A car may not brake to arrive at a space in order to slip stream. You are never obliged to slipstream, it in merely an option. One player rolls the dice and consults the weather table on the board. Players then secretly decide which tyres they will use. Separate weather rolls are made for trials and the race.
Conditions are wet during trials and races.
A car equipped with wet tyres adds one space to each move ending inside a corner. A car equipped with dry tyres adds three spaces to each move ending inside a corner. Conditions are normal during trials and races. A car equipped with either type of dry tyre follows their rules. A car equipped with wet tyres doubles tyre penalties in corners and swerving.