Which is why Michelin, developer of road and race tyres, would like more single-seaters to move to larger wheels. It even pitched for the F1 tyre contract from 2017, hoping to replace Pirelli, but a move to 18in rims was a condition of its application. (Pirelli subsequently inked a new deal with F1 through to 2019).
“For us to go to F1, we need a good reason to do so,” says Pascal Couasnon, director of Michelin Motorsport. If Michelin doesn’t learn anything for the road, it’s not interested. The trouble is, not many people in F1 have hitherto been interested in moving to a larger wheel and tyre.
Hence, Michelin has developed some 17in tyres and fitted them to a Formula Renault 2.0, and some 18s and fitted them to a Formula Renault 3.5 – a single-make formula from which some drivers have stepped straight to F1.
Michelin claims a lot of benefits – not just that it’ll develop better road tyres as a result. It thinks that 13s hold back suspension engineers and drivers, because the large, flexible sidewall blunts set-up adjustments made to a racing car. A 17in or 18in tyre, with smaller, probably stiffer sidewalls, makes a car far more sensitive to set-up changes. “It gives more opportunity to the team engineers to adjust the car’s setting, and make more [lap time] difference from box to box than before,” says Philippe Mussati, Michelin Motorsport’s customer competition department manager.
In closed formulae like Renault 2.0 and 3.5 (from which Renault, although not Michelin, is withdrawing next year), Mussati says, the only difference is the driver and the car’s set-up. “And on 17in or 18in, the setting is much more important than it used to be with 13in tyres,” he adds.
Bigger tyres are also meant to be cheaper for teams. A 17in or 18in wheel also gives space for bigger brakes, which means they can be made from cheaper, lower-tech materials yet still retain the same stopping power and degradation.
At the moment, Michelin has aimed to get the same wear and performance characteristics from the larger tyre as the smaller one. The result is that, at the moment, it’s a little heavier – around 0.5kg a corner – and has the same wear rate, but turns out to be up to a second faster a lap.
“We are probably 50% of the way there,” says Couasnon, who describes the tyre as a “first or second draft”. He says there’s still “optimisation of the compound and the structure of the tyres” to do, but “the profile itself is done”.
The lower profile – not truly low, which helps the appearance, by my reckoning – is said to make the car’s steering responses sharper than before. I have a go in both the 2.0 and 530bhp 3.5 cars but, well: I haven’t tried either on 13s, I don’t know the circuit or the car and I’m not a racing driver.