Taller tires = more range on highway?

[coloradoman]

If I get a taller tire than the stock tire that comes on the stock 16in steel rims, will this improve my range at highway speeds? Since the engine would be rotating slower because the tires are bigger is my thought. But I have no idea.

[alozzy]

No, if anything your mileage might get a little worse. Higher profile tires offer a cushier ride but don't handle as well in corners.

[estomax]

The electric motor efficiency is very high across RPM range, unlike an ICE.

Look on page 11 here for a Leaf motor map:
https://www.energy.gov/sites/prod/files ... 2013_o.pdf

taller tires will reduce RPMS, which will reduce inverter efficiency very slightly, and probably not change motor efficiency significantly. They will make your car taller and reduce aerodynamic efficiency though, as well as add increased rolling resistance from more mass to rotate (taller tire = heavier).

Marko

[Oilpan4]

On gas burner cars taller tires usually gets better mpg.
On electrics, I don't think anyone has tested it.
Inverter and motor efficiency is a little different than brake specific horsepower consumption.
So many variables it would need to be tested to make sure.

[knightmb]

If I get a taller tire than the stock tire that comes on the stock 16in steel rims, will this improve my range at highway speeds? Since the engine would be rotating slower because the tires are bigger is my thought. But I have no idea.

Napkin answer, "No", the car was probably optimized for the stock tire size. Long answer, physics plays a part, energy in, energy out. Increasing the travel distance for each rotation of the tire takes more energy, thus the extra distance gained is cancelled out by the extra energy needed to complete the rotation. You can feel this effect yourself on a bicycle with gears. You pedal harder but travel faster in the higher gears.

Speedometer also gets inaccurate since it was set for the smaller diameter, you will drive faster than it shows and thus use even more power due to air resistance.

[DougWantsALeaf]

If you can get a super light rim, you may be able to reduce unsprung weight, which would improve efficiency.

[powersurge]

My answer.... You can go up about 1 size on the middle number (e.g., 215 55 16 TO 215 60 16), but not much.

If you go too high in tire size, the tires will rub and make noise against the suspension when you go over bumps or turn the steering on turns....

You will get more distance per rotation of the tire, but it will not be a big difference....

The best reason to do this is when the stock tires are very sensitive to any bumps or cracks in the road because the are low profile (e.g, not much distance between the road and the rim, like 45, 50, 55s (second number). I have improved the ride by going up one size of the middle number.

PS - Tire places do not like to sell you a different size tire than what their book says...

[PrairieLEAF]

The selling dealership put 215/65R16 on this one (it's probably what they had in the back). I've never had any tire contact, that I could tell, and the speedo reads about 4% low.

I think since the motor seems equally happy at any rpm within its operating range, that taller tires don't help an EV maintain speed on the highway. I presume that taller tires require more energy to accelerate, and slightly increase acceleration times.

I'm curious which way my long term efficiency goes on its next tire set (probably stock size). Then again, the rolling resistance of a different tire may matter more than small differences in size.

[powersurge]

4% error is acceptable for the speedometer/ odometer..

All cars have some error.. 4% is a difference of 200 feet per mile.. not that critical. You can change the tire diameter slightly with your next set?? But is it really worth it?

Nothing in life is exact. You just have to decide which things must be exact...

Like your bank account and your wife's # of boyfriends...

[Oilpan4]

If the range isn't hurt the next size up tire may be cheaper.
For example my wife's old car took 215/55R16. I went to 215/60R16 and saved $20 per tire. Same tire make and model of tire, just a different size.
Got about 5% better highway milage, but that's on gas burner that did about 90% of its miles on the highway.