Pirelli is anticipating a two-stop strategy will be used by most drivers at the Belgian Grand Prix as the Ultrasoft tyre is used for the first time at Spa.

The decision to bring the softest compound in the range is a result of the successful use of the Supersoft tyre at the famous circuit last year and with the 2017 rubber one step harder than it was a season ago in effect the same compounds are being used again.

High degradation of that Ultrasoft compound is still expected, however, through Spa's long high-speed corners but the Italian supplier is interested to see how it operates after running at Francorchamps just a few weeks ago.

"Pirelli was racing at Spa for the 24 Hours last month, which showcased everything this circuit is famous for changeable weather, unpredictable competition, and heavy demands on the tyres," their F1 boss Mario Isola said.

"Now that we are bringing the Ultrasoft tyre there for Formula 1, we would expect those demands to increase further with the latest generation of cars.

"Two stops would appear to be a likely strategy but we will know more after the first free practice sessions," he added.

"Working out the optimal race strategy is especially tricky at Spa as it has to be flexible: the possibility of rain, safety cars, or even a red flag – as we saw last year – means that teams often have to react to changing circumstances rather than follow a fixed plan."

As for the allocation of tyres between teams, Red Bull and McLaren have gone the most aggressive with nine sets of Ultrasoft. Local favourite Stoffel Vandoorne has joined another Spa hero Max Verstappen and Daniel Ricciardo with three sets of Supersoft and a single Soft, while Fernando Alonso has two sets of each.

The top two teams a fairly similar with seven sets of Ultrasoft for Ferrari and six for Mercedes. The two Scuderia drivers and Lewis Hamilton have three sets of Supersoft while Valtteri Bottas has four but the Finn re-aligns with Sebastian Vettel and Kimi Raikkonen with three sets of Soft.

Toro Rosso are also among the more aggressive teams with eight sets of Ultrasoft's, while Williams has the most Supersoft's of anyone splitting their allocation 7-5-1.

With quite a variety of strategies up and down the grid, it will be interesting to see just who gets it right, that's of course if the sun shines long enough at Spa to find out. 

The full allocation for all teams can be seen below: