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Any Experience w/ 195/65R15 Tire Size??

Discussion in 'Gen 2 Prius Main Forum' started by Infidel, Oct 29, 2007.

  1. Infidel

    Infidel New Member

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    Well the Integrities are coming up on 45K miles, and I'm looking at replacements in the near future. I'd like to upgrade to a 195-series for the extra stability. After reading all the tire posts in the forums, it seems most people go with the 195/60 as a close size match. But I am tempted for the little extra diameter of the 195/65's (~ .25 inch on the radius) with a 2% overdrive effect (speedo under-read).

    I think I saw one post of someone who did this and reported a mileage hit. Has anybody else tried this with acceptable results? A little extra ground clearance might keep me from scraping that chin fairing on those pesky parking slot curbs, and will correct my speedo which now reads about 1% fast according to the GPS.

    The standard 185/65 Integrities have held up well, but the handling is a little squirrely at speed in crosswinds. Thus the desire to bump up the width a bit.

    Am thinking of either Michelin's ( HE or X's) or maybe the Pirelli 3000's.

    Any advice appreciated! Thanks in advance.

    Infidel
     
    #1 Infidel, Oct 29, 2007
  2. patsparks

    patsparks An Aussie perspective

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    G'day Infidel
    Not sure going to larger diameter tyres is a good move, this will put additional load on the HSD, reduce acceleration, raise the ride height allowing more air under the car, less responsive handling due to sidewall flex and upset the speedo and odometer.
    What would you gain from doing it? Nothing.
    The HSD will keep the engine revs as low as practical anyway so there is no value in overdrive from the tyres unless you are going to be trying for a land speed record or something in which case larger tyres may raise the top speed slightly.

    I think you will find that with stock diameter tyres the ICE revs can be as low as 880RPM at 70 MPH which is better than a V8 in overdrive. The difference with HSD is the revs increase automatically when you need more power for that slight hill without any bumping or jerking of an automatic transmission shifting down. The computer can select the optimum "ratio" all the time, there is no need for a margin for changing road conditions to increase smoothness as long as there is enough power to the wheels. I think with larger wheels the ICE revs will be the same (or higher to account for slightly more wind drag) because the power demand will be the same so there is no real overdrive affect.

    I should add I am no expert in this field specifically, so I stand to be corrected by an expert if I'm wrong.

    Aussie release Prius have 195 60H 15 michelin Energy tyres fitted and I'm happy with them.
     
    #2 patsparks, Oct 29, 2007
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