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.

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 tire's 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
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	1019	462
82	1047	475
83	1074	487
84	1102	500
85	1135	515
86	1168	530
87	1201	545
88	1235	560
89	1279	580
90	1323	600
91	1356	615
92	1389	630
93	1433	650
94	1477	670
95	1521	690
96	1565	710
97	1609	730
98	1653	750
99	1709	775
100	1764	800
101	1819	825
102	1874	850
103	1929	875
104	1984	900
105	2039	925
106	2094	950
107	2149	975
108	2205	1000
109	2271	1030
110	2337	1060