Find what the code after your tire size means. The number is the load index, the maximum weight one tire can carry at its maximum inflation pressure. The letter is the speed rating, the maximum sustained speed the tire is certified for. Type the code from your sidewall, for example 113T, or use the charts below.
Load index values follow the ISO load index table (kilograms per tire at the tire’s maximum inflation pressure; pounds converted). Speed symbols are the standard maximum sustained speeds. For an LT tire with two numbers such as 121/118, the first is single-wheel use and the second is dual-wheel use. A P-metric tire fitted to a light truck, SUV or van is normally derated by dividing its load capacity by 1.10. Always use at least the load index and speed rating on your vehicle’s door placard.
Tire speed rating chart
The speed symbol is the last letter of the service description, such as the T in 265/70R17 113T. It is tested under controlled laboratory conditions; it is not a recommendation to drive at that speed.
| Speed rating | Maximum speed (mph) | Maximum speed (km/h) |
|---|---|---|
| L | 75 mph | 120 km/h |
| M | 81 mph | 130 km/h |
| N | 87 mph | 140 km/h |
| P | 93 mph | 150 km/h |
| Q | 99 mph | 160 km/h |
| R | 106 mph | 170 km/h |
| S | 112 mph | 180 km/h |
| T | 118 mph | 190 km/h |
| U | 124 mph | 200 km/h |
| H | 130 mph | 210 km/h |
| V | 149 mph | 240 km/h |
| W | 168 mph | 270 km/h |
| Y | 186 mph | 300 km/h |
A tire marked ZR in the size, such as 245/40ZR18, is rated above 149 mph (240 km/h). Newer ZR tires also carry a regular symbol such as W or Y that gives the exact rating; a Y in parentheses, (Y), means above 186 mph.
Tire load index chart
The load index is the weight one tire can carry at its maximum inflation pressure, from the ISO load index table. Multiply by four for the set; the total must be at least the gross axle weights of your vehicle, which you can find on the door placard.
| Load index | lbs per tire | kg per tire |
|---|---|---|
| 60 | 551 | 250 |
| 61 | 567 | 257 |
| 62 | 584 | 265 |
| 63 | 600 | 272 |
| 64 | 617 | 280 |
| 65 | 639 | 290 |
| 66 | 661 | 300 |
| 67 | 677 | 307 |
| 68 | 694 | 315 |
| 69 | 717 | 325 |
| 70 | 739 | 335 |
| 71 | 761 | 345 |
| 72 | 783 | 355 |
| 73 | 805 | 365 |
| 74 | 827 | 375 |
| 75 | 853 | 387 |
| 76 | 882 | 400 |
| 77 | 908 | 412 |
| 78 | 937 | 425 |
| 79 | 963 | 437 |
| 80 | 992 | 450 |
| 81 | 1,019 | 462 |
| 82 | 1,047 | 475 |
| 83 | 1,074 | 487 |
| 84 | 1,102 | 500 |
| 85 | 1,135 | 515 |
| 86 | 1,168 | 530 |
| 87 | 1,202 | 545 |
| 88 | 1,235 | 560 |
| 89 | 1,279 | 580 |
| 90 | 1,323 | 600 |
| 91 | 1,356 | 615 |
| 92 | 1,389 | 630 |
| 93 | 1,433 | 650 |
| 94 | 1,477 | 670 |
| 95 | 1,521 | 690 |
| Load index | lbs per tire | kg per tire |
|---|---|---|
| 96 | 1,565 | 710 |
| 97 | 1,609 | 730 |
| 98 | 1,653 | 750 |
| 99 | 1,709 | 775 |
| 100 | 1,764 | 800 |
| 101 | 1,819 | 825 |
| 102 | 1,874 | 850 |
| 103 | 1,929 | 875 |
| 104 | 1,984 | 900 |
| 105 | 2,039 | 925 |
| 106 | 2,094 | 950 |
| 107 | 2,150 | 975 |
| 108 | 2,205 | 1,000 |
| 109 | 2,271 | 1,030 |
| 110 | 2,337 | 1,060 |
| 111 | 2,403 | 1,090 |
| 112 | 2,469 | 1,120 |
| 113 | 2,535 | 1,150 |
| 114 | 2,601 | 1,180 |
| 115 | 2,679 | 1,215 |
| 116 | 2,756 | 1,250 |
| 117 | 2,833 | 1,285 |
| 118 | 2,910 | 1,320 |
| 119 | 2,998 | 1,360 |
| 120 | 3,086 | 1,400 |
| 121 | 3,197 | 1,450 |
| 122 | 3,307 | 1,500 |
| 123 | 3,417 | 1,550 |
| 124 | 3,527 | 1,600 |
| 125 | 3,638 | 1,650 |
| 126 | 3,748 | 1,700 |
| 127 | 3,858 | 1,750 |
| 128 | 3,968 | 1,800 |
| 129 | 4,079 | 1,850 |
| 130 | 4,189 | 1,900 |
How to read the service description
- P265/70R17 113T: one load index (113, or 2,535 lbs per tire) and one speed rating (T, 118 mph).
- LT265/70R17 121/118S: a light truck tire with two load indexes. 121 (3,197 lbs) applies when the tire runs alone on the axle end; 118 (2,910 lbs) applies on dual rear wheels. S means 112 mph.
- Load range letters on LT tires (C, D, E, F) describe the construction and maximum inflation. Use the load index for the actual capacity.
Choosing replacement tires
- Match or exceed the load index and speed rating on your vehicle’s door placard. A lower load index can overload the tire.
- When a passenger (P-metric) tire is fitted to a light truck, SUV or van, its load capacity is normally reduced by dividing by 1.10, so it needs a higher load index to carry the same weight.
- A higher speed rating usually means a stiffer tire and can change ride comfort and tread life; it is not automatically better.
- Changing the tire size? Compare the dimensions with our tire size calculator.
Frequently asked questions
What does 113T mean on a tire?
113 is the load index: each tire can carry up to 1,150 kg (2,535 lbs) at its maximum inflation pressure. T is the speed rating: certified up to 118 mph (190 km/h).
Can I use a tire with a higher load index?
Yes. A higher load index than the placard requires is fine. A lower one is not, because the tire could be overloaded.
Can I use a lower speed rating than my original tires?
It is not recommended, and some vehicle makers and insurers require at least the original rating. The vehicle’s top speed and handling were set with the original rating in mind; winter tires are a common, clearly labeled exception.
Why does my LT tire have two load numbers?
The first number is the capacity when the tire is used alone at the end of an axle, and the second when it is paired with another tire on dual rear wheels.