Michelin’s racing department is experimenting with larger wheels and argues they have greater relevance to road car technology
Matt Prior
1 November 2015

The first surprise: a single-seater on 18in wheels doesn’t look rubbish. I’d feared it might, but no. This Formula Renault 3.5, 
on deeply dished 18in-diameter wheels, looks rather good to me.

Single-seat racing cars, up to and including Formula 1, have been using littler wheels – usually of 13in – for years. I don’t know why. There was a time when ultimate performance road tyres were around 13in in size, I suppose, but only if you drive a Caterham are they still.

Road cars left 13in wheels behind long ago, but single-seat racing cars – small, I suppose, and light – stuck with them. Which is fine, unless, say, you’re a tyre manufacturer and you think road tyres ought to benefit in some way from tyres you design for competition; technology transfer, breed improvement, that sort of thing.

It’s the sort of concept you might think hardly ever happens these days, given how far removed motorsport is from road driving, except for one thing: a tyre compound Michelin used at Le Mans just four years ago is used in its Pilot Sport Cup road tyre today.

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.

Racers in the series who’ve tried them, though, like them. Good drivers like anything that makes them faster and think they’ll be able to set a car up better than their competitors.

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Comments
9

1 November 2015
Low profile may be better for racing cars, but in the 'real world' of road cars, there are kerbs and pot holes etc....

1 November 2015
Greenracer wrote:

Low profile may be better for racing cars, but in the 'real world' of road cars, there are kerbs and pot holes etc....

I think you've completely missed the point of what is trying to be achieved here as low profile road tyres are already very common on road so Michelin aren't trying or going to rewrite the rule book as far as their usage is concerned. 18 inch is a very common size on sports cars now so if top line motorsport were to adopt and then develop the technologies at this more relevant size it could only be a good thing you would think?

1 November 2015
I don't buy in to the reason that the need for F1 to adopt bigger wheels is due to road car development. Larger wheels using lower profile tyres are already used in some other forms of motorsport like touring cars and sports car racing, while the performance and demands of the latter's P1 class cars are similar to F1 cars so the wheel and tyre development on that front already exists at the highest level. I personally think the demand to have larger wheels on F1 cars is is for aesthetic reasons only.

1 November 2015
Lanehogger wrote:

I don't buy in to the reason that the need for F1 to adopt bigger wheels is due to road car development. Larger wheels using lower profile tyres are already used in some other forms of motorsport like touring cars and sports car racing, while the performance and demands of the latter's P1 class cars are similar to F1 cars so the wheel and tyre development on that front already exists at the highest level. I personally think the demand to have larger wheels on F1 cars is is for aesthetic reasons only.

It also saves resources. The lower profile tires mean less material being used. Vulcanized rubber is basically a non recyclable material, at least for the time being. And F1 goes through a truck load of them every single race. De-vulcanizing exists but its poorly developed, expensive, and the resulting material isn't the same as the original rubber. Until someone figures out to completely undo the vulcanizing process tires are a HUGE drain on a non sustainable resource.

1 November 2015
It reads more like an advertorial than a genuine article. Also appears somewhat biased, given that there is no mention of any of the disadvantages of larger wheel sizes - greater unsprung weight, more gyro effect etc. Quite apart from which Michelin did not win the contract to supply F1 with tyres, so for the time being at least, the question of larger wheels is academic.

1 November 2015
They might look better on single seater's but would they be any faster, there may be benefits for car set up but would these be lost having to stay off the kerbs ?
Road cars have been using increasingly big rims for years but quite often it is not because of brake size issues but aesthetics as manufacturers try and disguise modern bulky car designs. There is no dynamic reason to fit 19" wheels to a Nissan Qashqai 130 dci.

1 November 2015
I have wondered for years why F1 wheels are so small and have huge high profile tyres. Surely bigger wheels and low profile tyres would work much better? Saying that, the coolest ever F1 cars from the 70's and 80's had amazing comedy gumballs that look absolutely terrific.

1 November 2015
I have wondered for years why F1 wheels are so small and have huge high profile tyres. Surely bigger wheels and low profile tyres would work much better? Saying that, the coolest ever F1 cars from the 70's and 80's had amazing comedy gumballs that look absolutely terrific.

1 November 2015
Why not an unique tyre for wet and dry as in Formula E.

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