Range, grip and silence: Why EV owners have to care about the tyres they use

Like a lot of owners of internal combustion engine cars, tyres were not something that I ever thought a lot about. Not being a car nut, and not looking for the ultimate in traction, performance and brand, tyres were things that I had to buy when the tread wore down.

When the platypus bill on a 20 cent coin became visible, it was time to change. And I’d basically go with whatever the people at the local tyre shop had in stock, or would recommend. Price was important, but it was vaguely comforting to go with a brand whose name you recognise. Yes, advertising does work.

My previous car was a Peugeot 207 wagon. It was a joy to drive but it was a diesel and often it sounded like a tractor. I doubt if I ever heard the tyres.

That’s all changed driving electric cars. The first thing you notice is the silence, and then you realise you can actually hear the road noise, the sound of tyres rolling over the asphalt, even the wind blowing past the mirrors, or the roof racks and the surfboard on top if you have them. You can really appreciate the quality of the sound system.

You get to appreciate smooth road surfaces, and rough surfaces become  an aural imposition, and so when it comes round to changing the tyres, suddenly that’s a big thing.

What sort of tyres does an EV need.  Which ones last the longest with the extra weight of the battery, which ones were best to support the sudden acceleration that I was now enjoying, along with the re-gen. Most of all, I wanted to know which ones were the quietist – because now I can hear them.

There are actually a few things to think about when you buy a tyre for an electric car. The noise, or lack of them, is clearly important, but so are things like rolling resistance (it adds to the range), its ability to support the extra weight of the battery, and its level of grip to deal with the instant torque (without dragging back the tyres on the surface).

So tyre choice has just become more complex, and a little more expensive. And it’s not just for EVs. Tyre manufacturers have had to work harder on their tyre development with the arrival of hybrids, which can deliver lengthy periods of driving with the combustion engine off.

My Model 3 arrived in 2019 with Michelin Pilot Sports in place, which came with “acoustic technology” – a layer of foam that helps deaden the sound. There are other options out there but – largely because of what the local tyre dealer has in stock and easily available on order – I went with Pilot Sports for the first few changes.

Michelin, however, offered the opportunity to try out the new Primacy 5 product, so I took the option when it came to the most recent change over at 133,000 kms.

And the improvement was instantly noticeable –  quiet, even quieter than the Pilot 4s they replaced before, great handling, and it soon became clear that they even boosted my range by nearly 10 per cent. Some four months and 10,000s down the track, that is still the case.

That’s the rolling resistance at work. Michelin reckons that the Primacy 5 delivers 13 per cent better mileage than other premium products.

And how to they do this? It turns out it is all about the “voids”, which are evenly distributed across the tread pattern to “limit repetitive noise and reduce noise sources coming from the air rushing into its grooves at the same time.” Intermediate ribs are designed to further reduce vibration and noise..

Michelin do most of their testing at Le Mans, where noise has never really been considered a problem and is probably a virtue, but where downforce and the need to save fuel are paramount, and where Michelin is trying out new materials with an eye on unsustainability and reducing its emissions.

EVs and hybrids are already more than 35% of the new car market in Australia, and far higher in Europe, where it is difficult to find a country that is not already at 50 per cent electrified.

In Norway, the market share of full battery EVs is already at 98.5 per cent. If you visit Oslo, you can appreciate the quietness, and the lack of pollution. Imagine how good it will be when the last of the diesel and petrol vehicles are cycled out.

Has the arrival of hybrids and EVs completely changed tyre development? “I wouldn’t say completely, but it’s certainly accelerated some areas, probably in noise and dealing with instant torque and the rim size evolution as well, because EVs usually have a pretty high rim size, says David, the marketing manager for Oceania at Michelin.

“So if you’ve got good rolling resistance, the tyres must still be able to have strong levels of grip but not be dragged back by the road surface. Safety is number one, but to balance resistance and grip is an exercise in compromise.

“What’s super interesting about Le Mans is that you have teams that are running extremely high performance cars. They’re hybrid, very high torque, very high down force – the tyres need to last as long as possible to save fuel and at different temperatures along the track.

“So what a tire goes through in Le Mans is quite remarkable, and now you build that tyre to exceed or match the performance with sustainable materials.”

Of course, how long tyres last always come down to the car and the driver, and the noise levels might ultimately be decided by the quality of the car build. In general terms, EVs will wear out tyres around 20 per cent quicker than those with conventional engines, because they are generally heavier, and because of the torque and the re-gen which also puts more strain on the tyre.

Michelin says the Primacy 5, which were introduced into the Australian market earlier this year, improves rolling resistance by around 5 per cent, has a shorter braking distance – 8% when new and 13% when worn – and improved longevity by around 20 per cent.