Spa 24 hours: the biggest adventure in GT racing

There's something almost mystical about Spa-Francorchamps. Ask any driver and you'll get a decent idea of just how special the 7.004-kilometre circuit situated in the middle of the vast Ardennes Forest feels to drive. And, for one weekend a year, the Belgian track becomes the centre of the world for Pirelli.

Pirelli will bring over 13,000 tyres to Spa-Francorchamps this weekend, as it is the exclusive supplier for not only the GT World Challenge field – with a capacity entry of 65 cars – but also for all the support categories taking part.

These include the one-make Lamborghini Super Trofeo Europe championship, the SRO Motorsport organised GT2 European Series and GT4 European Series, as well as the single seater categories: Formula Regional European and FFSA French Formula 4.

It is a mammoth logistical task to transport all these tyres to and from the circuit, so it's little surprise that the Spa 24 Hours is Pirelli's biggest, busiest and most important race of the entire season. More than 100 people from Pirelli are required to service the needs of all the teams, with a dedicated facility close to the paddock that's like a mini tyre factory, working day and night. It even has its own restaurant.

What makes the wheels go round is quite literally the tyres. Replacing the outgoing DHE compound, the DHF tyre is a completely redesigned product that will equip all the categories this year, populated by the world's most prestigious car manufacturers from Aston Martin to Porsche. But it's not just about the tyres themselves. How you use them as part of a round-the-clock strategy is just as important. Sometimes, you get little choice, as rain is a very common feature. Microclimates are characteristic of the Ardennes region and the race two years ago was red-flagged for nearly seven hours on Sunday morning, due to a torrential downpour during the night. Such is the length and topography of the track that conditions can vary wildly from one part of the circuit to the other. It's important to have a solid strategy at Spa, but it's equally important for that strategy to be extremely adaptable. As well as weather, Full Course Yellows can disrupt the action on a regular basis. These are a very good opportunity to make a pit stop while losing less time than in normal circumstances. But you can't always plan it. As one experienced team principal put it: “You need to find that delicate balance between luck and judgement…”

Unless it's raining, you can't just use all the tyres you like and hope for the best. Teams are allowed a maximum of 30 sets of dry tyres, which must be used from free practice onwards. Two sets from the official test day can be carried over as part of the 30-set allocation, while an additional new set is allowed just for the top 10 cars in qualifying (which have to be used in the Super Pole session). There are no limitations on wet weather tyres though. While Spa-Francorchamps is a long track, traffic can become an additional challenge. It's easy to see why. A total of 23 Pro entries will take part, with Porsche and Mercedes fielding the highest number of cars across the various classes, with 13. Audi is represented by 12 cars while Lamborghini – which has never won the Spa 24 Hours, despite coming close – will enter nine cars, with five from BMW and Ferrari also taking to the grid. McLaren will have four cars, Aston Martin three, while Bentley fields a solitary Continental GT3.

Ferrari won last year's thrilling race following a sensational overtake from Alessandro Pier Guidi, as heavy rain hit the race in the last hour.

After a private test on Tuesday 26 July and the return of the traditional parade from the circuit to the town of Spa the next day, the competitive action kicks off for real with free practice on Thursday 28 July. Practice begins at 10:50, with pre-qualifying taking place at 16:15. Then it's onto qualifying, in the traditional Q1-Q4 format, starting at 20:40 before night practice begins at 22:20. Super Pole for the fastest 20 cars from qualifying will take place on Friday 29 July at 19:01, while the race itself begins on Saturday at 16:45.

What happens after that is impossible to say…