In rainy conditions all drivers are obliged to use the wet when running behind the safety car ahead of a race start.
However, the anomaly is that once conditions become raceable the wet tyre is regarded as being of little use.
In the Spa sprint, there was a rush into the pits for intermediates once the race got underway, with half the grid coming in at the start, and the remainder at the end of the first flying lap.
“The extreme tyre is pretty pointless tyre, it's really, really bad,” said Russell. “It's probably six, seven seconds a lap slower than the intermediate. And the only reason you'd ever run the extreme wet is because you'd aquaplane on an intermediate. So that needs to be substantially improved.
“The aquaplaning with fairly little water is really substantial. I remember watching the old onboard videos of 2007 with [Felipe] Massa and [Robert] Kubica in Fuji, so much water, they were still pushing flat out.
“I remember doing test days here in F3 and Formula Renault, on Michelin and Hankook, aquaplaning wasn't really a thing, but I appreciate we're doing well over 200 miles an hour. It's not straightforward. But yeah, there needs to be some significant improvements."
Ferrari’s Charles Leclerc, who starts Sunday’s Belgian GP from pole position, agreed with Russell.
“There's some work that needs to be done there because we've got extreme tyres that are really slow but that are really good for aquaplaning,” he said. “But we never drive in those conditions because of visibility.
“So then whenever it's drivable we all we need to go on intermediates. So yeah, it's quite tricky at the moment. I think the extreme should be faster and closer to the inters, so we run more on the extreme than the inters, basically.”
Earlier in the Spa weekend, Russell suggested that the FIA would have to make “bold decisions” about racing in wet conditions, and the GPDA director said he was happy that the sprint started after a delay for heavy rain followed by several laps behind the safety car.
"I think they did a good job under the circumstances,” he said. “It's very challenging. Still, incredibly dangerous conditions, you are doing 300 kilometres an hour on the straight, and you can't see 50 metres in front of you.
“It seems particularly bad in this circuit. I don't know if it's the humidity, or the trees or what, but the spray just doesn't seem to disperse. And it's like you're driving into a cloud.”
He also suggested that the safety car laps should be replaced by the cars running at speed – but not racing – in order to help disperse the water.
“I felt like those four laps under the safety car didn't really give us a lot,” he said. “It was the same I think in Japan, we were doing lots of laps under the safety car and it didn't really improve things.
“So maybe a solution for the future is if they allow us to do two, three, four laps at full racing speed and then bring the safety car out to neutralise the pack, and go again, because after two laps of racing things were much better.”
