10 Tyre Myths Busted – Dunlop facts behind the most common assumptions

Tyre with pick-up

Pick-up removed to show clean tyre with depth indicators

Weaving to keep/get warm tyres – Dunlop designs tyres to optimise how to build and retain heat. After extensive testing Dunlop has found that the most efficient way to manage this is by braking and acceleration in a straight line rather than weaving which can over-stress the compound, take it past its peak slip angle and have a negative impact of consistency.
Lower pressures means faster – it’s actually a trade-off – lowering pressures increases the size of the area where the tyre is in contact with the track (contact patch) whereas higher pressures provide more support and can give more confidence. This needs to be considered in different ways for different tracks. At Le Mans, where you have very high speeds and large braking zones, especially in line, then a higher pressure gives more support and can give higher performance especially with high downforce cars. When you run at tight and twisty tracks you may want to run lower rear pressures to increase traction and lateral grip. The Dunlop track support team works with each of the partners to optimise for each track.
Soft compounds do not always mean faster lap times. At Dunlop we prefer to talk more about compound stiffness rather than soft or hard, because depending on the type of compound and temperature, the stiffness of the tyre can be the determining factor on performance and not the ‘softness’ of the compound. Different constructions could mean that the harder compound tyre is actually quicker. It also depends on how the tyre works with a particular set-up and chassis. In 2015, KCMG won the LMP2 class using just nine sets of the hardest compound tyres for the full race. The car set the second fastest LMP2 laptime of the race, with two drivers being in the top-five fastest lap times.
The tyres look terrible! [insert picture]Tyres looking like this look badly worn but actually as cars travel on the track small amounts of compound are worn off the tyre and laid onto the track. Over time these rubber deposits ‘marbles’ build up into small balls that get squashed onto the tyres and a driver travels over them. This is particularly noticeable in endurance racing where this is a lot of overtaking with drivers needing to go off the ‘clean’ racing line. When you see a tyre-technician ‘scraping’ the tyres – he’s actually removing the pick-up so that they can be used for another stint later in the race.
Colder temperatures means needing softer compounds – it all depends on driving styles & driver preference but also the chassis, track and set-up. 2015 saw all three options on the track at the same time.
The fastest laps are set when the tyres are new – Dunlop designs tyres for endurance, so the goal is to have as much consistency as possible throughout the time that the tyres are on the car. In 2014, Le Mans winner Jota Sport’s Oliver Turvey set the team’s fastest lap times in a fourth stint on tyres that had been racing for approaching three hours.
Tyres are black rubber – our tyres are actually only around one-third rubber. The black colour comes from the carbon black which provides much of the strength in the compound - and that forms around another third of the ingredients. The remaining third of the tyre is made up of materials such as steel, nylon, aramid, Kevlar, hybrid materials plus our secret ingredients in our confidential products.
Tyres are produced by machine – our road tyres are automated but each of the 2000 Dunlop tyres being raced at Le Mans has been built by hand.
Tyres are fitted before the start of the race – Teams only have a limited number of wheel rims and weather conditions can change so we frequently have to refit tyres throughout the race. During the 24 hour race last year, 1800 tyres were fitted at an average rate of 1.25 minutes per tyre – that’s just 5 minutes to strip and refit a set of tyres continually for 24 hours.
Le Mans is a 24 Hours race – It may be a 24 hour race for the cars, but to fit the tyres from first thing in the morning, through the race and then strip the used tyres at the end of the race is closer to a 36 hour day. The fitting takes place in shifts but the race support engineers are with their assigned teams from start to finish.