Tyre Size code
Tyres are sized numerically, the size is normally shown in the form “195/65R15 88H”. You can find this size on the side wall of your existing tyre, or in the vehicles handbook or tyre placard.
The first number, in this case “195”, is the width of the tyre at it’s widest point, in millimeters.
The next number, shown here as “65”, is the ratio of the tyres sidewall height to the width of the tyre, shown as a percentage. In this case the sidewall height would be 65% of the width.
The “R” stands for radial, if there is no letter then it is a cross ply tyre.
The third number after the R, in this example “15”, is the diameter of the wheel the tyre is designed to fit, in inches (yes, tyre sizes are a combination of metric and imperial units!)
Tyre load ratings
The next part, “88H”, denotes the load and speed ratings. The number is the load rating and the letter is the speed rating.
Standard load table (extract from ETRTO standards manual – 2010 page G7 – ref 42 psi (290 kPa))[11]
| Code | Weight | Code | Weight | Code | Weight | Code | Weight | |||
|---|---|---|---|---|---|---|---|---|---|---|
| 60 | 250 kg (550 lb) | 80 | 450 kg (990 lb) | 100 | 800 kg (1,800 lb) | 120 | 1,400 kg (3,100 lb) | |||
| 61 | 257 kg (567 lb) | 81 | 462 kg (1,019 lb) | 101 | 825 kg (1,819 lb) | 121 | 1,450 kg (3,200 lb) | |||
| 62 | 265 kg (584 lb) | 82 | 475 kg (1,047 lb) | 102 | 850 kg (1,870 lb) | 122 | 1,500 kg (3,300 lb) | |||
| 63 | 272 kg (600 lb) | 83 | 487 kg (1,074 lb) | 103 | 875 kg (1,929 lb) | 123 | 1,550 kg (3,420 lb) | |||
| 64 | 280 kg (620 lb) | 84 | 500 kg (1,100 lb) | 104 | 900 kg (2,000 lb) | 124 | 1,600 kg (3,500 lb) | |||
| 65 | 290 kg (640 lb) | 85 | 515 kg (1,135 lb) | 105 | 925 kg (2,039 lb) | 125 | 1,650 kg (3,640 lb) | |||
| 66 | 300 kg (660 lb) | 86 | 530 kg (1,170 lb) | 106 | 950 kg (2,090 lb) | |||||
| 67 | 307 kg (677 lb) | 87 | 545 kg (1,202 lb) | 107 | 975 kg (2,150 lb) | |||||
| 68 | 315 kg (694 lb) | 88 | 560 kg (1,230 lb) | 108 | 1,000 kg (2,200 lb) | |||||
| 69 | 325 kg (717 lb) | 89 | 580 kg (1,280 lb) | 109 | 1,030 kg (2,270 lb) | |||||
| 70 | 335 kg (739 lb) | 90 | 600 kg (1,300 lb) | 110 | 1,060 kg (2,340 lb) | |||||
| 71 | 345 kg (761 lb) | 91 | 615 kg (1,356 lb) | 111 | 1,090 kg (2,400 lb) | |||||
| 72 | 355 kg (783 lb) | 92 | 630 kg (1,390 lb) | 112 | 1,120 kg (2,470 lb) | |||||
| 73 | 365 kg (805 lb) | 93 | 650 kg (1,430 lb) | 113 | 1,150 kg (2,540 lb) | |||||
| 74 | 375 kg (827 lb) | 94 | 670 kg (1,480 lb) | 114 | 1,180 kg (2,600 lb) | |||||
| 75 | 387 kg (853 lb) | 95 | 690 kg (1,520 lb) | 115 | 1,215 kg (2,679 lb) | |||||
| 76 | 400 kg (880 lb) | 96 | 710 kg (1,570 lb) | 116 | 1,250 kg (2,760 lb) | |||||
| 77 | 412 kg (908 lb) | 97 | 730 kg (1,610 lb) | 117 | 1,285 kg (2,833 lb) | |||||
| 78 | 425 kg (937 lb) | 98 | 750 kg (1,650 lb) | 118 | 1,320 kg (2,910 lb) | |||||
| 79 | 437 kg (963 lb) | 99 | 775 kg (1,709 lb) | 119 | 1,360 kg (3,000 lb) |
Tyre Speed rating
The speed symbol is made up of a single letter “H” in our example or an A with one number. It indicates the maximum speed at which the tyre can carry a load corresponding to its Load Index.
| Code | mph | km/h | Code | mph | km/h | |
|---|---|---|---|---|---|---|
| A1 | 3 | 5 | L | 75 | 120 | |
| A2 | 6 | 10 | M | 81 | 130 | |
| A3 | 9 | 15 | N | 87 | 140 | |
| A4 | 12 | 20 | P | 94 | 150 | |
| A5 | 16 | 25 | Q | 100 | 160 | |
| A6 | 19 | 30 | R | 106 | 170 | |
| A7 | 22 | 35 | S | 112 | 180 | |
| A8 | 25 | 40 | T | 118 | 190 | |
| B | 31 | 50 | U | 124 | 200 | |
| C | 37 | 60 | H | 130 | 210 | |
| D | 40 | 65 | V | 149 | 240 | |
| E | 43 | 70 | Z | over 149 | over 240 | |
| F | 50 | 80 | W | 168 | 270 | |
| G | 56 | 90 | (W) | over 168 | over 270 | |
| J | 62 | 100 | Y | 186 | 300 | |
| K | 68 | 110 | (Y) | over 186 | over 300 |