Ever thought why a formula one car needs change of tyres during a race whereas for a road car, the tyres are changed only after about 30,000*km?
WHY? Tyres play a major role in a car’s performance in terms of stability, aerodynamics & obviously traction. Tyres are the only contact between the car & the road. At high speed grip is very important. The tyre composition of a f1 car and road car is different because tyres in F1 are designed for maximum grip and to last for at most 200 km and – like everything else on a the car – is constructed to be as light and strong as possible. The most distinguishing factor between the formula one tyres & that of a road car is that the former work (provide grip) at a temperature between 90 to 110 deg celcius (you can see that the tyres are covered with heating blankets before the race). The speed, acceleration and braking, load & lateral forces handled by F1 tyres are very very large than that of a road car and hence they wear out after certain amount of usage and subsequently start loosing grip for which they need to be replaces.
What? Over the race weekend, each driver has access to 11 sets of dry-weather tyres (six of the harder ‘prime’ specification and five of the softer ‘option’ specification), four sets of intermediate tyres and three sets of wet tyres.
One of the above tyre type is selected depending on track condition, whether dry, moist or wet.
How? To know anout how these tyres are changed please check previous post – https://world2talkabout.wordpress.com/2012/11/26/tyre-change-in-just-3-5-seconds/
* for majority hatch backs in India.
Calculation for 68 spare tyres: As per F1 regulation each driver has access to 11 sets (slick) + 4 sets (intermediate) + 3 sets (full wet) = 11×4+4×4+3×4 = 72. Out of these 4 tyres are can be considered as running. Hence spare tyres = 72 -4 = 68.
Additional Information: One set of ‘prime’ tyres must be returned to the tyre supplier before Practice Two, and one set of each specification before the start of Practice Three. This leaves a driver with eight sets of dry-weather tyres (four of each specification) for the rest of the event, but one set of each spec must be returned to the tyre supplier before the start of Saturday’s qualifying session. At the start of the race the cars that took part in Q3 must be fitted with the tyres the driver used to set his grid time. Unless wet tyres have been used, drivers must use both dry tyre compounds during a race and failure to do so will see them excluded from the results.