Tire size question

Discussion in 'Gen 2 Prius Main Forum' started by Theotis, Feb 23, 2019.

  1. Theotis

    Theotis Junior Member

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    Greetings! I did a search but didn't see the exact answer to this.
    Have a 2008 Touring OE 195/55/16 Pressure 35F/33R
    I have some great Michelin XI3 snow tires on rims (from 06 Corolla) with almost no wear- size 195/65/15 30/30pressure. Rims are 15x6 5-100.
    Can i safely use the Michelins/rims on my 08 touring? I'm not concerned about slight speedometer/odometer differences.. What PSI would be correct?
    Thanks for any advice! This is a great forum.
     
  2. Theotis

    Theotis Junior Member

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    Help out a new prius brother?
     
  3. dolj

    dolj Senior Member

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    If the lug holes in the wheels match the studs on the wheel hubs, then go for it.
    The same 35 PSI Front/33 PSI Rear. Then go from there, after examining the tread water pattern over 5-10,000 miles.
     
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  4. Skibob

    Skibob Senior Member

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    The tires should work fine, they are just slightly bigger than the 15’s on standard model (185/65R15). Plenty of people use that size. What I don’t know is if the rims will properly fit. A different offset might cause a rub or something. Standard rim size is 15 x 6JJ if that helps.
     
  5. mpg_numbers_guy

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    35 and 33 PSI? That's basically flat..
     
  6. Skibob

    Skibob Senior Member

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    That’s the recommended pressures for the 15 inch tires. Would you really want to overfill snow tires to use in the winter?
     
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  7. dolj

    dolj Senior Member

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    As pointed out by Bob above, your “Practically flat” is the manufacturer’s recommended.

    Most people who think they make amazing fuel economy leaps using over-inflated pressures, actually get improvement due to the fact they start to pay attention to their tires and stop running them under-inflated. Fuel economy suffers exponentially for every 1 PSI of under-inflation.

    After careful and documented experimentation, I haven’t found much advantage to over-inflating Prius tires (above recommended), except prematurely wearing them out by worn centers. I reckoned that I could have got another year out of the set if the tires had worn evenly over the whole tread. The cost of prematurely worn tires outweighed the saving in fuel saved running over-inflated tires.

    Of course, YMMV and you and anyone, in fact, is free to run their tires as they choose.

    Tire over-inflation has been done to death, here and other sites, and I am not about to get into an argument with you about it. I have said my piece and the reasons why. I think all rational people can make up their own minds.
     
    #7 dolj, Feb 25, 2019
    Last edited: Feb 25, 2019
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  8. Skibob

    Skibob Senior Member

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    Know how many MPG a Prius gets with overinflated snow tires? ZERO after you hit that tree. :whistle:
     
  9. Theotis

    Theotis Junior Member

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    Thanks guys! Will double check the rim size, but i think they are good-
     
  10. mpg_numbers_guy

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    No, but the sidewall max is 44 PSI generally. :)

    If you own a Prius, you are generally concerned about fuel economy, so why take away from it?

    Inflating tires to sidewall max has shown a measured increase in fuel economy - enough to offset any slightly shorter tread life, but I understand if some are not brave enough. Some people report better treadwear at sidewall max.

    Know how many MPG a Prius gets with underinflated snow tires? ZERO after you hit that tree. :whistle:
     
  11. Mendel Leisk

    Mendel Leisk Underfoot

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    There's also increased stress to bearings and suspension components. And loosened fillings.

    I'll just quote that bit, suffice to say the rest get's increasingly laughable. If you want to run at max sidewall pressure fine, but advocating it for others I think you'll find you're in the minority. My preference is to go a few pounds over the manufacturer's recomendation (on the driver's door opening decal), 2~3 pounds at most. I also tend to set the rear the same as the front, just to simplify rotations.
     
    #11 Mendel Leisk, Feb 26, 2019
    Last edited: Feb 26, 2019
  12. Usle

    Usle Member

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    The snows are a good fit, prii want 25" diameter tires to give correct speed and odometer readings, your 16" wheels are 24.4" as are the 185/65-15" tires prius sold the regular gen2's with, so....go with the 15" snow tires.

    And...pump them to 40, sidewall recommendations are 1/2 the bursting strength(just like bicycles), a firmer tire handles better, gives better mpg's and lasts longer.

    When you replace your 16" tires get 195/60-16" tires with a diameter of 25.2", a tiny bit larger, better mpg's.
     
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  13. Skibob

    Skibob Senior Member

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    Have you ever heard of a contact patch? Property inflated tires have a contact patch the manufacturer deems safe for the car. Overinflated tires reduce that area. Do you really think reducing the contact area of a snow tire is a good idea?
     
  14. mpg_numbers_guy

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    Really only if you do some insane pressure like 80 PSI or higher..

    Oh, I'm sure I'm in the minority, but that doesn't automatically mean I'm wrong. If people want to deal with lower fuel economy due to underinflated tires, then it's their choice, but to simply downvote someone's opinion because you don't like the idea is just disrespectful.

    Run your tires low if you want. I'll run mine high if I want. You may post your recommended pressure, and I'll do the same. 'Nough said.

    Then buy slightly wider tires and inflate them up if that's a major concern to you. Manufacturers run excessively wide tires for comfort and handling. Most cars do fine with tires narrower than spec.

    And yes, narrower winter tires provide better traction. Narrower winter tires cut through the snow better and have a lower risk of slipping due to more weight being on a smaller contact area.

    ......and I think we've digressed enough from the topic of this thread..
     
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