Skinny tires OK, but isn't 155 on 19" a bit exotic?

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In this blog: Do electric vehicles need such narrow tires and do they look good?

Skinnies fit Renault Twizy, though it looks cooler in ELIA mods. You know Germans, they not only put wider tires, but also wider custom fenders. Some other Germans did the opposite, however, despite they are far from popular in doing this – BMW i3's tires are super skinny for its width. Not that we haven't seen skinny tires, but 155/70 on 19"?!?...

That's the size of i3's front tires, produced by Bridgestone. And we may find this huge rim - skinny tire combo a bit odd, but it's the key thing here.

The reason that i3 has such tires is that they provide significantly lower drag and friction, without compromising traction. Well, this is something everybody would want to test we guess, as it sounds kind of difficult to believe in.gumi bridgestone BS EP500 BMW i3

Facts are more important than belief, however – it's a technology which we're sure was put to test a lot before it came to market. Here the advantages:

Generally lower diameter tires are more susceptible to "deformation" in motion. Bigger diameter and tire wall on the other hand significantly reduce deformation, which saves a lot of energy, otherwise lost in the internal friction. Add to this the narrow thread, which reduces drag and you have the BMW's decision explained.

Your first thought about a low friction narrow tire would probably be – "Fine, but what about the traction?" We'll leave this to BMW engineers – doubt they decided on such compound if it would not pefrorm well in traction.

THE SIZE

BMW i3 hit the market in mid November 2013 with the following four Ecopia EP500 ologic (plus two winter) tires sizes:

  • 155/70 R19 84Q;
  • 175/60 R19 86Q;
  • 155/60 R20 80Q;
  • 175/55 R20 85Q;
  • BLIZZAK LM-500 ologic winter
  • BLIZZAK NV ologic с Multicell Northern countries compound.

To the low drag and specific compound for the ologic tech we can only add that pressure in the tires is higher. And, on the "green" side, BMW's goal is achieve 50% CO2 reduction by 2050 with these tires.

So it looks like we'll have to get used to these wheels as they will be introduced in more and more cars in the coming years. Even on such ships like BMW 7-Series (couple of years ago some weird 7-Series images in skinny tires surfaced the net). It's about efficiency of course, but we're sure the performance maniacs would stick to wider tires (not everyone cares about the green).

As for the exotics – with the small range in its first version, i3 definitely benefits from having 155/70/19 tires to extend the range. So it may look exotic, but there's a reason for these tires.

[Lead image: BMW Group Bulgaria]

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