Smaller wheels highway question?

[Phase]

Originally Posted by aerohead

Unless the 16" tires have lower R-R, the smaller wheel diameter wouldn't necessarily have an aero advantage, and the difference in mass would hardly register on the radar, compared with the overall mass of the car.
On full BEVs, the single motor, large pack variant is typically chosen for highest range.
In town, the larger mass of the 17s would offset some acceleration penalty with more regen kinetic energy harvest.
Only the mathematics would tell.

I’d be getting ecopias. Idk what they come with but def would do low rolling resistance tires

Lighter wheels in city means less unsprung weight

[Ecky]

There's definitely a difference in feel, both in steering and handling, even with just a few pounds. How much of that translates into fuel economy I don't know.

[aerohead]

Originally Posted by Phase

I’d be getting ecopias. Idk what they come with but def would do low rolling resistance tires

Lighter wheels in city means less unsprung weight

If you weren't driving a hybrid, I'd say, 'go for it,' however, if you do it, you could inadvertently shoot yourself in the foot:
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1) As has already been discussed, the tire circumference remains the same regardless of wheel diameter. There's no difference in the tread's surface velocity-related hysteresis effects.
2) Since the dual-motor, 13.6-kWh plug-in is already 356-pounds heavier than the 'base' Prius, you're sweating some difference in polar-moment-of-inertia between the two different wheel/tire sizes, in comparison to an 11% increase in all-up mass.
3) Volvo proved that a 'heavier' hybrid can be 'better' than a lighter one, because of the regen phenomena, as, in the case of the PRIME, your getting 81.1% of the energy of 'braking' from an 11% 'heavier car.
4) You'd have to do a complete energy balance on the car to prove to yourself that you wouldn't just be p---ing away good money on an investment that might reward you with a 'zero' return on investment ( 'experience is a cruel teacher....gives the exam first, then the lesson' ).
5) The wheelhouses and wheels 'DO' add around 50% aero drag to a car.
6) And the 'exposed' portion below the belly constitutes about 80% of 'wheel drag.'
7) 'Windage/ Ventilation' drag has been reported at 'nothing' at 'low-speed', to 3% at 141-mph ( 227-km/h ) [ Tesla Model 3 in Germany, by Rob Palin ( aerodynamicist for Tesla Motors )].
8) If your car comes with the 'larger' wheels, something just beyond 'janky zipped-tied cardboard wheel covers' might be all you need to 'erase' the ventilation drag.

[Phase]

Originally Posted by aerohead

If you weren't driving a hybrid, I'd say, 'go for it,' however, if you do it, you could inadvertently shoot yourself in the foot:
--------------------------------------------------------------------------------------
1) As has already been discussed, the tire circumference remains the same regardless of wheel diameter. There's no difference in the tread's surface velocity-related hysteresis effects.
2) Since the dual-motor, 13.6-kWh plug-in is already 356-pounds heavier than the 'base' Prius, you're sweating some difference in polar-moment-of-inertia between the two different wheel/tire sizes, in comparison to an 11% increase in all-up mass.
3) Volvo proved that a 'heavier' hybrid can be 'better' than a lighter one, because of the regen phenomena, as, in the case of the PRIME, your getting 81.1% of the energy of 'braking' from an 11% 'heavier car.
4) You'd have to do a complete energy balance on the car to prove to yourself that you wouldn't just be p---ing away good money on an investment that might reward you with a 'zero' return on investment ( 'experience is a cruel teacher....gives the exam first, then the lesson' ).
5) The wheelhouses and wheels 'DO' add around 50% aero drag to a car.
6) And the 'exposed' portion below the belly constitutes about 80% of 'wheel drag.'
7) 'Windage/ Ventilation' drag has been reported at 'nothing' at 'low-speed', to 3% at 141-mph ( 227-km/h ) [ Tesla Model 3 in Germany, by Rob Palin ( aerodynamicist for Tesla Motors )].
8) If your car comes with the 'larger' wheels, something just beyond 'janky zipped-tied cardboard wheel covers' might be all you need to 'erase' the ventilation drag.

I wouldn’t get the plug in. It has terrible mpg once the battery is drained. YouTube videos show it getting about 40-45 mpg on the interstate

The 19 inch wheel Prius non plug in gets about 45 mpg at 70 miles per hour interstate based on multiple videos. That’s terrible.

