Reading the Sidewall of a Tire

Tire Class – “P”
The first character(s) in a tire size designate the tire’s class. In this example, “P” indicates that the tire is a passenger car tire. An “LT” before the tire size designates a light truck tire, and no letter before the size indicates that it is a European metric tire.
Section Width – “205”  

A metric tire’s section width is measured in millimeters. This measurement is taken from sidewall to sidewall. In this example, the section width of the tire is 205mm.

Aspect Ratio – “65”

This number refers to the height of the sidewall. It is a percentage of the section width. In this example, 65 percent of the section width of 205mm equals 133.25.

Tire Construction – “R”

The “R” in this example indicates radial tire construction.

Wheel Diameter – “16”
This indicates the wheel diameter in inches.

Tire Dimensions

Section Width

 The linear distance between th outside of the sidewalls of an inflated tire without any load on it (this does not include any sidewall decorations).

Aspect Ratio

This is also known as the Sectio Height. This is figured as a percentage of the section width. A tire size of 205/60R15 would have a section width of 205 millimeters and a section height of 60 percent of 205 millimeters.

Rim Width

The width between the flanges of the wheel (the part the bead of the tire touches).

Size (High Flotation)

Diameter – “35”

The first number indicates the tire’s diameter in inches. In this example, the tire manufacturer has determined that this is a 35″ tire. However, actual measured overall diameters vary from one manufacturer to the next.

Tire Width – “1250”

Standard tire width is indicated in inches with the decimal point removed. Therefore, in this example, the number 1250 indicates that this tire is 12.5″ wide.

Tire Construction – “R”
The “R” in this example indicates radial tire construction.
Wheel Diameter – “17”
This indicates the wheel diameter in inches.
Plies – “E”

This letter indicates the load carrying capacity of the tire in terms of its construction. A “C” indicates the tire has a 6-ply load carrying capacity. The tire is not actually built with 6 plies, but contains one or two plies of equivalent strength. A “D” is an 8-ply rating, and an “E” is a 10-ply rating. If there is no letter, the tire has a standard 4-ply rating.

Load Index & Speed Rating
Load Index – “92”
The load index indicates the maximum amount of weight a tire can safely carry. Load index ranges from 0 to 279 and corresponds with the load-carrying capacity of a tire. Passenger car tire load indices typically range from 75 to 105. It is very important to maintain the proper load index for your vehicle when replacing your tires. See our load index chart for more information.

Load Index

The load index refers to the load-carrying capacity of a tire, or how much weight a tire can support. For example, if a tire has a load index of 89, it can support 1,279 pounds (from below chart) at maximum air pressure.
Speed Rating – “H”
A tire receives its speed rating from the U.S. Government by meeting minimum standards for reaching and sustaining a specified speed. In general, a higher speed rating will result in better vehicle handling. See our speed rating page for more information and a list of the various speed ratings.
Load Index Load (lbs)
0 99
1 102
2 105
3 107
4 110
5 114
6 117
7 120
8 123
9 128
10 132
11 136
12 139
13 143
14 148
15 152
16 157
17 161
18 165
19 171
20 176
21 182
22 187
23 193
24 198
25 204
26 209
27 215
28 220
29 227
30 234
31 240
32 247
33 254
34 260
35 267
36 276
37 282
38 291
39 300
40 309
41 320
42 331
43 342
44 353
45 364
46 375
47 386
48 397
49 408
Load Index Load (lbs)
50 419
51 430
52 441
53 454
54 467
55 481
56 494
57 507
58 520
59 536
60 551
61 567
62 584
63 600
64 617
65 639
66 639
67 677
68 694
69 716
70 739
71 761
72 783
73 805
74 827
75 852
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
Load Index Load (lbs)
100 1764
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
127 3858
128 3968
129 4079
130 4189
131 4289
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 6614
147 6779
148 6844
149 7165
150 7385

Speed Ratings

A tire receives its speed rating by the U.S. Government through meeting minimum standards for reaching and sustaining a specified speed. What does that mean to you? Well, in general, a higher speed rating will result in better car handling.
Two important notes when considering speed rating:
  • We do not recommend downgrading the speed rating of your tires. This may result in poor handling and unpredictable steering. However, if you want better cornering response, there is no problem installing a higher speed rated tire on your vehicle.
  • Never mix and match tires with different speed ratings on your vehicle. This will cause serious problems with the handling of your vehicle.
    • Below is a list of speed ratings along with the corresponding speeds they represent. Remember, the speeds are test speeds, not recommended speeds.
    B – Up to 31 mph
    C – Up to 37 mph
    D – Up to 40 mph
    E – Up to 43 mph
    F – Up to 50 mph
    G – Up to 56 mph
    J – Up to 62 mph
    K – Up to 68 mph
    L – Up to 75 mph
    M – Up to 81 mph
    N – Up to 87 mph
    P – Up to 94 mph
    Q – Up to 100 mph
    R – Up to 106 mph
    S – Up to 112 mph
    T – Up to 118 mph
    U – Up to 124 mph
    H – Up to 130 mph
    V – Up to 149 mph
    W – Up to 168 mph
    Y – Up to 186 mph
    Z – 149 mph and over
    U.S. DOT & Safety Standard Markings

    DOT

    The “DOT” marking indicates that the tire meets or exceeds the U.S. Department of Transportation’s safety standard for tires.
    Manufacturer Plant Code – “CC”
    The first two letters following the DOT marking are codes to identify the manufacturer of the tire and the manufacturing plant.
    Tire Size – “9L”
    The third and fourth characters following the DOT marking are codes representing the tire size.

