How to Read Tyre Markings and Sizes

Breakdown

Example of tyre size: 225/55 R 17 97 W

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225: corresponds to the tyre width in millimetres. In this example, the tyre is 225 mm wide.

55: indicates the tyre series, meaning the ratio between the sidewall height and the tyre width. In this example, the sidewall height is 55% of the tyre width. The lower the ratio, the lower the sidewall height.
Note: a lower sidewall height can improve cornering grip, but it also results in a firmer ride.

R: refers to the internal construction of the tyre. R indicates that the construction is radial. Almost all tyres in use today are of radial construction, meaning the textile cords in the casing run from one bead to the other.

17: indicates the inner diameter of the tyre, in other words, the rim height. This measurement is expressed in inches. In this example, the diameter is 17 inches.

97: is the load index of the tyre. This index shows the maximum load the tyre can carry when inflated to its maximum safe pressure. In this example, it does not mean the tyre supports 97 kg — the number 97 corresponds to a reference value found in a load index table. For an index of 97, the maximum load is 730 kg per tyre.

W: corresponds to the speed rating of the tyre and indicates the maximum speed at which the tyre can safely carry a load. Speed ratings range from A (lowest) to Y (highest), with one exception: H falls between U and V. As with the load index, each letter corresponds to a specific speed rating in km/h:

C: 60 km/h
D: 65 km/h
E: 70 km/h
F: 80 km/h
G: 90 km/h
J: 100 km/h
K: 110 km/h
L: 120 km/h
M: 130 km/h
N: 140 km/h
P: 150 km/h
Q: 160 km/h
R: 170 km/h
S: 180 km/h
T: 190 km/h
U: 200 km/h
H: 210 km/h
V: 240 km/h
W: 270 km/h
Y: 300 km/h
ZR(Y): over 300 km/h
ZR: over 240 km/h

Note: the tyre’s speed rating is an indicator of its capability — it does not authorise driving above legal speed limits.

Reference Table: Load Index vs Load per Tyre in kg

Load Index	Load per Tyre (kg)	Load Index	Load per Tyre (kg)	Load Index	Load per Tyre (kg)
70	335	87	545	104	900
71	345	88	560	105	925
72	355	89	580	106	950
73	365	90	600	107	975
74	375	91	615	108	1000
75	387	92	630	109	1030
76	400	93	650	110	1060
77	412	94	670	111	1090
78	425	95	690	112	1120
79	437	96	710	113	1150
80	450	97	730	114	1180
81	462	98	750	115	1215
82	475	99	775	116	1250
83	487	100	800	117	1285
84	500	101	825	118	1320
85	515	102	850	119	1360
86	530	103	875	120	1400

Other Markings

UTQG Code

The UTQG (Uniform Tire Quality Grading) standard is a North American regulation required by the U.S. Department of Transportation (FMVSS: Federal Motor Vehicle Safety Standards) for passenger car tyres.

Studded tyres (4x4 or off-road tyres), winter tyres, space-saver spare tyres, and tyres smaller than 12 inches are not covered by this standard.

This standard must appear on the sidewalls of tyres sold in the USA. Since almost all manufacturers operate in the American market, the UTQG marking is also found on the majority of tyres sold in Europe.

Manufacturing Information

These codes indicate when and where the tyre was manufactured. In this example:

DOT – Department of Transportation (USA)

BP – Code for the factory where the tyre was produced

M2 – Tyre size code

P711 – Optional code

4008 – Week and year of manufacture. In this case, week 40 of 2008.

Winter Markings

Two specific winter markings may be found on the sidewalls of tyres:

M+S

This marking indicates that the tyre is classified as a “winter” tyre in accordance with European regulations. However, its performance under winter conditions is not tested.

3PMSF

3 Peaks Mountain Snow Flake (3PMSF)
Tyres bearing this marking are designed for snowy road conditions and their performance is validated through testing.*

The three-peak mountain with snowflake symbol (3PMSF) on M+S (Mud & Snow) tyres identifies tyres intended for severe snow conditions.

*Winter braking performance test conducted according to ETRTO (European Tyre and Rim Technical Organisation) methods.

Warning: This “Safety Warning” marking is required in the USA.

SERIOUS DAMAGE MAY RESULT FROM:

- Tyre failure caused by under-inflation or overloading. Check the vehicle’s maintenance manual or the tyre placard (1).
- A blowout due to incorrect tyre/rim combination. Never exceed XX PSI (2) to seat the tyre beads on the rim. Only specially trained personnel should remove or fit tyres.
- Fitting radial and bias-ply tyres on the same vehicle, or fitting tyres of different sizes on the same axle.

(1) Tyre placard: required for vehicles in use in the USA, it describes the conditions of use for the tyres fitted to the vehicle.
(2) XX PSI (or YY kPa): manufacturer-specific value.