintain the performance and safety your vehicle was designed to deliver. (We'll get to upgrading later on).
To inform your decision process, you'll need to know your vehicle's tire size and speed rating, and you'll also want to consider how many miles you'll get out of any new tires you are considering (this is called tread wear). Much of that information is printed on the sidewalls of the tires that are on your car right now.
It's also available in most owner's manuals, online, and at tire dealers. (We suggest cross-checking those sources to make sure you've got the right information.)
Here's how to read the most important data imprinted on your tires' sidewalls. (For an in-depth look at how to read all of the information on a tire sidewall, click here.)
KEY: 1) Tire width; 2) Aspect ratio; 3) Radial-tire designation; 4) diameter; 5) Load rating with speed rating; 6) Heaviest spot on tire; 7) Tread-wear rating; 8-9) Traction and temperature ratings; 10-11) Mud-and-snow or three-peak-mountain rating; 12) Vehicle-specific marking; 13) Tire-materials list and manufacturing information
Tire SizeIf you're going to replace your tires with something equivalent, you will need to know the proper size. The size of car and light truck tires is usually expressed in a short series of numbers and letters that read like this (as seen in the above illustration): 245/40-R18.
The first number indicates the width of the tire at its widest point in millimeters. The number after the slash is what's called the aspect ratio, which indicates how tall the sidewall is as a percentage of the width. The higher the number, the taller the sidewall. The squat tires fitted to sports cars and muscle cars, called low-profile tires, have aspect ratios of 30–40. Family sedans and SUVs are in the 45-60 range or taller. The final number in the series is the diameter of the wheel in inches that the tire must mount to. The "R" indicates it's a radial tire, which virtually all of today's tires are.
Tires also carry a speed rating, which indicates not only how fast they can safely go for an extended period of time, but also the overall performance potential of the tires. Tires for high-performance cars have a higher speed rating than those for mainstream family sedans and SUVs. The speed rating of the original tires that came on your car were matched to the maximum speed the car could attain—plus a significant built-in safety margin.
This speed rating is expressed as a letter in the alpha-numeric code that immediately follows the tire size. Letters range from L to Y, and cover maximum speed ranges from 75 mph to more than 186 mph.
The are two pieces of data that will help you estimate how many miles you can expect from a set of tires: the tread-wear rating and the tire mileage warranty. The tread wear rating is listed as a number on the tire sidewall after the word "treadwear". The higher this number, the more likely the tire will last longer. But the tests that are used to determine treadwear aren't precise, so there is a lot of variability in this number.
A better way to gauge potential tire life, and to compare the expected longevity of different tires you might be considering, is to look at the manufacturers' tread-life warranties. Many but not all tires carry a tread-life warranty in addition to manufacturing-quality/defect warranties.
This information can be found online (like this example from tirerack.com), or in the tire maker's marketing materials. The industry's general rule is that about three-quarters of all drivers will find that their tires last at least last as long as the mileage listed in the tread life warranty. Generally, if your tires wear out before the guaranteed mileage bogey, you can get a credit for the percentage of miles you came up short, which you can then apply to the purchase of a new tire. (Tire dealers routinely handle this transaction.)
Numerous automakers fit their cars with run-flat tires from the factory. These tires are capable of driving for short distances at low speeds even after a puncture has left them without air, allowing you to reach home or a repair facility without needing to change a flat on the side of the road. If your vehicle came on run-flats you have the option of replacing them with conventional tires and carrying a spare (but beware that some cars fitted with run-flats actually do not have a trunk compartment for a spare).
Or, you can replace your worn run-flats with another set of run-flats. And now that tire-pressure monitoring systems are compulsory equipment in new cars, you could even fit run-flats on a car that didn’t originally come with them.
Run-flat tires do have downsides. Their stiff sidewalls, which are required to hold the tire up when deflated, tend to make the car ride noticeably harder over rough pavement, but tire tech is continually improving and run-flats aren’t nearly the penalty they were a decade ago. Choice is also more limited than with conventional tires and run-flats are premium-priced. In general, we'd recommend swapping to conventional tires and carrying a spare or mini-spare if possible.
There's one more decision you need to make: do you simply replace the tires on your vehicle with something equivalent, or upgrade?
If you're going to replace what came on the car with something equivalent, you're ready to go.
Peruse the online resources like Tire Rack to compare tires, and then either buy from one of them or head to a local tire store. The advantage of buying online is that you can get the exact tires you want; different brick-and-mortar tire stores sell different brands of tires. The online retailers have relationships with the chain tire stores, which will mount the tires you bought on the internet on your wheels (for a small fee) even though you didn't buy them there. Tire Rack has a decision guide to help you find the tires that fit your car.
This is more complicated than simply replacing your tires, as you have several ways to go. You can choose a higher-performance tire of the same size on your current set of wheels by substituting, say, a high-performance all-season tire for a standard all-season—if you can find one that fits exactly. Or you can choose a set of wider, lower-profile summer or high-performance all-season tires, but this is trickier.
