About to pick up my Prius...question about wheel replacement and MPG

A tire/wheel combination that weighs more (especially at the outside, weigh at the hub is not as important) uses more energy to rotate, and stores more energy you need to overcome when braking.

Size is not 'really' important, weight is, but all things equal larger is heavier.

 

Have you considered simply removing the plastic hubcaps? You may like the look of the alloy wheels underneath better than the stock hubcaps. Way cheaper than replacing wheels and tires, and no measurable effect on mpg.

Photos here:
http://priuschat.com/forums/gen-iii-2010-prius-accessories-modifications/89666-hubcaps-2.html

 

Welcome to PriusChat:welcome:

I'm thinking tire pressure, rather than wheels, may have more impact on MPGs. There's lots of thread disccusion about increasing pressure for improved MPGs.

Have fun with your new Prius.

 

Having been through all of this I can honestly tell you that yes you will lose some MPG by switching to a larger wheel. How much you lose will depend on a few factors.

#1 What size wheel you are upgrading to

#2 What size tire you are upgrading to

#3 What does the new wheel weigh compared to your OEM wheel

#4 What brand/model tire are you upgrading to

With this in mind if you want to reduce your MPG hit as much as possible while still upgrading to a nice wheel/tire combo then I would suggest the following:

#1 Go with a 17" or even 18" wheel. THE 18s look better on the GenIII but tire choice is limited.

#2 Stick with the narrowest tire you can correctly fit on the wheel. I.E. don't purchase a very wide wheel or else you'll need a wider tire and that increases ground friction and reduces MPG.

#3 Buy the lightest wheel you can afford. Something under 20lbs will work but the closer you can get to 15lbs the less your MPG will suffer.

#4 Purchase a Low Rolling Resistance tire if possible. They come in many sizes and you do not have to suffer from reduced treadwear or traction anymore. The new tires are great and will save you money in the long run. Quality LLR in the 17-18 inch size include the Michelin Primacy MXM4 and the Continental ContiProContact or DWS. Here is a short list of available LRR tires.

I've run non-LRR tires on my 17s for quite some time now and everytime I swap from my OEM 15s with LRR tires to my 17s with ultra-high performance tires my MPG drops by about 6mpg. While this is not a significant loss in terms of money per year I do find it very annoying to drop below 50mpg so for me it was worth it to purchase new tires (the current ones are bald anyway) that will increase my gas mileage. The new tires (Primacy MXM4) were priced similar to other quality non-LRR tires so it's not costing me any more for the extra efficiency.

So it's up to you if you want to swap to a larger wheel but I will say that despite some MPG loss it is totally worth it if you want a sporty look and MUCH better handling.

 

I will probably replace my stock 15s with 16s. Searching for wheels and will definitely try to stay with 195-205 width LRR. Weight is huge as is inflation pressure. I'm fairly convinced that tread width is too, more to push on the pavement.
Welcome and good luck

 

Proper inflation does play a part in fuel economy but do not underestimate the tire construction itself. No matter what pressure I run in my Kumho Ecsta ASXs they still suck for rolling resistance. My wheels weight the same as my OEM 15s so the loss is all tire.

 

Although I and many other might be concerned w/the mileage drop due to larger wheels and tires w/higher rolling resistance, the actual effect in terms of # of extra gallons consumed may not be as large as you think. See http://priuschat.com/forums/other-c...eage-no-its-your-gallonage-really-counts.html.

Example:
If you drop from 50 to 45 mpg (10% drop), over 100 miles, you'd have consumed 0.22 gallons more.
If you drop from 20 to 18 mpg (10% drop), over 100 miles, you'd have consumed 0.56 gallons more.

 

Read Below! Good Luck

Newbie here, bought rims/tires, OMG, what a mistake | PriusChat

 

It sounds like you are picking up a leased Prius. Starting with a used Prius, especially one that has a good service record is a great way to start. Now to answer your questions.

REPLACE WHEELS?

I have no strong opinions. I notice there is a company making carbon-fiber wheels, lowest possible weight, that might make a small reduction in vehicle weight. If it is just for looks, I would recommend survey wheel covers first.

Over in ecomodder.com there have been a number of 'home brewed' moon covers including some pizza pan covers. The advantage is they reduce the amount of air entrapped in the wheels. As for esthetics, Prius people seem to think this is what is important:


REPLACE TIRES?

This is an area where you'll find agreement on replacing the tires but opinions vary on which ones. Hopefully the folks that have other favorite brands will join in but let me share my choice.

I'm using Sumitomo T4s:

• Toyota sold them as replacements for the original tires (second flat forced 4-tire change early)
• Maximum sidewall 51 psi which is what I run
• Tire revs/mile brought the indicated speed and MPG to ~0.4% of GPS true value
• Poor ice performance is not a problem in North Alabama where everything shuts down and we stay home if there is significant ice or snow events

I also use over-sized T4s on our 2003 Prius which has the effect of giving me ~6% over-drive and better handling. The larger diameter improves straight-line stability of that car. The indicated MPG and speed are off but using a calibration correction factor, I have am able to exploit 40 mph posted roads as if I were driving at 38 mph and use the hybrid control laws more consistently (aka., slightly improved mileage.) Using over-sized tires is an advanced subject so I'll stop here.

GOOD LUCK!
Bob Wilson