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If you look closely at any tire, you can find an engraved DOT number. This number gives you valuable insights into the tires keeping you safe. However, it is not always clear to drivers what their DOT number is communicating. The local auto mechanics are here with the full breakdown of how to read a tire’s DOT number.
Every tire identification number begins with the letters DOT (Department of Transportation). It is a marker that verifies you are getting tires that meet the Department of Transportation’s guidelines. It also serves as a clear, universal starting point for a tire’s TIN (tire identification number).
The next group of numbers contains two characters that indicate your tire’s plant code. Every tire manufacturing plant has a unique two-character code, often made with one number and one letter. Why is this important? If there is a tire recall, safety issue, or another tire concern, it can be traced back to the plant that produced the tire(s) in question.
The next two numbers or letters are your tire size code. The tire size code is a little less straightforward than other markings. Originally, the National Highway Traffic Safety Administration (NHTSA) had a universal list of tire sizes and the two-digit codes that represented them. However, the DOT now lets manufacturers determine their own code for tire size, according to the US Federal Register. This change was intended to make it easy for manufacturers to produce new tires without requiring the NHTSA to update its code list. Unfortunately, it makes it challenging to translate the tire size on your tire’s DOT number. Thankfully, there is an easier way to tell your tire size (more on this below).
The third set of values indicates the manufacturer’s characteristics.
It is essentially a space for manufacturers to provide tire distinction or other brand-specific insights. The US Federal Register states, “The third grouping may be used at the manufacturer’s option to provide any other significant characteristics of the tire. Except for cases in which a tire is manufactured for a brand name owner, the third grouping is not required.” Manufacturers then submit their list of codes to the National Highway Traffic Safety Administration.
Much like the tire size code, this grouping often does not provide valuable information for drivers. It is more so used for recalls, errors, and other official identification needs.
Without ever touching the road, a tire can go bad simply due to its age. After 5 years of age, tires begin experiencing thermo-oxidative degradation. This chemical reaction can severely impact tire safety on the road.
The final four digits on your DOT number will tell you the tire’s age. The first two numbers of this grouping indicate the week of the year your tire was manufactured.
The final two digits indicate the year that your tire was manufactured. For example, if your final four DOT numbers are 3020, your tire was manufactured in the 30th week of 2020. You can find more information in our full guide to tire age here.
While DOT numbers are helpful, they might not tell you everything you need to know about your tires. As tire experts, we often have customers ask:
Many drivers expect to find the answers to these and other questions in their DOT number, but this is not the case. Tires brands often include additional insights on the face of the tire. However, it is frequently much easier to view tire information on your tire panel.
If you open your driver’s-side door and turn to face the seat, you will find a sticker against your door frame with information about your tires. You can also find additional details in your owner’s manual.
When you are due for new tires, the mechanics at Chapel Hill Tire are here for you. We proudly serve the greater Triangle area with our 10 locations across Raleigh, Apex, Cary, Durham, Chapel Hill, and Carrboro. Our mechanics also commonly serve nearby areas, including Knightdale, Pittsboro, Wake Forest, Hillsborough, Morrisville, and beyond. You can conveniently buy your new tires online using our Tire Finder tool. For all of your tire services, vehicle services, and car care needs, make an appointment today with your nearest Chapel Hill Tire.
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Are you having difficulties reading the DOT number of your tires? Do you want to know how to read tire date codes? If you have lost the receipt of your purchase, you might be having difficulties knowing the exact age of your tires.
This issue is common and you can find the solution from your tires. Just observe your tires, you will get the answer.
*Picture Copyright: UTires.com
How to Read Tire Date Codes?Whether you are financing your tires or purchasing them, it is important to understand how to read tire date codes. The numbers are present on tires only. You just need to know how to get them. You might have difficulties while reading codes on old tires. Keep reading to know how old your tire is.
Ways to Get Your Tires DOT NumberLook at all the sides of the tires. There are a bunch of numbers and letters. It might seem like a jumble. But this is helpful information about the tire. Find the number that starts with DOT and followed by ten to twelve series. This code will reveal a lot of things about your tires. You will know the tire size, year, and place of the manufacturing with the unique code of the manufacturer. You can also rent a wheel payments to know more about tires.
Once you rent a tire payments, you will not have to be bothered about the manufacturing year. They will take care of this. You just need to look for a rent a wheel return policy to make it more beneficial for you.
Remember that the last four digits of the code are the date the tire was manufactured. You can check the first two digits of the DOT code to know the week of the manufacturing. The last two digits will reveal the manufacturing year. For instance, when it was written in 0203, the manufacturing year was 2003. But it is a bit tricky to know the manufacturing year of tires manufactured before 2000.
Tires Manufactured Before 2000You need to check the last three digits of the DOT code. Check the first two digits to know the week. For instance, when the last three digits read 022, you should understand that the tire was manufactured in the 2nd week of that year. You might be thinking about how to know the year.
The year is the 2nd year of that decade. It is easy to get confused to know the decade. It might be harder to know the exact decade. There might be some other indications to know the year.
*Image Copyright from kilgoretirecenter.com
What About the Incomplete DOT NumbersIncomplete DOT numbers mean the current DOT regulations demand the complete number to be written on one sidewall only. When you find a few digits on the opposite sidewall, you can check the other sidewall to find the complete DOT number.
Reading DOT Tire NumbersNow you know how to read tire date codes. You can simply check at the sidewalls of tires to avoid any further confusion. Also, never lose your purchase receipt. If you do so, you might not get the warranty benefits. So, keep the receipts in a safe place and avoid any confusion by checking the DOT code. Whether you are interested in learning about wheel alignment or more about DOT numbers, our professionals here at Dan the Tire Man can answer your inquiries.
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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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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 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.
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 (corresponding 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 on which you can continue to drive a car at a speed of no more than 80 km / h with a FULL drop in pressure in the tire (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 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).
Traction A, B, or C Tire wet braking capability.
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).
Find tires / tire catalog A lot depends on the right choice of shoes for a car. When deciding to buy a kit, you can be guided by various comparative tests.
However, it is worth remembering that their characteristics must correspond to the operating conditions. In this case, the information indicated in the marking on the sidewall of the tire will help. Such inscriptions on the tire indicate the size of the product and its technological characteristics. Below we will decipher the symbols and try to figure out what the numbers and letters in the rubber marking mean.
We have a wheel with parameters such as 195 60 R16. This means that we have rubber in front of us, with a tread width of 195 mm.
The second number is the ratio of the picture's height to width. The larger this parameter, the more “hooky” the rubber will be. This value is usually referred to as the profile index.
The third number is the inner diameter of the tire in inches. In general, a common mistake is that motorists purchase wheels without paying attention to some data on changes in external parameters. For example, size 185 65 r15 will differ in height from 210 65 r15 with the same bore diameter. The ratio of the profile to the width in our case can interfere with the installation of tires on the car. This factor should be understood and taken into account. And a special calculator will help you correctly calculate the size of the tires.
Tire manufacturers also supply all tires with a speed index without fail. This sign can be found immediately after the wheel size indicator. It tells you how fast you can travel on the roads. A table that deciphers the speed index of passenger car tires will help to read this sign correctly.
| Tire speed classification | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Designation | N | P | Q | R | 9 | S | T | 9 | U | 902U 9022 H | 9 |
| Speed | 140 | 150 | 160 | 170 | 180 | 190 | 200229 | 210 9022E29 9028 240 240 |
Immediately after the speed index on the tires of the car there is an index of the permissible load on each wheel. For example, tire marking contains an indicator of 88t. This indicates that the machine can travel at a maximum speed of 190 km / h, and the maximum allowable load on each wheel is 560 kg.
Certain tires may be marked with the letters XL or the words Reinforced. This marking is usually awarded to tires, the load index of which is higher than standard values.
If the number 88 is written on the sidewall of an xl or extra load tire, then 3 should be added to the value. decipher this indicator as 91 or 615 kg per wheel.
| Number | load in kg one wheel for cars |
|---|---|
| 60-70 | 250-335 |
| 71-80 | 345-450 |
| 81-90 | 462-600 |
| 91-100 | 615-800 |
| 101-110 | 825-1060 |
| 111-120 | 1090-1400 |
| 121-129 | 1450-1850 |
American tire manufacturers resort to a different tire marking. The first one is very similar to the European one, only before the dimension there are additional letters P - passenger, LT - light truck or T - truck.
For example, 185 r14c P means that this is a wheel with a tread width of 185 mm, a diameter of 14 inches and designed for passenger cars.
The second classification system for its products is quite different. If the European system measures the dimensions of car tires in millimeters, then the American system measures in inches. However, it is quite easy to understand. For example, there are numbers on tires 27*11*r15. The first number is the outside diameter of the tire, the second number is the tread width, and the last number is the inside diameter.
To facilitate the mounting of wheels on rims, manufacturers sometimes equip additional color marks that carry their own information. How to decipher such icons - below.
Occasionally, a yellow dot or triangle can be seen on tires, which indicates the lightest spot on the tyre. When mounting, it is necessary to align the mark with the heaviest part of the disc to facilitate balancing.
Additional tire parameters include red circle or triangle symbols that can be found on the sidewall of the rubber. This is the designation of the most rigid place of the tire wall. It must be aligned with the “L” mark on the disc.
A white stamp with a number located on the outer sidewall bears information about the inspector who carried out the final "acceptance" of the goods.
Some tires have radial colored stripes. They help to identify tires of certain brands in the store, quickly look for them in the warehouse. Sometimes the color of the strip indicates the date of issue or the country of manufacture, and also indicates the passage of a run-in.
Many passenger tires have additional markings in addition to the model and tread type designation:
Differs from the inner sides with an asymmetric tread. It will help you figure out which side should be outside when installing a set of rubber on a car;
It is also worth understanding what the seasonal badges on the wheels mean.
