Have you ever wondered what all those numbers and letters stamped on the tyre sidewall mean? Find out how to easily decipher them: tyre sizes, speed rating, load index and other markings will no longer hold any secrets for you!

By Published On: 31 May 2021Categories: General tyre information945 words5.3 min read
Copyright © rezulteo

How to read your tyre size?

Here are 3 ways to find approved tyre sizes for your vehicle:

Tyre size

The brand, model and size of a tyre are always indicated on its sidewall. Take the example of this winter tyre, the Bridgestone Blizzak, on which you can see the following marking: 205 55 R 16 91 T Here’s the breakdown:

205 tyre width in millimetres
55 ratio between the sidewall height and the tyre width as a %
R tyre structure (most tyres available have R for radial)
16 rim diameter in inches
91 load index
T speed rating
© rezulteo

Load index

The Load Index indicates the maximum weight a tyre can carry at its maximum speed. In the following table, you will find the maximum weight per tyre in kilograms for each load index.

Tyre load index Maximum load in kg Tyre load index Maximum load in kg
75 387 101 825
76 400 102 850
77 412 103 875
78 425 104 900
79 437 105 925
80 450 106 950
81 462 107 975
82 475 108 1000
83 487 109 1030
84 500 110 1060
85 515 111 1090
86 530 112 1120
87 545 113 1150
88 560 114 1180
89 580 115 1215
90 600 116 1250
91 615 117 1285
92 630 118 1320
93 650 119 1360
94 670 120 1400
95 690 121 1450
96 710 122 1500
97 730 123 1550
98 750 124 1600
99 775 125 1650
100 800 126 1700

Speed rating

The Speed Rating indicates the maximum speed the tyre is capable of reaching. The following table shows the maximum speed in miles per hour and kilometres per hour for each speed rating.

Tyre speed rating Maximum speed in mph Maximum speed in km/h
Q 99 160
R 106 170
S 112 180
T 118 190
U 124 200
H 130 210
V 149 240
ZR >149 >240
W 168 270
Y 186 300

You can also refer to the following load index and speed rating tables

Technical markings

On the tyre’s sidewall, you can also find some technical information. For example on winter tyres you will usually see the M+S marking (Mud and Snow) which is mandatory for snow tyres in some countries. You might also see the 3PMSF marking (3 Peak Mountain Snow Flake) represented by a snowflake inside 3 mountain peaks. This label provides a guarantee of high winter performance.

Markings can also be found on some high performance tyres specially developed for top of the range models from car manufacturers such as Porsche or Mercedes. In this case, a marking on the sidewall indicates the manufacturer’s approval or ‘homologation’.

Some technical markings apply to all tyre brands, others are manufacturer specific.

M + S Mud + Snow marking, specific to winter, 4×4 and all season tyres, indicating good grip performance on soft ground (snow, mud)
3PMSF   Symbol stamped on tyres that are specially designed for driving in snow and difficult winter conditions, it comprises a snow flake and a three peak mountain (“Three Peak Mountain Snow Flake”) 
RF or Reinforced(XL, Extraload or Reinforced)   Tyre with a higher load index, suitable for heavy vehicles such as people carriers, estate cars, large saloons or vans.
TL or Tubeless Tyre with an inner liner integrated inside the tyre, which therefore does not require an air chamber.
TT or Tube Type   Tyre requiring the use of an air chamber
TWI   Tread Wear Indicator
MO   Mercedes fitment
N0/N1/N2…   Porsche fitment
M3   BMW M3
R01   Audi
* BMW Approval
J   Jaguar
G1   Original equipment on certain vehicles (C6, Laguna 2, Espace 4…)
B   Bentley or Audi
C1   Chrysler Viper
F or K1   Ferrari
S8   Lexus RX300
AMS   Aston Martin
OWL   Outline White Letter
ULW   Ultra light weight tyre construction
MFS   Max Flange Shield
RBL   Recessed Black Letter
WLT   White Letter
RWL   Raised white lettering
FR   Flange rim protection
ML   Sidewall flange protection
FP   Rim protection
WW   White wall
RB   Black lettering
RW   White lettering

Markings common to all tyre brands

Some manufacturer specific markings

RFT Runflat tyre
RW Runflat tyre for Mercedes
SSR Self-Supporting Runflat tyre
Vmax Tyre designed for ultra-high performance saloon cars
ContiSeal Technique that prevents air escaping from the tyre by means of a sealant layer that provides a seal around the object that caused the puncture.
ContiSilent Technology that uses polyurethane foam to reduce the effects of tyre noise
FL Front left tyre
FR Front right tyre
Runonflat Runflat tyre
Noise Shield Technology using polyurethane foam to reduce interior vehicle noise 
EMT or ROF Runflat tyre
SoundComfort Technology using polyurethane foam to reduce interior vehicle noise
Zp Zero pressure runflat tyre
Green X Green tyre offering a high level of energy efficiency in terms of fuel consumption, wear and wet grip.
Run flat Runflat tyre
Allroad Audi allroad
Seal Inside Tyre structure that allows you to drive without losing air pressure even after a puncture.

Regulation markings: DOT, UTQG…

Finally, in some countries specific markings are required by law.

In Europe, passenger car tyres are subject to a noise regulation. An approval number stamped on the tyre (e.g: E2 02-03 527) certifies compliance with this regulation.

The United States requires the following two markings:

The DOT code (Department of Transportation)

The DOT code means that the tyre complies with the safety standards set by the American Department of Transportation. In particular, it indicates where the tyre was produced and its date of manufacture.

UTQG (Uniform Tire Quality Grading) marking

When buying tyres, the UTQG marking aims to help consumers assess the performance of various models on the basis of 3 criteria:

  • Treadwear: Tread wear grade (score between 60 and 620)
  • Traction: Traction grade on wet roads (grade from A to C, where A is the highest grade and C the minimum acceptable)
  • Temperature : Temperature grade (grade from A to C, where C is the legal minimum)

UTQG ratings are based on each manufacturer’s own assessment. Therefore they do not allow tyres from different brands to be compared with each other. If you want to assess the performance of a tyre, it is best to refer to the tyre label and our rezulteo ratings, which are based on test results conducted by tyre industry experts.

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