Reading a Tyre Sidewall

Tyre Information : How to read a sidewall

Every tyre sidewall shows information about the manufacturer, size, model etc. Here's a summary of the most important information and what it means.

Example: 205 40 R17 84W

• 205 - means the tyre has a nominal section width of 205 millimetres.
• 40 - is referred to as the aspect ratio and is the height of the tyre sidewall as a percentage of the nominal section width.
• R - means the tyre has a radial construction, the most commonly used of three different types of tyre construction: cross ply, radial and bias belted.
• 17 - means it fits a 17" diameter wheel.
• 84 - is the load index. This identifies the maximum load capacity of a tyre when driven at maximum speed. Overloading a tyre, by carrying more weight than it is designed to or running at a lower than specified pressure can cause heat build up and blow outs. Load indexes for passenger cars usually range from 70 - 110 and the maximum load per individual tyre is shown in the table below.

• W - is the speed rating. This represents the maximum speed that a tyre can sustain at full load. The example shown is rated for speeds up to 168mph.
• Other common speed ratings are:
  Q - for cars with max speeds up to 100mph (160km/h)
  R - for cars with max speeds up to 105mph (170km/h)
  S - for cars with max speeds up to 113mph (180km/h)
  T - for cars with max speeds up to 118mph (190km/h)
  H - for cars with max speeds up to 130mph (210km/h)
  V - for cars with max speeds up to 150mph (240km/h)
  Z - for cars with speeds over 150mph (240km/h)
  W - for cars with max speeds up to 168mph (270km/h)
  Y - for cars with max speeds up to 186mph (300km/h)

You should always replace a car tyre with the same or a higher speed rating and we recommend that you check against the speed rating approved by the vehicle manufacturer.