    Brand Characteristics – “YYY”

    The final three or four letters are codes representing other significant characteristics of the tire as determined by the manufacturer.
    Manufacture Week – “11”  
    The first pair of digits identifies the week the tire was manufactured. In this case, the tire was manufactured in the 11th week. The number 01 would indicate the first week of January, whereas the number 52 would indicate the last week of December.
    Manufacture Year – “05”
    The second pair of digits identifies the year that the tire was manufactured, in this case 2005.
    Treadwear, Traction & Temperature

    Treadwear – “520”

    The treadwear rating is a measurement of the tire’s durability, but not the projected tread life. It is important to remember that road surfaces, driving habits, and other factors determine actual tread life. Each tire manufacturer independently determines treadwear through their own tests. Treadwear is not based on any one industry or government standard.
    Traction – “A”
    The traction rating is a measurement of a tire’s ability to stop on a straight, wet surface under controlled conditions. It does not indicate the tire’s cornering ability on a wet surface or its traction on ice or snow. Traction grades include AA, A, B, and C, with AA being the highest grade available.
    Temperature – “A”
    The temperature rating is a measurement of a tire’s resistance to heat generation under normal operating conditions at recommended inflation pressures. Temperature grades range from A to C, with A being highest rated and therefore most resistant to heat generation.

    Treadwear, Traction and Temperature

    The US Government has established the UTQG, the Uniform Tire Quality Grading, to assist consumers in their purchase of tires. Basically it’s another tool to be used besides the opinions you gather from trusted friends, mechanics and whatever other sources you may have at your disposal. The key to using this system is to understand that it is a relative comparison system. The UTQG is not a safety rating and not a guarantee that a tire will last for a prescribed number of miles. Under UTQG, manufacturers use three criteria to grade tires: treadwear, traction and temperature. The information is right where you need it when buying the tire:
  • On the paper label affixed to the tread
  • On the tire molded into the sidewall

    • The treadwear grade is a comparative rating based on the wear of a tire when tested carefully under controlled conditions. For example the useful tread on a tire graded 400 should last twice as long as a tire graded 200. However, another tire manufacturer may grade a comparable design 300, so a grade of 150 would last just half as long under their grading scheme. The lesson learned is to not use one manufacturer’s grade versus the other, but instead to compare tire grades within a given brand. Actual treadwear performance can vary tremendously according to the tire’s real-world use. Variations in driving habits, service practices (most importantly air pressure maintenance), road conditions and climate affect tire life.

    Traction grades represent the tire’s ability to stop on wet pavement as measured under controlled conditions on asphalt and concrete test surfaces. As of 1997, the traction grades from highest to lowest are “AA”,”A”,”B” and “C”. A tire graded “AA” may have relatively better traction performance than a tire graded lower, based on straight-ahead braking tests. The grades do not take into consideration the cornering or turning performance of a tire.
    Temperature grades represent a tire’s resistance to heat and its ability to dissipate heat when tested under controlled laboratory test conditions. The grades from highest to lowest are “A”,”B” and “C”. The grade “C” corresponds to the minimum performance required by federal safety standard. Therefore, the “A” tire is the coolest running, and even though the “C” tire runs hotter it does not mean it is unsafe. The temperature grade is established for a tire that is properly inflated and not overloaded.
    Maximum Load Limit & Air Pressure

    Maximum Load Limit – “635 kg [1400 lbs]”

    This indicates the tire’s maximum load-carrying capabilities when the tire is inflated to its maximum inflation pressure, as indicated on the sidewall. Max load is based on standards set by the National Highway Traffic Safety Administration (NHTSA).
    Maximum Air Pressure – “300 kPa [44 psi]”
    This indicates the maximum operating inflation pressure of the tire. It does not indicate the manufacturer’s recommended inflation pressure, nor does it indicate the proper air pressure based on the vehicle the tire is mounted on. This category is also based on NHTSA standards.
    Note – Some tires are marked ‘Extra Load’, ‘XL’, or ‘RF’ (for reinforced). This simply denotes that the tire’s indicated maximum load and air pressure are higher than a standard load tire.
    Ply Construction
    This indicates what materials are used in the tire’s plies, and the quantity of each type included.

    Tire Construction

    To the casual observer all tires look the same. But if you look carefully, you’ll find modern tire construction offers a degree of handling, ride comfort, traction, treadwear and fuel economy that far exceeds tires built just a few years ago.
    Today there are tire designs that contain up to 200 raw materials as well as a complex architecture of steel belts, textile plies and computer designed tread patterns. Tire manufacturers strive to deliver the most competitive designs in terms of performance and wear.

    Rotation Direction

    Some tires indicate the direction of rotation on the sidewall, while others indicate a specific side of the tire that is intended to face outward from the vehicle. Another type of tire combines both indications. It is important that these tires be mounted according to the indicated instructions.
    Directional Tires
    Directional tires feature arrows on the sidewall that indicate what direction the tire should rotate when the vehicle is moving forward.
    Asymmetrical Tires
    Asymmetrical tires have the word “outside” labeled on the side of the tire that should face outward from the vehicle.
    Directional & Asymmetrical Tires

    Tires that are both directional and asymmetrical will indicate what direction the tire must rotate, as well as what side must face outward from the vehicle.