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TIRES 101: SPECIFICATIONS

The Letters and Numbers on the Sidewall of your Tire

 
The Sidewall of your tire is labelled with several specifications that are important for you to understand.
Here is a brief explanation on some of the most common specifications.

A. SECTION WIDTH:
Section width is the width of an inflated tire in inches at its widest point.
 

B. ASPECT RATIO:
Section width and height are used to determine the Aspect Ratio. The lower the ratio, the shorter the sidewall.
 

C. RADIAL:
The "R" stands for "radial"construction.
 

D. RIM SIZE:
The diameter of the wheel (not the tire) in inches.
 

E. LOAD INDEX:
The load index number corresponds to the maximum load-carrying capacity of the tire. Refer to load index values in the chart to the right.
 

F. SPEED RATING
The speed rating corresponds to the tire's maximum speed capability (under optimal conditions).
 

G. LOAD:
This value refers to the type of load amount a tire is designed to handle. XL stands for Extra Load. The absence of a letter value automatically indicates Standard Load which may or may not be represented by the letters SL.
 

H. M+S
If shown, M+S stands for "Mud and Snow" indicating that the tire has been designed to perform in these conditions. Note: All winter tires must bear the 3 Peak Mountain Snowflake (3PMS) symbol indicating suitability for winter application.



UTQG Ratings:
UTQG stands for Uniform Tire Quality Grading. This ratings consist of the following 3 components: Traction, Temperature and Treadwear.
 

Speed Rating  Speed Category:
Symbol: MPH km/h
M 51 130
N 87 140
P 93 150
Q 99 160
R 106 170
S 112 180
T 118 190
U 124 200
X 130 210
V 149 240
W 168 270
Y 186 300
XR 149 240
(Y) 186 300
Load
Index
Wt.
lbs.
75 853
76 882
77 908
78 937
79 963
80 992
81 1019
82 1047
83 1074
84 1102
85 1135
86 1168
87 1201
88 1235
89 1279
90 1323
91 1356
92 1389
93 1433
94 1477
95 1521
96 1565
97 1609
98 1653
99 1709
100 1764
Load
Index
Wt.
lbs.
101 1819
102 1874
103 1929
104 1984
105 2039
106 2094
107 2149
108 2205
109 2271
110 2337
111 2403
112 2469
113 2535
114 2601
115 2679
116 2756
117 2833
118 2910
119 2998
120 3086
121 3197
122 3307
123 3417
124 3527
125 3638
126 3748
Load
Index
Wt.
lbs.
127 3858
128 3968
129 4079
130 4189
131 4299
132 4409
133 4541
134 4674
135 4806
136 4938
137 5071
138 5203
139 5357
140 5512
141 5677
142 5842
143 6008
144 6173
145 6393
146 6514
147 6779
148 6944
149 7165
150 7387
151
152

TRACTION


Traction grades range from AA, A, B and C (AA being the highest grade). These letters represent a tire's ability to stop on wet pavement as measure on a specified government test course. Any tire rated below C is considered unacceptable for road use.

TEMPERATURE


The temperature grades range from A, B and C (A being the highest and C the lowest). These letters denote a tire's ability to dissipate heat under a controlled indoor test environment. A tire rated below C is considered not approved for road use.

TREADWEAR


This is the wear rate of the tire, comparable only to other tires within a tire manufacturer's line. 100 is the baseline. A tire with a rating of 200 will last twice as long on the government's course as compared to a tire rating 100.