Homologation and tyre lists
There are two nominated tyre companies authorised to supply tyres to competitors in the 2013 FIA World Rally Championship: Michelin and DMACK.
There are two lists of homologated tyres. List one covers all cars except world rally cars and each tyre company must register with the FIA one gravel tyre, one asphalt, one winter asphalt tyre and one studded snow tyre for the 2013 season.
World rally cars must use tyres from list two only. Again, tyre manufacturers must register one gravel tyre, one asphalt tyre, one winter tyre and one studded snow tyre for the 2013 season. It is possible for list one and list two to be identical. List one tyres must be commercially available but list two tyres may not be.
Tyres for gravel events
For gravel events, the gravel tyre will be available in two different compounds, usually a hard and soft compound, but will still have the same tread pattern and tyre construction. No extra grooves are allowed to be hand cut into the tyre.
Tyres for asphalt events
On asphalt events, two different compounds will be available but both will again have the same pattern and construction. However, for Rallye Monte Carlo only, competitors will be offered an additional 'extra soft' compound but will still only have a total of two compounds available for use on the event.
Asphalt tyres must be E-marked, have two radial grooves and at least 21% of the surface area must be made up from grooves. At all times during an event, the tread depth of asphalt tyres must not be less than 1.6mm across at least three quarters of the tread pattern. A winter asphalt snow tyre is also available for use on Rallye Monte Carlo and can be used in studded or non-studded form.
Tyres for snow events
On Rally Sweden, the only snow event of the season, competitors must use a tyre which fits on a 7 x 15 inch wheel, the same size as a normal gravel wheel.
Each tyre company can register one replacement asphalt and one replacement gravel specification tyre once each season. This is commonly referred to as the joker tyre and the new specification will replace the original specification which cannot be used thereafter.
For each event, a tyre manufacturer must choose one compound in advance which will be its nominated compound for the rally. When specified by the event regulations, 16 tyres of the other compound may be used instead of the nominated compound. However, the same maximum number of tyres is allowed on the event.