1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Tire size vs. MPG

Discussion in 'Gen 3 Prius Fuel Economy' started by Bucco, Mar 4, 2014.

  1. Bucco

    Bucco New Member

    Joined:
    Dec 18, 2013
    21
    6
    0
    Vehicle:
    2014 Prius
    Model:
    Four
    I have read in many posts that you don't get as many MPG with the 17" tires as you do with the 15" tires. I am curious why this is. I understand why the 15" tires give a softer ride (more air in them) but isn't the circumference the same on both tires? If the circumference is the same (which I'm not sure about) why the MPG difference?
     
    #1 Bucco, Mar 4, 2014
  2. jhinsc

    jhinsc Senior Member

    Joined:
    Nov 25, 2010
    1,167
    259
    0
    Location:
    South Carolina
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
    Wider contact patch on the road with 17's vs 15's means increased rolling resistance, and slightly less aerodynamic, again due to wider tire and different rims would be my first guess.
     
    #2 jhinsc, Mar 4, 2014
  3. Easy Rider

    Easy Rider Active Member

    Joined:
    Feb 9, 2014
    982
    210
    0
    Location:
    N. Central Florida
    Vehicle:
    2013 Prius c
    Model:
    Three
    It's been discussed in another thread here just in the past week or so.

    There is nothing inherently different about all larger wheels that give poorer gas mileage.
    In the case of the stock Toyota offerings, the 17s seem to be heavier overall (when you add the rim and tire) and
    they have a wider footprint with higher rolling resistance.

    It could go the other way though, if the larger wheels were lighter and the tires used were a low rolling resistance type.
     
    #3 Easy Rider, Mar 4, 2014
  4. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

    Joined:
    Oct 28, 2010
    7,855
    6,658
    0
    Location:
    Redneck Riviera (Gulf South)
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
    Bigger rims (and the) tires tend to be heavier.
    They also tend to have a bigger contact patch resulting in increased rolling resistance, and bigger rims usually have to push more air out of the way.

    You can mitigate some of these factors with alloy rims, low profile tires, ground effects...etc but those efforts will also give corresponding results in the 15" world.

    SUV or Prius?
    Bigger isn't always better. ;)
     
    #4 ETC(SS), Mar 4, 2014
(You must log in or sign up to post here.)