To C5, or not to C5? That is the question for F1 Canadian GP qualifying

With the softest grade of tyres available for the Canadian Grand Prix, many of Formula 1's drivers and teams are once again unsure which of the compounds are the best option for qualifying in Montreal.

Following the introduction of the C6 compound for 2025, and Pirelli's decision to be more aggressive with its selection of tyres for races, the softest rubber should - on paper, at least - offer more performance over a single lap.

However, the delta between it and the C5 are very small; with higher temperatures expected on Saturday, it would not be inconceivable that the C6s struggle to hold up for a full lap without overheating - thus, it may well be prudent to save a set of mediums for qualifying.

This was a situation seen at both the Imola and Monaco races, which also had use of the three softest compounds; in Q3 at Imola, Fernando Alonso claimed fifth on the grid with a lap on the mediums.

This prompted a few more teams to explore the medium compound at Monaco; although only Alex Albon did his best Q3 lap on the yellow-walled tyre, this had been half a second down on his effort in Q2.

George Russell had mused that "clearly a number of teams are thinking about this medium tyre as well", indicating that Mercedes may opt to hang onto a new set on Saturday.

Most teams chose to stick to the soft tyres in FP1, with very few drivers opting to explore the mediums or hards in that session. As such, Pirelli noted that nine of the 10 teams have saved two sets of hards - Sauber being the only team to burn up a set in FP2 - to use in the race. Sauber, however, feels that an extra set of C5s may well offer dividends on Sunday.

Gabriel Bortoleto, Sauber

Photo by: Glenn Dunbar / Motorsport Images

Carlos Sainz predicted that "there's probably going to be a bit of a mess again with the tyres", owing to the small time difference (approximately around a tenth) between the two compounds.

Although this would usually mean that using the medium would give away performance, this again relates to how the drivers manage the softs; if the C6s are put under too much load in the opening sector, they may struggle to deliver the optimal level traction out of the hairpin and final chicane - both crucial parts of the circuit which are particularly power-sensitive.

"Personally, I don't know and it looks like nobody knows," Pierre Gasly reckoned. "I'm sure it's going to be a question - I think ultimately on our side, we're probably more trying to just try to get the car in the best place we can.

"Of course, this will be part of it and if there is a tiny bit to get from [using a medium], we'll try to take it. We'll go through everything tonight."

Alonso, who benefitted from Aston Martin's decision to employ the mediums in Imola qualifying, explained that he needed to see more in Saturday's final practice session given that the Silverstone squad did not use the C5 in FP2.

Aston's practice session was hampered by Lance Stroll's early FP2 shunt, limiting its data available, although Alonso found that he was struggling with graining on the softs. He noted that getting the tyres into the window had also been a challenge.

"They seem to take a [few] laps to get into temperature, but then when they are in temperature, they grain," the veteran Spaniard noted. "So, there is only one or two laps where you can be at performance.I think it's going to be the same tomorrow.

Fernando Alonso, Aston Martin Racing

Photo by: James Sutton / Motorsport Images

"We don't know [if mediums will work for qualifying]. Obviously, FP1, FP2 are the least important sessions of the weekend. We know the track is getting grippier throughout the weekend. It's a street circuit, so a lot of track evolution. We want to do a proper test tomorrow in FP3."

Pirelli chief engineer Simone Berra revealed in his post-session notes that graining had indeed been a wider problem, albeit with a chance for improvement as the circuit grips up with further running on Saturday.

He added that a two-stop race was likely for Sunday's 70-lap affair, stating that both medium and hard tyres were hanging on well during a race stint - which may yet vindicate Sauber's decision to keep a set of C5s back.

"The level of graining was quite high today, but the situation should improve, even if it is hard to say if this phenomenon will disappear completely in the race," said Berra.

"It will be interesting to see how the teams will tackle qualifying, both in terms of using the medium and managing the softs, as there is still a free practice session tomorrow. Simulations indicate that a two-stop is the quickest strategy and for the moment, there is no indication that this could change, but we will know more tomorrow afternoon."

Watch: He's Back! Will it be a strong return for Lance Stroll at the F1 Canadian Grand Prix?