Speed ratings signify the safe top speed of a tire under perfect conditions. Common speed ratings are:
| Q=99 MPH, 160km/h |
V=149 MPH, 240km/h |
| S=112 MPH, 180km/h |
W=168 MPH, 270km/h |
| T=118 MPH, 190km/h |
Y=186 MPH, 300km/h |
| U=124 MPH, 200km/h |
Z=149 MPH, 240km/h and over |
| H=130 MPH, 210km/h |
|
Load Ratings
Many tires come with a service description added on the end of the tire size. These service descriptions contain a number, which is the load index, and a letter which indicates the speed rating. The load index represents the maximum load each tire is designed to support. Becase the maximum tire load capacity is branded on the tire's sidewall, the load index is used as a quick reference.
| 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 |
|
