Daniel Ricciardo wants Formula One teams to be given an extra set of extreme wet weather tyres in 2018 to prompt more running during rain-affected practice sessions.
Only five drivers set times in a session that saw limited wet-weather running when second practice got underway with 45 minutes on the clock, following a heavy downpour between FP1 and FP2 in Japan. Fourteen drivers ventured out on track, but the majority limited their running to either single or multiple installation laps.
Under F1's current regulations, teams are permitted just three sets of Pirelli's extreme wet tyres for grands prix weekends. Ricciardo believes making another set available on Friday would promote more running when rain does hit.
"Next year ... they [currently] give us an extra set of inters for Fridays but not extremes, so that is why we didn't run because if we need to use the extreme we want to save it for when it counts in qualifying," the Australian said. "It was good some guys ran, but to get all of us running they need to give us a set of extremes for Friday."
After Red Bull claimed an unexpected win at last weekend's Malaysian Grand Prix, Mercedes is expected to return to form around the power-hungry Suzuka circuit. But with further rain on the radar for Saturday, Ricciardo reckons uncertain conditions could play into Red Bull's hands.
"It seems like the rain is going to stay overnight -- at least P3 looks wet. Qually at this stage is hard to say, but it looks like it will be wet. We need to save our cards for tomorrow. We have probably more to gain.
"Ferrari and Mercedes, everyone expects them, and they always expect to be at the front. Where we can be there at times, so any kind of uncertainty or changing of conditions gives us a bit more gamble to take."
Ricciardo, who ended a dry first session third-fastest and just over 0.3s off pacesetter Sebastian Vettel, hopes his team will also be competitive if it remains dry.
"[FP1 was pretty good. We went out really early because we thought the rain was going to come. We just got into the program and in the end we were pretty good. Ferrari were quite strong, and Mercedes always get better on a Saturday. So we still have some pace to find but it was a pretty good morning. The car felt good. We just need to find some global lap time now, but the balance was pretty good."