You need to know if the tires will fit without rubbing on the suspension or body parts—a definite safety issue. Here, consulting one of the experts at Tire Rack is a must, as they have this information for many cars. You can also try checking an online forum for your make and model of car (if one exists).
Many vehicles can be had from the factory with several different tire sizes—Honda Civics, for example, come with tires ranging from 215/55-R16 to 245/30ZR-20—so going to a larger-diameter wheel might work. But know that fitting lower-profile rubber will almost always require a larger-diameter wheel. The outside diameter of your tires needs to remain constant; everything from your vehicle's suspension to its ground clearance to its gearing is affected by the overall size of the tires. As the sidewall gets slimmer, the wheel must grow to compensate. Use this size guide to see how switching to a lower-profile tire affects wheel diameter.
Wider, lower-profile higher-performance tires can also make the car ride rougher, wear faster, be noisier, and influence the steering, possibly causing you to have to make more steering corrections on the Interstate.
Low-profile tires will also probably be more prone to damage from potholes, something we experienced with one of our long-term cars, which blew out a dozen of its low-profile tires in the course of 40,000 miles on our rutted Michigan roads. And they'll almost definitely be more expensive, plus you'll have to buy a new set of wheels. You'll need to consider all of these issues carefully before you make the leap.
For everything you need to know about buying and maintaining tires, click here.
Rich Ceppos
Director, Buyer's Guide
Rich Ceppos has evaluated automobiles and automotive technology during a career that has encompassed 10 years at General Motors, two stints at Car and Driver totaling 19 years, and thousands of miles logged in racing cars. He was in music school when he realized what he really wanted to do in life and, somehow, it's worked out. In between his two C/D postings he served as executive editor of Automobile Magazine; was an executive vice president at Campbell Marketing & Communications; worked in GM's product-development area; and became publisher of Autoweek.
He has raced continuously since college, held SCCA and IMSA pro racing licenses, and has competed in the 24 Hours of Daytona. He currently ministers to a 1999 Miata and a 1965 Corvette convertible and appreciates that none of his younger colleagues have yet uttered "Okay, Boomer" when he tells one of his stories about the crazy old days at C/D.
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How to find out the correct tire size for your car?
29.06.2019
Author: Sergey Akhmetov
Views: 37693
If you don't know what size of tires should be on your car or are not sure that the size recommended by the manufacturer is currently installed on it, then you are at the right place.
Here is 7 ways to find out the correct tire size for your car:
1. View the size on the sidewall of the tire that is currently installed on the car
You can read how it looks and how to read the designations on tires correctly in our article “Tyre marking: basic parameters”.
This method is suitable if you know that the car has factory tires or that the car is still under warranty. Otherwise, read on.
2. See the recommended tire sizes depending on the car model:
- on the inside of the glove compartment
- on the end part of the driver's door
- on the side of the car
- on the inside of the gas tank hatch
3. Look at the operating manual of your car
as As a rule, the relevant section (Chassis, Tires / Wheels, etc.) contains information on the permissible rubber sizes.
4. Look at the website of the car manufacturer or its dealer
This method may suit you if the car is still being produced and sold. In this situation, data on the sizes of tires and wheels, as a rule, is contained in the "Technical Specifications" or "Car Equipment" section.
5. Call the official service that serves your brand of car
other car.
The same applies to absolutely new models on the market - especially Chinese ones. Sometimes, except for the "officials", no one knows what tires and wheels can be put on them.
6. Use the selection of tires by car brand
Specialized online stores have the service "Selection of tires by car brand", which allows you to immediately determine by manufacturer, model, year and engine size which tire sizes and for which diameter can be put on the car. Here you can see not only your factory size, but also alternative options, if, for example, there is a need to switch to smaller / larger diameter rims, install tires of different widths, etc.
7. Find information on the forum of the owners of your car model
It is often on the forums of car owners that you can quickly find all the necessary information not only on tires, but also on many other issues. People there, as a rule, are active and ready to share various kinds of information with like-minded people.
Whatever method you choose for yourself, it is important to understand that the correct size of tires on a vehicle is:
We also recommend that you always consult a competent person before installation. Our managers are always ready to help you in solving a variety of issues.
If you managed to decide on the correct tire size, then we suggest proceeding to the next step - Choosing tires.
Contents
Do you want to choose a tire for your car, but do not understand tire markings well? It's not a problem! In this section, we will help you figure out what tire parameters are, what they mean, and which tire is right for your car.
195/65 R15 91 TXL
195 is the tire width in mm.
65 - Proportionality, i.e. profile height to width ratio. In our case, it is equal to 65%. Simply put, with the same width, the larger this indicator, the higher the tire will be and vice versa. Usually this value is simply called “profile”.
