TYRES 101

ALL ABOUT TYRES

HOW TO READ A TYRE’S MARKINGS
Sidewall markings of a tyre contain the following:

  • Section Width
  • Aspect Ratio
  • Structure
  • Rim Diameter
  • Load Index
  • Speed Index
For example, a tyre marked
235/85 R 16 120/116S means:

235 : Nominal tyre section width (mm)
85 : Tyre aspect ratio (%)ratio of the sidewall height to the section width
R : Structure Radial construction
16 : Nominal rim diameter in inches
120/116 : Load index indicates the maximum load capacity(1400 kg in this case)
S : Speed index indicates the maximum authorised speed(180 km/h in this case)

 

WHAT IS A SPEED INDEX?TOP

The speed index indicates the maximum speed at witch the tyre can carry the load corresponding to its load index

Speed Index Maximum Speed(km/h) Maximum Speed(mph)


L
120 km/h 75 mph


N
130 km/h 81 mph


P
150 km/h 93 mph


Q
160 km/h 99 mph


R
170 km/h 106 mph


S
180 km/h 112 mph


T
190 km/h 118 mph


H
210 km/h 131 mph


V
240 km/h 149 mph


W
270 km/h 168 mph


Y
300 km/h 186 mph


ZR
>240 km/h 149 mph


ZR(Y)
>300 km/h 186 mph

Note: for speed index V, W and Y (whether or not marked ZR), load capacity restrictions apply above 210km/h for V, above 240km/h for W, and above 270km/h for Y. Contact us for further information.

WHAT IS A LOAD INDEX?TOP

The load index is a numerical code associated with the maximum load a tyre can carry under specific service conditions

Load Index Maximum load per tyre(kg) Load Index Maximum load per tyre(kg)
62 265 kg 95 690 kg
63 272 kg 96 710 kg
64 280 kg 97 730 kg
65 290 kg 98 750 kg
66 300 kg 99 775 kg
67 307 kg 100 800 kg
68 315 kg 101 825 kg
69 325 kg 102 850 kg
70 335 kg 103 875 kg
71 345 kg 104 900 kg
72 355 kg 105 925 kg
73 365 kg 106 950 kg
74 375 kg 107 975 kg
75 387 kg 108 1000 kg
76 400 kg 109 1030 kg
77 412 kg 110 1060 kg
78 425 kg 111 1090 kg
79 437 kg 112 1120 kg
80 450 kg 113 1150 kg
81 462 kg 114 1180 kg
82 475 kg 115 1215 kg
83 487 kg 116 1250 kg
84 500 kg 117 1285 kg
85 515 kg 118 1320 kg
86 530 kg 119 1360 kg
87 545 kg 120 1400 kg
88 560 kg 121 1450 kg
89 580 kg 122 1500 kg
90 600 kg 123 1550 kg
91 615 kg 124 1600 kg
92 630 kg 125 1650 kg
93 650 kg 126 1700 kg
94 670 kg 127 1750 kg

Note: Extra Load (or XL) indicates a tyre that has a higher load rating than would normally apply to its size. Reinforced (or Reinf.) indicates a tyre that has a higher load rating than would normally apply to its size.

TYRE SELECTION AND FITMENTTOP

Tyre selection and fitment

When fitting replacement tyres, ensure that they are the same size, load index and speed symbol as recommended by the vehicle manufacturer. For any other fitment (for example a tyre conversion), seek the advice of a tyre specialist.

For best performance, tyres should be used in identical sets of four (unless the vehicle is specified with different front and rear tyre sizes).

When tyres are not fitted in complete sets of four, we advise that tyres are not mixed across an axle.

When fitting a pair of tyres, we recommend that the new tyres are fitted to the rear axle for reasons of additional stability on slippery surfaces.

4-Wheel-Drive vehicles

We strongly recommend that tyres are used in identical sets of four on 4 wheel drive vehicles (same make, pattern, load index/speed symbol). The vehicle manufacturer’s recommendations should also be followed.

