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How to Read Speed Rating, Load Index & Service Descriptions
Using a P195/60R15 87S tire size as our example, the 87S at the end of the size represents the tire's service description. A service description identifies the tire's load index and speed rating. Service Descriptions are required on all speed rated (except for Z-speed rated) tires manufactured since 1991.
The first two digits (87S) represent the tire's load index and are followed by a single letter (87S) identifying the tire's speed rating.
Load Index
P195/60R15 87S - The load index (87) is the tire size's assigned numerical value used to compare relative load carrying capabilities. In the case of our example the 87 identifies the tires ability to carry approximately 1,201 pounds.
The higher the tire's load index number, the greater its load carrying capacity.
89 = 1,279 pounds
88 = 1,235 pounds
87 = 1,201 pounds
86 = 1,168 pounds
85 = 1,135 pounds
A tire with a higher load index than that of the Original Equipment tire indicates an increase in load capacity. A tire with a load index equal to that of the Original Equipment tire indicates an equivalent load capacity. A tire with a lower load index than the Original Equipment tire indicates the tire does not equal the load capacity of the original.
Typically, the load indexes of the tires used on passenger cars and light trucks range from 70 to 110.
Speed Rating
In Germany some highways do not have speed limits and high speed driving is permitted. Speed ratings were established to match the speed capability of tires with the top speed capability of the vehicles to which they are applied. Speed ratings are established in kilometers per hour and subsequently converted to miles per hour (which explains why speed ratings appear established at "unusual" mile per hour increments). Despite the tire manufacturer's ability to manufacturer tires capable of high speeds, none of them recommend the use of their products in excess of legal speed limits. The maximum operating speed of a vehicle must be limited to the lowest speed rated tire on the vehicle.
Speed ratings are based on laboratory tests where the tire is pressed against a large diameter metal drum to reflect its appropriate load, and run at ever increasing speeds (in 6.2 mph steps in 10 minute increments) until the tire's required speed has been met.
It is important to note that speed ratings only apply to tires that have not been damaged, altered, under-inflated or overloaded. Additionally, most tire manufacturers maintain that a tire that has been cut or punctured no longer retains the tire manufacturer's original speed rating, even after being repaired because the tire manufacturer can't control the quality of the repair.
Over the years, tire speed rating symbols have been marked on tires in any of three ways shown in the following examples:
Each of these was an acceptable method of identifying speed ratings.
Early tires had their speed rating symbol shown "within" the tire size, such as 225/50SR16. Tires using this type of branding were not to have been produced after 1991.
Beginning in 1991, the speed symbol denoting a fixed maximum speed capability of new tires must be shown only in the speed rating portion of the tire's service description, such as 225/50R16 89S. The most common tire speed rating symbols, maximum speeds and typical applications are shown below:
When Z-speed rated tires were first introduced, they were thought to reflect the highest tire speed rating that would ever be required, in excess of 240 km/h or 149 mph. While Z-speed rated tires are capable of speeds in excess of 149 mph, how far above 149 mph was not identified. That ultimately caused the automotive industry to add W- and Y-speed ratings to identify the tires that meet the needs of new vehicles that have extremely high top-speed capabilities.
While a Z-speed rating still often appears in the tire size designation of these tires, such as 225/50ZR16 91W, the Z in the size signifies a maximum speed capability in excess of 149 mph, 240 km/h; the W in the service description indicates the tire's 168 mph, 270 km/h maximum speed.
Most recently, when the Y-speed rating indicated in a service description is enclosed in parentheses, such as 285/35ZR19 (99Y), the top speed of the tire has been tested in excess of 186 mph, 300 km/h indicated by the service description as shown below:
As vehicles have increased their top speeds into Autobahn-only ranges, the tire speed ratings have evolved to better identify the tires capability, allowing drivers to match the speed of their tires with the top speed of their vehicle.
======================================================
Determining the Age of a Tire
When it comes to determining the age of a tire, it is easy to identify when a tire was manufactured by reading its Tire Identification Number (often referred to as the tire’s serial number). Unlike vehicle identification numbers (VINs) and the serial numbers used on many other consumer goods (which identify one specific item), Tire Identification Numbers are really batch codes that identify the week and year the tire was produced.
The U.S. Department of Transportation (DOT) National Highway Traffic Safety Administration (NHTSA) requires that Tire Identification Numbers be a combination of the letters DOT, followed by ten, eleven or twelve letters and/or numbers that identify the manufacturing location, tire size and manufacturer's code, along with the week and year the tire was manufactured.
