Numbers on tire size meaning


Tire Size Explained: What the Numbers Mean

Tire size can be confusing. Some numbers on the sidewall are listed in millimeters while others are inches. Plus, the right size for your car, truck, or trailer can differ depending on where and how you drive.

You can see your original equipment tire size in your owner’s manual or on the placard generally located on the driver’s side door jam. This is the sizing recommended by the vehicle manufacturer.

If you’re interested in switching out your tires for a different look or performance, a good place to start is the numbers and other indicators on your existing tires’ sidewall. Next, have a tire professional help you determine a tire size range that will fit your vehicle and driving needs.


Tire Size Meanings

Here’s what those numbers and indicators on the sidewall indicate and how to understand them:

A: TIRE TYPE The first letter in the code tells you what class of tire it is.

P stands for passenger vehicle tire. P-class tires include cars, SUVs, crossovers, minivans and smaller pickup trucks.

LT means light truck tire, designed for vehicles that are capable of carrying heavy loads, towing trailers, or for those looking for an extra heavy duty option. These are often equipped on three-quarter or 1 ton trucks and SUVs.

ST stands for Special Trailer. These tire sizes are meant for trailers, including fifth wheels and other travel trailers, as well as boat and utility trailers.

If there’s no letter before the first number, you have a metric tire most commonly referred to as European size. It’s also measured in millimeters but may have a different load capacity than a P or LT tire.

B: TIRE WIDTH The three-digit number following the letter is the tire’s width (from side to side, looking at the tire head on) in millimeters. This may also be referred to as the section width.

C: ASPECT RATIO The forward slash separates the tire width number from the two-digit aspect ratio. The bigger the aspect ratio, the higher/taller the tire’s sidewall, or “profile” as it’s sometimes called.

The aspect ratio is indicated on the tire sidewall as a percentage. It’s the height of the sidewall measured from wheel rim to top of the tread, expressed as a percentage of tire width.

In this example, the aspect ratio is 65, meaning the sidewall is 65 percent as high as the tire is wide. To get the sidewall height, take the tire width of 215 mm and convert it to inches (8.46). Then multiply this by 65% (.65). This gives you an answer of 5.5, the sidewall height in inches.

D: CONSTRUCTION TYPE This single letter tells you about the internal construction of the tire.

R is for radial tires, the industry standard for most tires today. They have better road grip, lower rolling resistance for better gas mileage, ride comfort and durability than previous generations of tires. In a radial tire, the plies — layers of strong cords made of a blend of polyester, steel and fabric and coated with rubber — are laid perpendicular to the direction of travel.

D is for tires built with diagonal (crisscrossed) plies, called bias-constructed tires. They are also called conventional, x-ply, or cross-ply tires. Some motorcycle and trailer tires still use this internal construction.

Some run-flat tires are identified with an F followed by the type of internal construction.

E: WHEEL DIAMETER This two-digit number specifies wheel diameter in inches. It’s the distance between the two bead seat areas (where a tire gets tightly sealed onto the wheel).

F: LOAD INDEX The two-digit or three-digit number that follows the gap specifies tire load index. The load index symbol indicates how much weight a tire can support, based on the following standard chart. In our example, the load index is 89, which indicates the tire has a load capacity of 1,279 pounds, when inflated to the tire’s maximum air pressure rating.

G: SPEED RATING The last letter is the tire speed rating. This indicates the top speed it’s safe to travel at for a sustained amount of time. A tire with a higher speed rating can handle heat better and provide more control at faster speeds. The maximum operating speed of a vehicle is no more than the lowest speed rating of all tires mounted on the vehicle. (Of course, you should always abide by speed limits for safer driving.) Speed rating is usually, but not always, a single letter (see the chart).


Tire Size Charts

Below you will find several charts that will help you understand tire sizing numbers, including a load index chart and speed rating chart.



Buying New Wheels or Changing Your Tire Size?

A tire size calculator is a quick way to see whether the tire size you’re considering will likely fit your car, SUV, sports car, light truck or crossover.

But remember that is only an estimate. It’s important to stay within the sizing tolerances of your vehicle. Tires that are the wrong size could cause some pull in the steering wheel, rub against the suspension or body of your vehicle, reduce clearance on hills, or result in a stiffer or noisier ride.

If you’re considering mounting a different tire size on your vehicle, check with a tire expert. Find out whether the tires and wheels you have your eye on are the right fit for your vehicle’s suspension, gearing, and bodywork. And ask how any differences in revolutions per mile, tire speed, load index, and speed rating will affect your ride quality and vehicle performance.

See how new tires and rims will look on your car or truck using our Virtual Wheels simulator, available at any Les Schwab.