SAFETY RECOMMENDATIONSTOP

Your tyres are the only point of contact between your vehicle and the road. You must therefore ensure that the quality and performance of your tyres are maintained.

To do so, we recommend that you comply with the following safety advice and instructions for use. This advice from the Michelin Group is valid unless there are more restrictive local regulations: legal, regulatory requirements, etc.

Fitting and dismounting

Fitting, dismounting, inflating and balancing tyres must be performed with appropriate equipment and assigned to qualified personnel, and who will ensure in particular :

  • Compliance with legislation and manufacturer’s regulations in the choice of tyres: structure, size, speed symbol, load capacity rating, Passenger Car or Light Truck categories.
  • Verification of the external and internal appearance of the tyre by the installer prior to fitting.
  • Compliance with procedures for fitting, dismounting, balancing and inflating the tyre, and the systematic replacement of the valve.
  • Taking account of the fitting instructions on the tyre sidewalls (rotation direction or fitting direction).
  • Compliance with the pressure during use recommended by the vehicle manufacturer, the tyre manufacturer or the expert fitter.
  • Taking account of the characteristics of specific tyres (low profile, run-flat, self-sealing tyres, etc.).
  • After fitting the wheel to the vehicle, it is important to use a suitable torque wrench to achieve the optimal torque defined by the vehicle manufacturer.
Handling and storage

Tyres must be stored :

  • In a ventilated, dry and temperate area, out of direct sunlight and bad weather.
  • Away from any chemicals, solvents or hydrocarbons capable of altering the nature of the rubber.
  • Away from any object capable of penetrating the rubber (sharp metal, wood, etc.).

Do not store in stacks for long periods unless the tyres are mounted and inflated. Avoid crushing the tyres under objects.

Keep away from naked flames or any incandescent objects, any substance capable of causing sparks or electrical discharges (battery chargers, etc.).

The use of protective gloves is recommended for handling tyres.

Use of the tyre

Tyres should be selected in compliance with the original equipment of the vehicle, as defined by its manufacturer or by an official organization. Any other configuration must be approved by a tyre professional, who can propose the solution best suited to the vehicle and its use, whilst still complying with existing legislation.

A second-hand tyre must be checked by a tyre professional before use. On the same axle, it is strongly advised to use two tyres with the same tread pattern design. When replacing two tyres, it is recommended that the new tyres or the less worn tyres be fitted on the rear axle.

When fitting a vehicle with winter tyres, it is recommended that all four tyres are winter tyres, especially if they are studded. Do not use tyres at an unsuitable pressure, or at a speed or load higher than their rating.

A temporary spare wheel must not be used permanently.

Monitoring and maintenance

Check tyre pressure (including the spare wheel) monthly. Correct tyre pressure if it no longer corresponds to that recommended by the vehicle manufacturer. Tyre pressure should be checked when cold (when the vehicle has been stationary for at least 2 hours or having travelled for less than 3km at low speed) or, if hot, add 0.3 kpa to the recommended pressure.

Inflation with nitrogen still requires tyre pressure to be checked frequently. In the event of unusual pressure loss, have the internal and external condition of the tire checked, as well as the condition of the wheel and valve.

Check tyre wear (replacement is necessary when the legal wear level is reached), and consult a tyre professional in the event of abnormal wear or difference in wear between two tyres on the same axle. Any visible puncture, cut or deformation must be carefully examined by a tyre professional. Do not use a damaged tyre or one that has run flat without consulting a professional.

For tyres designed to run flat under certain conditions, you must comply with the operating instructions supplied by the tyre manufacturer.

Any abnormal occurrence such as vibration, noise, or pulling must be checked immediately personally and then by a tyre professional.

All repairs must be made by a tyre professional, using mushroom repairs only.

Any tyre showing clear signs of wear or ageing (“cracking”, etc.) must be examined by a tyre professional using mushroom repairs only, even if it is un-run or little used (example: spare wheel, tires fitted to caravans, motor homes or trailers).

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