Tires Manufactured Since 2000
Since 2000, the week and year the tire was produced has been provided by the last four digits of the Tire Identification Number with the 2 digits being used to identify the week immediately preceding the 2 digits used to identify the year.
Example of a tire manufactured since 2000 with the current Tire Identification Number format:
[TABLE="width: 95%"]
[TR]
[TD]DOT U2LL LMLR 5107[/TD]
[TD][/TD]
[/TR]
[TR]
[TD] 51[/TD]
[TD]Manufactured during the 51[SUP]st [/SUP]week of the year[/TD]
[/TR]
[TR]
[TD]07[/TD]
[TD]Manufactured during 2007[/TD]
[/TR]
[/TABLE]
While the entire Tire Identification Number is required to be branded onto one sidewall of every tire, current regulations also require that DOT and the first digits of the Tire Identification Number must also be branded onto the opposite sidewall. Therefore, it is possible to see a Tire Identification Number that appears incomplete and requires looking at the tire’s other sidewall to find the entire Tire Identification Number
The use of a partial Tire Identification Number on the one sidewall (shown above) reduces the risk of injury to the mold technician that would have to install the weekly date code on the top sidewall portion of a hot tire mold.
Tires Manufactured Before 2000
The Tire Identification Number for tires produced prior to 2000 was based on the assumption that tires would not be in service for ten years. While they were required to provided the same information as today’s tires, the week and year the tire was produced was contained in the last three digits. The 2 digits used to identify the week a tire was manufactured immediately preceded a single digit used to identify the year.
Example of a tire manufactured before 2000 with the earlier Tire Identification Number format:
[TABLE="width: 95%"]
[TR]
[TD]DOT EJ8J DFM 408[/TD]
[TD][/TD]
[/TR]
[TR]
[TD] 40[/TD]
[TD]Manufactured during the 40[SUP]th[/SUP] week of the year[/TD]
[/TR]
[TR]
[TD]8[/TD]
[TD]Manufactured during the 8[SUP]th[/SUP] year of the decade[/TD]
[/TR]
[/TABLE]
While the previous Tire Identification Number format identified that a tire was built in the 8th year of a decade, there was no universal identifier that confirmed which decade (tires produced in the 1990s may have a small triangle following the Tire Identification Number to identify the decade).
And finally, hold on to your sales receipt. Most tire manufacturer's warranties cover their tires for four years from the date of purchase or five years from the week the tires were manufactured. So if you purchase new tires that were manufactured exactly two years ago they will be covered for a total of six years (four years from the date of purchase) as long as you have your receipt. If you lose your receipt, your tires' warranty coverage will end five years from the week the tire was produced (resulting in the tire manufacturer's warranty coverage ending only three years from the date of purchase in this example).
How to Read Speed Rating, Load Index & Service Descriptions
Using a P195/60R15 87S tire size as our example, the 87S at the end of the size represents the tire's service description. A service description identifies the tire's load index and speed rating. Service Descriptions are required on all speed rated (except for Z-speed rated) tires manufactured since 1991.
The first two digits (87S) represent the tire's load index and are followed by a single letter (87S) identifying the tire's speed rating.
Load Index
P195/60R15 87S - The load index (87) is the tire size's assigned numerical value used to compare relative load carrying capabilities. In the case of our example the 87 identifies the tires ability to carry approximately 1,201 pounds.
The higher the tire's load index number, the greater its load carrying capacity.
89 = 1,279 pounds
88 = 1,235 pounds
87 = 1,201 pounds
86 = 1,168 pounds
85 = 1,135 pounds
A tire with a higher load index than that of the Original Equipment tire indicates an increase in load capacity. A tire with a load index equal to that of the Original Equipment tire indicates an equivalent load capacity. A tire with a lower load index than the Original Equipment tire indicates the tire does not equal the load capacity of the original.
