Lewis Hamilton and Nico Rosberg have chosen only four sets each of Pirelli's SuperSoft compound, which is the fewest of any team, while Red Bull will have six sets of the softest compound at its disposal.
In contrast, Ferrari have selected seven sets of the SuperSoft rubber, despite its limited durability according to Pirelli's Paul Hembery.
"You can’t imagine many laps coming from a supersoft at Spa, that's for sure," Hembery told F1i.
"It’s going to have limitations so that’s going to be interesting to see how they all play out with that. The race tyre is likely to be the soft, possibly the medium, the medium tyre has worked very well there in the past.
"But that’s the point of having the three compounds, they can take a particular direction that they feel suits their car, their performance and the strategy that they’re trying to follow. We’ll see how it pans out."
Asked whether Mercedes choice was more in line with what Pirelli expected, Hembery agreed.
"Yes, you’d say yes, but then everyone has got their own idea and concept of what they want to do this year and I think that’s good.
" It’s good, so we’re happy for them to go down that route and try something a bit different."