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Using Load Index & Load Range to Pick the Right Tires

When shopping for tires online, you’ll notice the terms load index, load range, and speed rating included within the technical specifications. (You can find these numbers and letters on your existing tires, located after the size of the tire. ) Understanding the meaning of load index and load range can help you find the right tire for your vehicle and your needs. As always, the experts at Les Schwab can answer all of your questions about what tires are right for you, but in this quick article, we’ll cover some of the basics of these indicators.

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Load Index

The load index of a tire is a number that correlates to the maximum safe carrying capacity of the tire when it’s inflated to its maximum pressure. Higher load index ratings mean your tires will be able to handle a heavier load. In this example, there are two numbers. The higher number (load index) is for single rear-wheel applications. The lower number is for dual-wheel applications. This indicates its load-carrying capacity when inflated to its maximum pressure. Remember, air pressure is what carries the load in a tire. You can find each tire’s carrying capacity with the chart below.


LOAD
INDEX
LOAD
(lbs)
LOAD
INDEX
LOAD
(lbs)
LOAD
INDEX
LOAD
(lbs)
65 639 94 1477 123 3417
66 661 95 1521 124 3527
67 677 96 1565 125 3638
68 694 97 1609 126 3748
69 716 98 1653 127 3858
70 739 99 1709 128 3968
71 761 100 1764 129 4079
72 783 101 1819 130 4189
73 805 102 1874 131 4299
74 827 103 1929 132 4409
75 853 104 1984 133 4541
76 882 105 2039 134 4674
77 908 106 2094 135 4806
78 937 107 2149 136 4938
79 963 108 2205 137 5071
80 992 109 2271 138 5203
81 1019 110 2337 139 5357
82 1047 111 2403 140 5512
83 1074 112 2469 141 5677
84 1102 113 2535 142 5842
85 1135 114 2601 143 6008
86 1168 115 2679 144 6173
87 1201 116 2756 145 6393
88 1235 117 2833 146 6614
89 1279 118 2910 147 6779
90 1323 119 2998 148 6944
91 1356 120 3086 149 7165
92 1389 121 3197 150 7385
93 1433 122 3307    
LOAD INDEX LOAD (lbs)
65 639
66 661
67 677
68 694
69 716
70 739
71 761
72 783
73 805
74 827
75 853
76 882
77 908
78 937
79 963
80 992
81 1019
82 1047
83 1074
84 1102
85 1135
86 1168
87 1201
88 1235
89 1279
90 1323
91 1356
92 1389
93 1433
94 1477
95 1521
96 1565
97 1609
98 1653
99 1709
100 1764
101 1819
102 1874
103 1929
104 1984
105 2039
106 2094
107 2149
108 2205
109 2271
110 2337
111 2403
112 2469
113 2535
114 2601
115 2679
116 2756
117 2833
118 2910
119 2998
120 3086
121 3197
122 3307
123 3417
124 3527
125 3638
126 3748
127 3858
128 3968
129 4079
130 4189
131 4299
132 4409
133 4541
134 4674
135 4806
136 4938
137 5071
138 5203
139 5357
140 5512
141 5677
142 5842
143 6008
144 6173
145 6393
146 6614
147 6779
148 6944
149 7165
150 7385
Load Range (Ply Rating)

On some tires, you’ll see a load range indicator on the sidewall, as shown here. Load Range is an older measure of tire carrying capacity equivalent to ply rating. The ply rating isn’t directly tied to the number of plies used in construction, so we recommend using Load Index when appropriate. Load ranges are arranged in alphabetical order starting with the letter “A”. The ply ratings (load range) combined with the tire size tell you the tire load capacity.

The load range on replacement tires must meet or exceed the recommendation on your vehicle’s door placard or owner’s manual. It can be higher than recommended but never lower.

LOAD RANGE PLY RATING
A 2
B 4
C 6
D 8
E 10
F 12

Les Schwab Tip: Some cars, including electric vehicles, may require tires with a higher load range due to weight with and without passengers.


We’re Your Tire Experts

If this seems confusing. Don’t worry. The pros at Les Schwab will show you all of your options, including the size, load range, and load index you need for work, weekends, or your daily commute.

Tire marking. How to correctly determine tire parameters

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.

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Explanation of tire markings.

195/65 R15 91 T XL

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 take into account when choosing rubber that if you want to put tires with a size of 205/65 R15 instead of the size 195/65 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 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.

Tire load index table:

T is the 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.

Speed ​​index table:

American tire marking:

There are two different American tire markings. 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.

Additional information indicated in the marking on the sidewall of the tire:

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 tire marking M&S (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 icon (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 on which you can continue to drive a car at a speed of no more than 80 km / h with a FULL tire pressure drop (due to a 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 it 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 The temperature resistance of the tire at high speeds on the test bench (A is best).

Traction A, B, or C

Treadwear ; relative expected mileage compared to a specific US standard test.

TWI (Tread Wear Indiration) - tire tread wear indicators. The marking on the TWI wheel can also be with an arrow. Pointers are located evenly in eight or six places around the entire circumference of the tire and show the minimum allowable tread depth. The wear indicator is made in the form of a protrusion with a height of 1.6 mm (the minimum tread value for light vehicles) and is located in the tread recess (usually in the drainage grooves).

DOT - Manufacturer's coded address, tire size code, certificate, issue date (week/year).

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What do the numbers on the tires mean: character interpretation Save article:

In this article:

  1. What do the tire size numbers mean
  2. How to read the American tire label
  3. What important tire parameters are hidden by the numbers
  4. Why tires are color coded

Are you looking for a set of summer or winter tires for your car but don't understand all those numbers and letters? This problem is easily solved. In this article, we will show you how to easily and quickly understand what the numbers on the tires mean, what parameters are hidden behind them, and which tires are suitable for your car.

Only then the car will confidently stay on the road when it is shod with rubber with optimal technical characteristics corresponding to the weather, type of coverage and season.

Tire size: what the numbers mean and how to read them correctly

The marking of car tires consists of several meanings. For example, on any wheel, the manufacturer, brand of rubber, and tire size are indicated. The first three numbers on the wheel indicate the size of the rim (in inches, 1 inch equals 2.54 cm), how wide the tire is, and the height of the profile. This marking can be seen if you look at the wheel from the outside.

Photo: Shutterstock

Let's analyze what the numbers on the tires mean on a specific example of a wheel marked 195 60 R16. The first digit of 195 mm is the tread width. What does the second number on a tire label mean? It shows the relationship between tread height and tire width. The wheel will cling to the coating perfectly if the value of this index is high. Most often, drivers call this parameter the height of the profile.

The last number is the inner diameter of the tire (in inches). Many car owners make the following mistake: they buy tires without taking into account the fact that external parameters change.

So, the height of two wheels marked 185 65 R15 and 210 65 R15 will be different, but the landing diameter is the same. Due to small differences in the profile height and tire width in this example, it will not be possible to mount tires on a car. This should not be forgotten when buying a set of wheels. You can use the tire calculator to find the right tire size for you.

In addition, one more parameter is applied to any wheel, this is the permissible speed. It is located after the numbers on the tires indicating the tire size. This index indicates what maximum speed the tire is designed for.

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What do the numbers on the tires after the speed index mean? Usually there is an indication of the permissible load on one tire. For example, it may look like this: "‎88T"‎. This figure means that when driving at the maximum possible speed of 190 kilometers per hour, the load on one wheel should be no more than 560 kilograms.

What the Tire Numbers Mean in a Case Study

Photo: Shutterstock

To make it clearer what the numbers on the tires mean, consider the European marking of the Cordiant Sport 3 225/65 R17 106H tire model.

What do the numbers on tires made in the USA mean

On American tires, you can find two different types of markings that differ from each other.

Consider the first marking: P 195/60 R 14 or LT 235/75 R15. As you can see, it practically does not differ from the European one. However, the size is preceded by the letter P on passenger tires or LT on tires for light trucks.

There is also a second marking, it looks different: 31x10.5 R15. In this case, the usual European marking would look like this: 265/75 R15. What do the numbers on tires with this marking mean (in inches):

  • 31 - outer diameter of the tire;
  • 5 - the number means the width of the wheel;
  • R - the letter means that the tire has a radial design. The rubber was originally produced with a diagonal construction, but this method of making tires has become obsolete;
  • 15 - this figure means the inner diameter of the tire.

It is worth noting that if you do not pay attention to the units of measurement (inches, which are unusual for us), then the American marking will be clearer and more logical in comparison with the European one. Indeed, in the second case, the height of the rubber profile depends on the width of the wheel.

In the American labeling, everything is simpler. For clarity, consider what the first digit in tire size means. It shows the size, that is, the outer diameter. The second number indicates the width, the third - the inner diameter.

You can follow the current promotions on the Halva Installment Card, which will help you profitably purchase the goods you need, here.

How to find out the width of the tire in the usual units of measurement, that is, in mm? To do this, multiply the width in inches 10.5 by 25.4, because one inch equals 2.54 cm. The result is a value of 267 mm. Since there is no given size, we take into account the width of the tire 265, which is obtained after rounding.

The next step is to find out the height of the sidewall, which is measured as a percentage. To do this, perform the following steps: subtract the bore diameter from the outer diameter. Then we divide the resulting value by 2. The figure that we get, then needs to be divided by the width of the profile.

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"How to choose winter tires and not lose"

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Thus, in our example, we have the following: ((31 - 15) : 2) : 10.5 = 0.76. The resulting value must be rounded up to 75. As a result, we will have the following markings on tires: 265/75 R15.