Typically, the load indexes of the tires used on passenger cars and light trucks range from 70 to 110.
| Load Index | Pounds | Kilograms | Load Index | Pounds | Kilograms | |
| 71 | 761 | 345 | 91 | 1356 | 615 | |
| 72 | 783 | 355 | 92 | 1389 | 630 | |
| 73 | 805 | 365 | 93 | 1433 | 650 | |
| 74 | 827 | 375 | 94 | 1477 | 670 | |
| 75 | 853 | 387 | 95 | 1521 | 690 | |
| 76 | 882 | 400 | 96 | 1565 | 710 | |
| 77 | 908 | 412 | 97 | 1609 | 730 | |
| 78 | 937 | 425 | 98 | 1653 | 750 | |
| 79 | 963 | 437 | 99 | 1709 | 775 | |
| 80 | 992 | 450 | 100 | 1764 | 800 | |
| 81 | 1019 | 462 | 101 | 1819 | 825 | |
| 82 | 1047 | 475 | 102 | 1874 | 850 | |
| 83 | 1074 | 487 | 103 | 1929 | 875 | |
| 84 | 1102 | 500 | 104 | 1984 | 900 | |
| 85 | 1135 | 515 | 105 | 2039 | 925 | |
| 86 | 1168 | 530 | 106 | 2094 | 950 | |
| 87 | 1201 | 545 | 107 | 2149 | 975 | |
| 88 | 1235 | 560 | 108 | 2205 | 1000 | |
| 89 | 1279 | 580 | 109 | 2271 | 1030 | |
| 90 | 1323 | 600 | 110 | 2337 | 1060 |
Speed Rating
In Germany some highways do not have speed limits and high speed driving is permitted. Speed ratings were established to match the speed capability of tires with the top speed capability of the vehicles to which they are applied. Speed ratings are established in kilometers per hour and subsequently converted to miles per hour (which explains why speed ratings appear established at "unusual" mile per hour increments). Despite the tire manufacturer's ability to manufacturer tires capable of high speeds, none of them recommend the use of their products in excess of legal speed limits. The maximum operating speed of a vehicle must be limited to the lowest speed rated tire on the vehicle.
Speed ratings are based on laboratory tests where the tire is pressed against a large diameter metal drum to reflect its appropriate load, and run at ever increasing speeds (in 6.2 mph steps in 10 minute increments) until the tire's required speed has been met.
It is important to note that speed ratings only apply to tires that have not been damaged, altered, under-inflated or overloaded. Additionally, most tire manufacturers maintain that a tire that has been cut or punctured no longer retains the tire manufacturer's original speed rating, even after being repaired because the tire manufacturer can't control the quality of the repair.
Over the years, tire speed rating symbols have been marked on tires in any of three ways shown in the following examples:
| 225/50SR16 | 225/50SR16 89S | or 225/50R16 89S |
Each of these was an acceptable method of identifying speed ratings.
Early tires had their speed rating symbol shown "within" the tire size, such as 225/50SR16. Tires using this type of branding were not to have been produced after 1991.
| 225/50SR16 | 112 mph, 180 km/h |
| 225/50HR16 | 130, 210 km/h |
| 225/50VR16 | in excess of 130 mph, 210 km/h |
Beginning in 1991, the speed symbol denoting a fixed maximum speed capability of new tires must be shown only in the speed rating portion of the tire's service description, such as 225/50R16 89S. The most common tire speed rating symbols, maximum speeds and typical applications are shown below:
| L | 75 mph | 120 km/h | Off-Road & Light Truck Tires |
| M | 81 mph | 130 km/h | Temporary Spare Tires |
| N | 87 mph | 140km/h | |
| P | 93 mph | 150 km/h | |
| Q | 99 mph | 160 km/h | Studless & Studdable Winter Tires |
| R | 106 mph | 170 km/h | H.D. Light Truck Tires |
| S | 112 mph | 180 km/h | Family Sedans & Vans |
| T | 118 mph | 190 km/h | Family Sedans & Vans |
| U | 124 mph | 200 km/h | |
| H | 130 mph | 210 km/h | Sport Sedans & Coupes |
| V | 149 mph | 240 km/h | Sport Sedans, Coupes & Sports Cars |
When Z-speed rated tires were first introduced, they were thought to reflect the highest tire speed rating that would ever be required, in excess of 240 km/h or 149 mph. While Z-speed rated tires are capable of speeds in excess of 149 mph, how far above 149 mph was not identified. That ultimately caused the automotive industry to add W- and Y-speed ratings to identify the tires that meet the needs of new vehicles that have extremely high top-speed capabilities.
| W | 168 mph | 270 km/h | Exotic Sports Cars |
| Y | 186 mph | 300 km/h | Exotic Sports Cars |
While a Z-speed rating still often appears in the tire size designation of these tires, such as 225/50ZR16 91W, the Z in the size signifies a maximum speed capability in excess of 149 mph, 240 km/h; the W in the service description indicates the tire's 168 mph, 270 km/h maximum speed.