Wayne at cleanmpg has shown several examples of the older Priuses with smaller wheels getting better highway mpg. Currently he’s been driving the base model 2023 version with 17 inch wheels and is getting 90 mpg but won’t state his speeds or driving patterns for some reason. He’s been advocating for smaller wheels also as an option out of the dealership.

One thing that’s nice about smaller tires, is they are much cheaper! So even if the gas mileage is barely a difference, the money saved by getting smaller tires every time you need new tires is a benefit right there

[Phase]

Apparently the diff between the 19 inch and the 17 inches is HUGE on the new Prius for steady state mpg highway testing

[aerohead]

Originally Posted by Phase

I wouldn’t get the plug in. It has terrible mpg once the battery is drained. YouTube videos show it getting about 40-45 mpg on the interstate

The 19 inch wheel Prius non plug in gets about 45 mpg at 70 miles per hour interstate based on multiple videos. That’s terrible.

Wayne at cleanmpg has shown several examples of the older Priuses with smaller wheels getting better highway mpg. Currently he’s been driving the base model 2023 version with 17 inch wheels and is getting 90 mpg but won’t state his speeds or driving patterns for some reason. He’s been advocating for smaller wheels also as an option out of the dealership.

One thing that’s nice about smaller tires, is they are much cheaper! So even if the gas mileage is barely a difference, the money saved by getting smaller tires every time you need new tires is a benefit right there

In his hypermiling hallucination he gets 90 mpg, just like an Dodge RAM 1500 EcoDiesel getting 124 mpg.
As far as the physics and thermodynamics of mpg goes, he's clueless.
I can 'get' 99-mpg in my friends 2009 Prius every time I drive it, but at a steady 65-mph, with the AC on, it's 43 mpg.
Context is everything. And I doubt you'll ever get any of it from Wayne.

[aerohead]

Originally Posted by Phase

I wouldn’t get the plug in. It has terrible mpg once the battery is drained. YouTube videos show it getting about 40-45 mpg on the interstate

The 19 inch wheel Prius non plug in gets about 45 mpg at 70 miles per hour interstate based on multiple videos. That’s terrible.

Wayne at cleanmpg has shown several examples of the older Priuses with smaller wheels getting better highway mpg. Currently he’s been driving the base model 2023 version with 17 inch wheels and is getting 90 mpg but won’t state his speeds or driving patterns for some reason. He’s been advocating for smaller wheels also as an option out of the dealership.

One thing that’s nice about smaller tires, is they are much cheaper! So even if the gas mileage is barely a difference, the money saved by getting smaller tires every time you need new tires is a benefit right there

1) Statistically, for 50-weeks a year, the plug-in will use zero gasoline. That's it's advantage.
2) What was his back-to-back, A-B-A testing results, on the same car, with the two different wheel/tire combos, on the same day and test route, compensated for changes in 'weather'?
3) Lets see if anyone else gets 90 mpg in that exact car.
4) The price of tires is not germane to the science of mpg.

[aerohead]

Originally Posted by Phase

Apparently the diff between the 19 inch and the 17 inches is HUGE on the new Prius for steady state mpg highway testing

Once up to a steady-speed cruise velocity, any difference in tire-wheel mass has virtually zero impact on mpg. As long as velocity is constant, which it ought to be, any difference in the amount of kinetic energy stored within each of the four 'flywheels' remains 'invisible' to the energy balance equation. To say differently belies Wayne's total ignorance of the topic.

[aerohead]

Here's another 'flag on the field'.
All new tires require a 4,000-mile break-in period before they reach their rated coefficient of rolling-resistance, and that coefficient falls over distance, ultimately reaching it's lowest possible value, when all the tread has worn away.
Car guru-wannabes need to arm themselves with these fundamental basics before ever opening their mouths, or risk losing all credibility, of which, it's my opinion that, Wayne has none.

[Phase]

Originally Posted by aerohead

Here's another 'flag on the field'.
All new tires require a 4,000-mile break-in period before they reach their rated coefficient of rolling-resistance, and that coefficient falls over distance, ultimately reaching it's lowest possible value, when all the tread has worn away.
Car guru-wannabes need to arm themselves with these fundamental basics before ever opening their mouths, or risk losing all credibility, of which, it's my opinion that, Wayne has none.

Do you think engineering explained had credibility?

https://youtu.be/NYvKxsYFqO8?si=4L4M45SEzCVrZW_H

Skip to 7:30 in the video. He straight up states that Tesla itself has different ranges submitted legally for each tire size at a STEADY STATE speed also.

Explain that too, regardless of your beef with Wayne