Now, I’m not about to go around letting your tyres down at night, lads, but as I sat watching someone park one, and then somebody else try to slot a Range Rover into a parking space, I thought: you really have bought the wrong car for this location.

Tyred of complication

One of the legislative measures that tyres have to comply with are maximum levels of rolling resistance to maintain efficiency; you can’t make a tyre out of Blu Tack, no matter how grippy that might be.

Is it difficult, then, I asked a Pirelli tyre engineer last week, to marry that up with the demand for wider, low-profile tyres that offer big levels of grip? Not so much, he said: if anything, it’s more of an issue on narrower tyres with higher sidewalls, which fl ex more to provide extra comfort. Every bit of bounce in a sidewall is using energy that a stiffer set-up would use to keep rolling forwards.

So once you have stiff tyres and fit them onto a several-tonne vehicle, they’ll roll to their heart’s content. It’s the little, light, easily stopped cars with some squidge that are more problematic.

On a slightly related note, it’s increasingly common to find tyres fitted with foam inserts to reduce cabin noise. They’re pretty effective and can – although not necessarily by much – also reduce drive-by noise from outside, too. Now, foam is by definition very light but it does add weight where you wouldn’t want it, in unsprung mass: the bits between the suspension and the road. The lighter those are, generally the better, because the suspension doesn’t have to work so hard to control light things as it does heavy ones.

Tyres are noisier if they’re big and fat and wide, and foam makes them a little bit heavier again. Maybe we should have a bit less of them.


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