| 225/50ZR16 | in excess of 149 mph, 240 km/h |
| 205/45ZR17 88W | 168 mph, 270 km/h |
| 285/35ZR19 99Y | 186 mph, 300 km/h |
Most recently, when the Y-speed rating indicated in a service description is enclosed in parentheses, such as 285/35ZR19 (99Y), the top speed of the tire has been tested in excess of 186 mph, 300 km/h indicated by the service description as shown below:
| 285/35ZR19 99Y | 186 mph, 300 km/h |
| 285/35ZR19 (99Y) | in excess of 186 mph, 300 km/h |
As vehicles have increased their top speeds into Autobahn-only ranges, the tire speed ratings have evolved to better identify the tires capability, allowing drivers to match the speed of their tires with the top speed of their vehicle.
======================================================
Determining the Age of a Tire
When it comes to determining the age of a tire, it is easy to identify when a tire was manufactured by reading its Tire Identification Number (often referred to as the tire’s serial number). Unlike vehicle identification numbers (VINs) and the serial numbers used on many other consumer goods (which identify one specific item), Tire Identification Numbers are really batch codes that identify the week and year the tire was produced.
The U.S. Department of Transportation (DOT) National Highway Traffic Safety Administration (NHTSA) requires that Tire Identification Numbers be a combination of the letters DOT, followed by ten, eleven or twelve letters and/or numbers that identify the manufacturing location, tire size and manufacturer's code, along with the week and year the tire was manufactured.
Tires Manufactured Since 2000
Since 2000, the week and year the tire was produced has been provided by the last four digits of the Tire Identification Number with the 2 digits being used to identify the week immediately preceding the 2 digits used to identify the year.
Example of a tire manufactured since 2000 with the current Tire Identification Number format:
[TABLE="width: 95%"]
[TR]
[TD]DOT U2LL LMLR 5107[/TD]
[TD][/TD]
[/TR]
[TR]
[TD] 51[/TD]
[TD]Manufactured during the 51[SUP]st [/SUP]week of the year[/TD]
[/TR]
[TR]
[TD]07[/TD]
[TD]Manufactured during 2007[/TD]
[/TR]
[/TABLE]
While the entire Tire Identification Number is required to be branded onto one sidewall of every tire, current regulations also require that DOT and the first digits of the Tire Identification Number must also be branded onto the opposite sidewall. Therefore, it is possible to see a Tire Identification Number that appears incomplete and requires looking at the tire’s other sidewall to find the entire Tire Identification Number
The use of a partial Tire Identification Number on the one sidewall (shown above) reduces the risk of injury to the mold technician that would have to install the weekly date code on the top sidewall portion of a hot tire mold.
Tires Manufactured Before 2000
The Tire Identification Number for tires produced prior to 2000 was based on the assumption that tires would not be in service for ten years. While they were required to provided the same information as today’s tires, the week and year the tire was produced was contained in the last three digits. The 2 digits used to identify the week a tire was manufactured immediately preceded a single digit used to identify the year.
Example of a tire manufactured before 2000 with the earlier Tire Identification Number format:
[TABLE="width: 95%"]
[TR]
[TD]DOT EJ8J DFM 408[/TD]
[TD][/TD]
[/TR]
[TR]
[TD] 40[/TD]
[TD]Manufactured during the 40[SUP]th[/SUP] week of the year[/TD]
[/TR]
[TR]
[TD]8[/TD]
[TD]Manufactured during the 8[SUP]th[/SUP] year of the decade[/TD]
[/TR]
[/TABLE]
While the previous Tire Identification Number format identified that a tire was built in the 8th year of a decade, there was no universal identifier that confirmed which decade (tires produced in the 1990s may have a small triangle following the Tire Identification Number to identify the decade).
And finally, hold on to your sales receipt. Most tire manufacturer's warranties cover their tires for four years from the date of purchase or five years from the week the tires were manufactured. So if you purchase new tires that were manufactured exactly two years ago they will be covered for a total of six years (four years from the date of purchase) as long as you have your receipt. If you lose your receipt, your tires' warranty coverage will end five years from the week the tire was produced (resulting in the tire manufacturer's warranty coverage ending only three years from the date of purchase in this example).
Last edited:
:roflblack:
