Are these possible? Will this drop the MPG?

The larger wheels will definitely reduce MPG several points. It clearly shows in trims with larger wheels from the factory.

Not sure lowering the car will create a noticeable change. Sway bar ought to be nearly negligible, no worse than simply throwing in the same weight of cargo in the trunk.

All these mods are possible, numerous readers here (not me) have done them.

Posted via the PriusChat mobile app.

 

None of that will accomplish anything positive, in my view:
Lowering will increase scraping on drivways in an already-low body.
Larger wheels will harshen ride and increase potential for tire damage.
Stiffer sway bars may screw up the stability control system.

 

lowering might increase aero and thus mpg

 

In almost every case, the metal wheel is heavier than the air inflated tire. So larger wheels tend to weigh more than the same sized smaller diameter wheels. Because they rotate, the weight 'counts' more than the same weight in the body.

Rotational inertia (article) |Khan Academy

There exist 'forged' wheels, much lighter than the cheaper 'cast' wheels, expect over $1000 per wheel.

Classic Series - 301 | HRE Performance Wheels

As you can imagine, the improved MPG will never pay for this lack of weight.

 

lowering the car has a small decimal value increase on aero performance - because its a slow car. Doing so just reduces the volume of air that enters at the underside of the car to road pavement.

If you lower the prius, you better have stiffer springs or shock absorbers that arnt as soft as OEM.

suspension/chassis mods are just that. They modify the suspension and chassis ... they may... have a slight increase in fuel efficiency since you don't need to let off the accerlator pedal as much since the car will behave "better" around turns. Meaning the car will not need to put the energy back in to reach speed limit.

After chasis suspension mods. you'll can reduce maybe 8-15% less pedal travel going around turns. there ya go. fuel saved.
but at what cost ($$$)

Increasing rim size will decrease mpg. 1 to 2 mpgs

 

didn't toyota lower prime/gen4?

 

My understanding is the standard Prius has no rear sway bar - adding one would stiffen the suspension, but also add weight. All your mods may improve handling, but nothing else.

 

IIRC, Gen 4 is 5.1" and Prime is 4.8"

Edit to add:
Oddly, I seem to scrape less with the Prime than I did with the PiP. Perhaps I'm just more cautious.

 

I'm running 18x9 wheels with 235/40/18 tires and my mileage went from avg 50mpg to 47mpg. I also installed roof racks form my mountain bike and that brought it down to 45mpg.

 

Do the tires on a larger diameter wheel also have larger outside diameters? If so, that would change lower the mileage reading hence the calculated mpg.

 

I'm pretty sure that the only requirement for the OD of the tires is that it is greater than the inside diameter. Sidewall heights vary. That's how a Prius can run fine on 15" or 17" wheels.

 

In all my years of car ownership and custom rims, I always went for custom rims because, heck, they just make a car look so darn good!! I will add, that if you really want to save gas and get good looks, you have to pay for the light but strong rims. It is very expensive, and rarely gets you the money back due to in 5 years your rims are outdated and usually people change them out for another style. That is what I did.

So, I wound up just doing it for looks. If you don't buy the expensive ones, you will get "stress fractures" inside the rims that eventually lead to cracks. On my Scion, I had these really cool looking rims that matched my car color, but man, 5 times a year I had to take the rims in to this place to re-weld, sand, polish and balance the rims due them cracking just from day to day driving. Once you start a fracture, its game on in keeping up with the crack patrol that comes afterwards! So, for me, it was and will continue to be "rims for the looks" and nothing else. And if I got the money to "burn" throught the maintenance, cool, if not, I will just stay stock. This is why I have kept my stock rims.

 

See Tyre Size Calculator
15 inch tire size 175/65R15 OD is 24 inches
18 inch tire size 235/40R15 OD is 25.4 inches
So 18 inch tires rotate less times per mile
(24/25.4)*50 = 47.24 so your 50 mpg car appears to be getting 47mpg because the tires are rotating less times. That is, when the odometer says you have gone 47.24 miles you have actually gone 50 miles.

 

OP,

Go ahead and do all the things you've listed, your driving enjoyment with the way your car looks and handles will go WAY UP.

I personally run a Non LRR Ultra High Performance All-Season 205/50-17 tire on a 17.0 lbs 17x7 wheel. My Prime currently shows me a 27.4 mile range on my fully charged battery and when I was on my last long distance trip, I averaged 49 mpg while driving at roughly 70 to 75 mph on the ICE.

My increased handling and wet* & dry* grip are excellent, my driving enjoyment is Much Better and I only changed out the Wheels & tires.


Rob43


* This is a major safety increase when compared to the original equipment.

 

But the question was:

The answer is that they may or may not have larger outside diameters than the ones on a smaller wheel. It depends on what tire is selected.

 

You might see a slight mpg improvement from this, by reducing the amount of air flowing under the car.

They won't. They simply reduce body roll, which will help stability control.

With larger wheels, you typically will use plus sizing, where the tire aspect ratio is also lower on the larger wheel. The goal is to get the rolling circumference the same, thus no affect on the odometer. As an example, the Yokohama Avid Ascend GT in 195/65R15 results in 830 revs/mile. The "Plus 1" size for this tire would be 205/55R16, which also results in 830 revs/mile. You can swap the larger tire/wheel combination and your odometer will be unchanged.

Using a static OD is less accurate than using revolutions/mile.

 

15 inch tire size 175/65R15 842 rev/mi
18 inch tire size 235/40R18 794 rev/mi
(794/842)*50 = 47.1
Pretty much the same as using OD

 

Where do you get your completely Unrealistic tire numbers from, they're both misleading & bad information.

1) Every source I look at for a Prius Plug-in shows a 195/65-15 tire size, this is 25.0" OD.
www.google.com/search?q=2012+pruis+plug+in+tire+size&rlz=1CARAWP_enUS752US752&oq=2012+pruis+plug+in+tire+size&aqs=chrome..69i57j0.20113j1j8&sourceid=chrome&ie=UTF-8
2) You state that a 175/65-15 tire is 842 Revs per mile, this information is wrong, Tire Rack has them listed at 864 to 869 revs per mile.
3) Using the 235/40-18 data point of 1 or 2 people out of millions is not realistic.


Rob43

 

Ok.