If the profile height is not indicated on the tire, do not forget that for passenger tires this figure is 80 - 82%, for trucks 88%.

To convert from metric to inch system, we need to perform calculations:

  • We find the diameter, for this you need to multiply the tire width of 265 mm by the profile height of 0.75. Then multiply the resulting value by two. As a result, you will get 397.5. It should be converted to inches (divided by 25.4), and then added to the wheel diameter: 15.6 + 15, you get 30.6. To make it more convenient, you need to round the number up. At the end of the simple math, you will find the diameter of the tire in inches.
  • How to determine tire width in inches? To do this, divide the width in millimeters 265 by 25.4. We get a value of 10.4 inches.

So, we figured out what the numbers on tires with the American marking mean 31 * 10. 5 R15

What does the extra markings and letters on the sidewalls of car tires mean

Photo: Shutterstock

XL or Extra Load - this inscription on the wheels means that they are reinforced, that is, the load index is more than 3 units, compared to standard tires with the same size. Simply put, when you see a load index of 9 on rubber1, as well as the inscription XL, which means that this tire is designed for a load of not 615 kg, but 670. For clarity, it is recommended to study the load index plate.

M+S , M&S ("mud and snow") means that the tires are designed for winter (or all-weather). This marking can also be seen on summer wheels for SUVs. But in this case, rubber is not suitable for use in winter, since winter tires have a different composition, as well as a specific tread pattern. "M&S" means you have an off-road wheel in front of you.

All Season or AS, ("for all weather") - all-weather tires.

The snowflake badge indicates that the tires are designed for winter use. Don't see this marking on the side of the tire? So, you can ride on such tires only in the summer.

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Aquatred, Aquacontact, Rain, Water, Aqua or the symbol "umbrella" - means that you have rain tires in front of you.

Outside and Inside the inscription indicates that these are asymmetrical tires. When installing them on the car, you should be extremely careful, because they have an outer and inner side. During installation, pay attention to the fact that the inscription "Outside" is located outside, "Inside" - from the inside.

RSC, RunFlat - on such rubber, even if a puncture occurs, you can continue driving at speeds up to 80 kilometers per hour. These tires allow you to drive a distance of 50 - 150 km after the pressure has completely dropped. Depending on the manufacturer, the marking may vary slightly, for example Bridgestone RFT, Continental SSR, Goodyear RunOnFlat, Nokian Run Flat, Michelin ZP.

Rotation or the "arrow" icon on the side of the tire means that you have a directional tire in front of you. When mounting it, you should take into account the direction of rotation of the wheel, which is indicated by the arrow.

Tubeless - wheel without a chamber. If there is no such marking, the tire can only be used with a tube. The inscription Tube Type means that rubber can only be used with a camera.

Max Pressure is the highest allowable pressure in the wheel, Max Load is the maximum load capacity (kg) that the tire is designed for.

Reinforced, RF (for example, 195/70 R15RF) means that the tire is reinforced, it has 6 layers. When the letter C is at the end of the marking (for example, 195/70 R15C), which means that this rubber is cargo and it has 8 layers.

Radial The inscription indicates that the tire has a radial construction. If there is the word "Steel", then the tire is reinforced with a metal cord.

Letter E, circled - rubber meets European ECE standards. The inscription DOT means that the tire meets the American quality standard.

Temperature (A, B or C) - shows how rubber is resistant to high temperatures when driving at maximum speed. When the letter A is indicated, then the heat resistance is the best.

Traction (A, B, C) - indicates how well the tire will brake on wet roads.

Treadwear The inscription indicates the relative mileage of the tire.

TWI (Tread Wear Indiration) - means tread wear indicator. Most often, next to this inscription is the sign "arrow". Characters distributed in 6 8 sections all over the wheel. They indicate the smallest tread depth at which the tire is allowed to operate. The wear indicator protrudes 1.6 mm. This is the minimum allowable tread height for passenger tires. The wear indicator is located in a recess in the tread, most often in the grooves to drain water.

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DOT - manufacturer's address code, coded tire size, certificate, and the week and year the tire was manufactured.

What do the colored marks on the tires mean

We have analyzed what the numbers mean on winter tires, as well as on summer and all-season tires. However, in addition to them, there is also a color marking, the meaning of which also needs to be known. Usually on tires you can see various symbols of four colors: red, yellow, white and blue.

Photo: Shutterstock

The most commonly used white label is . For example, you might see icons in a small circle. The white marking is applied by a specialist when checking the compliance of the tire with quality standards. If this symbol is present, it means that the product has been checked by the technical control department.

Red marker can have two meanings. Usually rubber, which has such a marking, is installed at the factory. A small red circle indicates that the tire is the heaviest in this place.

The yellow marker indicates the lightest area of ​​the tire.


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