Since the tire profile is a relative value, it is important to consider when choosing rubber that if you instead of size 195/65 R15, if you want to put tires with a size of 205/65 R15, then not only the width of the tire will increase, but also the height! Which in most cases is unacceptable! (except when both of these sizes are indicated in the car's operating book). You can calculate the exact data on changing the outer dimensions of the wheel in a special tire calculator.
If this ratio is not specified (for example, 185/R14C), then it is equal to 80-82% and the tire is called full profile.
Reinforced tires with this marking are usually used on minibuses and light trucks, where a large maximum wheel load is very important.
R - means a tire with a radial cord (in fact, almost all tires are made this way now).
Many mistakenly believe that R- means the radius of the tire, but this is precisely the radial design of the tire. There is also a diagonal design (indicated by the letter D), but recently it has practically not been produced, since its performance is noticeably worse.
15 - wheel (rim) diameter in inches. (It is the diameter, not the radius! This is also a common mistake). This is the “landing” diameter of the tire on the disk, i.e. is the inside size of the tire or the outside of the rim.
91 - load index. This is the level of maximum permissible load on one wheel. For passenger cars, it is usually done with a margin and is not a decisive factor when choosing tires (in our case, IN - 91 - 670 kg.
). For minibuses and small trucks, this parameter is very important and must be observed.
T - tire speed index. The larger it is, the faster you can ride on this tire (in our case, IS - H - up to 210 km / h). Speaking about the tire speed index, I would like to note that with this parameter, the tire manufacturer guarantees the normal operation of the rubber when the car is constantly moving at the specified speed for several hours.
There are two different markings for American tires. The first one is very similar to the European one, only the letters “P” (Passanger - for a passenger car) or “LT” (Light Truck - light truck) are placed before the size. For example: P 195/60 R 14 or LT 235/75 R15. And another tire marking, which is fundamentally different from the European one.
Example: 31x10.
5 R15 (corresponds to European size 265/75 R15)
31 is the outside diameter of the tire in inches.
10.5 is tire width in inches.
R - a tire with a radial design (older tire models were with a diagonal design).
15 is the inner diameter of the tire in inches.
Generally speaking, except for inches that are unusual for us, the American tire marking is logical and more understandable, unlike the European one, where the height of the tire profile is not constant and depends on the width of the tire. And here everything is simple with decoding: the first digit of the standard size is the outer diameter, the second is the width, the third is the inner diameter.
XL or Extra Load is a reinforced tire, the load index of which is 3 units higher than that of conventional tires of the same size.
In other words, if a given tire has a load index of 91 marked XL or Extra Load, then this means that with this index, the tire is able to withstand a maximum load of 670 kg instead of 615 kg (see the table of tire load indices).
M+S or M&S tire marking (Mud + Snow) - mud plus snow and means that the tires are all-season or winter. Many summer tires for SUVs are labeled M&S. However, these tires must not be used in winter, as winter tires have a completely different rubber compound and tread pattern, and the M&S badge indicates good flotation performance.
All Season or AS all season tires. Aw (Any Weather) - Any weather.
Pictogram * (snowflake) — rubber is designed for use in harsh winter conditions. If this marking is not on the sidewall of the tire, then this tire is intended for use only in summer conditions.
Aquatred, Aquacontact, Rain, Water, Aqua or pictogram (umbrella) - special rain tires.
Outside and Inside ; asymmetric tires, i.e. It is important not to confuse which side is the outside and which is the inside. When installing, the Outside inscription must be on the outside of the car, and Inside on the inside.
RSC (RunFlat System Component) - RunFlat Tires are tires that allow you to continue driving your vehicle at a maximum speed of 80 km/h with a FULL tire pressure drop (puncture or cut). On these tires, depending on the manufacturer's recommendations, you can drive from 50 to 150 km. Different tire manufacturers use different designations for RSC technology. For example: Bridgestone RFT, Continental SSR, Goodyear RunOnFlat, Nokian Run Flat, Michelin ZP etc.
Rotation or arrow This marking on the tire sidewall indicates a directional tire. When installing the tire, you must strictly observe the direction of rotation of the wheel, indicated by the arrow.
Tubeless - tubeless tire.
In the absence of this inscription, the tire can only be used with a camera. Tube Type - indicates that this tire must be used only with a tube.
Max Pressure ; maximum allowable tire pressure. Max Load - the maximum allowable load on each wheel of the car, in kg.
Reinforced or the letters RF in the size (for example 195/70 R15RF) means that this is a reinforced tire (6 layers). The letter C at the end of the size (for example 195/70 R15C) indicates a truck tire (8 layers).
Radial this marking on the rubber in the standard size means that this is a radial construction tire. Steel means that there is a metal cord in the tire structure.
Letter E (in a circle) - the tire meets the European requirements of ECE (Economic Commission for Europe). DOT (Department of Transportation - US Department of Transportation) is an American quality standard.
Temperature A, B, or C Temperature resistance of the tire at high speeds on the test bench (A is best).
