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Reading Your Tire Sidewall - Understanding Tire Hieroglyphics
Understanding Tire Hieroglyphics
There is a lot to learn from the sidewall of your tire. Although at first glance you may think you stumbled across tire hieroglyphics, you've actually found molded into the tires side its own user manual.
Tire Size
Example P205/55R16 91W
(There are 25.4 millimeters per 1 inch.)
Load Index and Speed Rating
The load index tells you how much weight the tire can support when properly inflated. Load indicesSymbol Speed range from 74 - 150 for passenger tires with each numeric value corresponding to a certain carrying capacity. The carrying capacity for each value can be found on a load index chart. On each U.S. passenger car tire, the load limit is listed in pounds. European tires have the load limit listed in kilograms and sometimes pounds.
Speed Symbol
Speed (km/h)
Speed (mph)
A1
5
3
A2
10
6
A3
15
9
A4
20
12
A5
25
16
A6
30
19
A7
35
22
A8
40
B
50
31
C
60
37
D
65
E
70
43
F
80
G
90
56
J
100
62
K
110
68
L
120
75
M
130
81
N
140
87
P
150
94
Q
160
R
170
106
S
180
112
T
190
118
U
200
124
H
210
V
240
149
W
270
168
Y
300
186
(Y)
Above 300
Above 186
DOT Serial Number
The "DOT" symbol certifies the tire manufacturer's compliance with the U.S. Department of Transportation tire safety standards.
Below is a description of the serial number. Starting with the year 2000, four numbers are used for the Date of Manufacture, first two numbers identify the week and the last two numbers identify the year of manufacture.
Prior to year 2000 three numbers are used for the Date of manufacture, first two numbers identify the week and the last number identifies the year of manufacture. To identify tires manufactured in the 90's a decade symbol (a triangle on its side) is located at the end of the DOT serial number.
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