Williams Team Principal, James Vowles, has identified the issue that caused "huge tyre degradation" for the team at the Belgian Grand Prix.
Both Alex Albon and Logan Sargeant were the only two drivers that pitted three times during the race, with the former dropping out of the top ten down to P14 towards the end.
Albon initially attributed to the team's poor tyre management to their aero package, but Vowles has another explanation for their sharp drop off during the race.
"What caused the degradation issue wasn’t anything that we would have learned in any of the practice sessions, it’s actually a problem that happened in the race,” he said.
“At the end of the race when we took all the wheels off, you have carbon surrounds which different teams call different things - they can be called ‘cake tins’ or ‘nozzles’ - but really they’re trying to control the flow of the very hot brake disc temperature into the tyre.
"What you want is really to get rid of all that warm air and push out the back of the car.
“But our cake tins were broken, probably during a pit stop, but it’s very difficult to pinpoint exactly where.”
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Williams convinced problem exacerbated tyre degradation
Vowles is confident this was the main reason why they suffered such a huge loss in lap time and ended up pitting for a third time.
“I’m fairly convinced that’s part of the reason why we suddenly had very significant degradation and why the beginning of the race looked almost so different to the end of the race and why we had to go to a three-stop.
“These changes are huge in terms of what it does, not just aerodynamically – clearly, we do a lot of work to make sure the air is going where we want it to go – but also in terms of temperature control of the rear tyres."
Albon remarked that the rain which hit the circuit helped cool down his tyres midway through the race, something the team also spotted on the data.
Vowles added: “It looked like the first stint was okay. The second stint was just about okay. And then we started to get into trouble. And then when the rain came, which cooled everything down, suddenly the car came alive again.
"When you work back from it, actually what happened was we were hampered by that [issue] on both cars and it’s quite significant as a contribution to why we suddenly went backwards.”