Tyre Construction
• Tread: Part of the tire
that contact the road
surface
• Bead: Part of the tire
that contacts the rim on
the wheel
• Plies: layers of
relatively inextensible
cords embedded in the
rubber (Bias & Radial)
ISO Tyre Code
• Tyre Type
• Tyre Width
• Aspect Ratio
• Construction
• Wheel Diameter
• Load Index
• Speed Rating
ISO Tyre Code
P185/70R13 82H
• Tyre type
•
•
•
•
P : Passenger car tyre
LT : Light truck tyre
ST: Special Trailer
T: Temporary (restricted for "Space-Saver" spare wheels)
• Tyre width (unit: mm)
• Widest section of the tyre
• Aspect Ratio:
• Tyre width divided / tyre thickness * 100%
• Construction
• B: Bias ply
• R: Radial ply
• Wheel diameter (unit: inch)
• Diameter measured from bead seat to bead seat
Tyre Code Calculation
185/70R13 82H
• Rim diameter is 330.2 (13 inches )
• Thickness is 185 x 70% = 129.5
• Outside diameter is 129.5 x 2 + 330.2 = 789.9
• Load Rating is 82 = 475kg
• Speed Rating is H = 210km/h (Max.)
Load Rating
Index
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
Load
(kg)
315
325
335
345
355
365
375
387
400
412
425
437
450
462
475
487
Load
(lbs)
694
717
739
761
783
805
827
853
882
908
937
963
992
1019
1047
1074
Load
Index
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
Load
(kg)
500
515
530
545
560
580
600
615
630
650
670
690
710
730
750
775
Load
(lbs)
1102
1135
1168
1201
1235
1279
1323
1356
1389
1433
1477
1521
1565
1609
1653
1709
Load
Index
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
Load
(kg)
800
825
850
875
900
925
950
975
1000
1030
1060
1090
1120
1150
1180
1215
Load
(lbs)
1764
1819
1874
1929
1934
2039
2094
2149
2205
2271
2337
2403
2469
2535
2601
2679
Speed Rating Symbol
Speed Symbol
S
T
U
H
V
W
Y
Speed Category
Performance Rating
112 mph (180 km/h)
118 mph (190 km/h)
124 mph (200 km/h)
130 mph (210 km/h)
149 mph (240 km/h)
168 mph (270 km/h)
186 mph (300/h)
Z
Above 149 mph (240 km/h)