Bridgestone Announces Large Diameter Narrow Tires

[sheepdog 44]

Wow, i didn't realize BMW was using these much anticipated tires! For a visual comparison of the current mpg king RE92's: 165/65-R14 vs 155/70-R19 Tire Comparison - Tire Size Calculator

These have slightly better sidewall height, 4.27 vs 4.27 inches. 18.5% less revolutions per mile! 15 pound BMW I3 stock wheel vs 11 pound gen 1 Insight wheel.



Insight 165/65 r14 RE92 specs:
Stock Wheel
Mfg: Asahi Tec Corporation
Size: 14 x 5.5 J
Bolt Pattern: 4-100mm
Lug Size: 12 x 1.5mm
Offset: +45H
Weight: 11 lbs
Finish: Aluminum
Style: 12 slot

Stock Tire
Mfg: Bridgestone
Model: Potenza RE92
Size: 165/65 R14
Compound: 78S
Treadwear: 260
Traction: A
Temp: B
Weight: 11.5
Pressure: 44psi
RPM: 926

[freebeard]

bolt-patern.com won't let me select text so no link for them. But they say the i3's bolt pitch is 5x120mm. And the linked article lists 4 sizes:

Ecopia EP500 ologic tire is available in four sizes:

BMW i3 – Notice How Skinny Those Tires Are?
155/70 R19 84Q
175/60 R19 86Q
155/60 R20 80Q
175/55 R20 85Q

Snow tires (studded or studless) are nice, but can I get white lettered tires?

[NeilBlanchard]

Originally Posted by Thenorm

maybe i missed it... why do they want large diameter wheels?

I have always assumed that tires were lighter than wheels, so always go with the smallest wheel for lower rotational inertia.

also larger sidewalls are much more comforatble that lo profile tires.

is this a LRR thing?

The outside diameter of these 19" wheels is only a tad larger than a typical 15" diameter tire. So, they are significantly narrower - and this both lowers the rolling resistance, and reduces aerodynamic drag.

[P-hack]

Narrower tires by themselves do no translate to lower rolling resistance.

They do have less aero drag, and perhaps less rotating mass.

[NeilBlanchard]

These tires are designed to be higher pressure and to have lower rolling resistance:

Bridgestone Announces Development of “Large & Narrow Concept Tire”To Achieve Superior Levels of Fuel Efficiency and Safety | Corporate | Bridgestone Corporation

[P-hack]

lower rolling resistance than what? Conventional tires?!? 30% improvement in rr isn't so terrific in that case, been done repeatedly.

I don't see anything useful in the article, we already know higher pressure is good and metros came stock with 145s (10mm less than these) so aero disadvantage there. There is no point of reference in the article, crappy reporting and/or just a gimmick.

[Thenorm]

Originally Posted by P-hack

lower rolling resistance than what? Conventional tires?!? 30% improvement in rr isn't so terrific in that case, been done repeatedly.

I don't see anything useful in the article, we already know higher pressure is good and metros came stock with 145s (10mm less than these) so aero disadvantage there. There is no point of reference in the article, crappy reporting and/or just a gimmick.

thats what i've been trying to say.
i'm leaning towards gimmick.
it's so cars like the i3 can look all big wheels and performance-like, whereas it would be better served with lighter 15" wheels and conventional narrow LRR tires.

[NeilBlanchard]

The larger diameter also helps lower the rolling resistance.

[niky]

Since it's a Bridgestone press release, it's for general consumption... not for ecomodders, so they basically have to spell everything out for everyone else.

And I'm taking the 30% to mean improvement versus other Ecopias.

[P-hack]

Originally Posted by NeilBlanchard

The larger diameter also helps lower the rolling resistance.

Baseless, and increases inertia. Even race cars size their tires just big enough to fit the brakes. We don't need those kind of brakes.

Originally Posted by niky

Since it's a Bridgestone press release, it's for general consumption... not for ecomodders, so they basically have to spell everything out for everyone else.

Then why is it here?

Originally Posted by niky

And I'm taking the 30% to mean improvement versus other Ecopias.

Again, baseless. Crappy writing if that is the case (already too much of that on the web). The only thing this article is good for is wild speculation.