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Tires

Discussion in 'Gen 3 Prius Main Forum' started by tonyspin, Oct 29, 2013.

  1. litesong

    litesong Active Member

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    Oh, make that 19 tires....& 5 Goodyear Eagle GT tires. Just got a never-mounted spare Eagle GT for $40. Love the smell of new rubber in the morning!

    I've mentioned (somewhere), since I've started using "used" tires that I find more "made in the U.S.A" tires than people find in new tire stores. In the past week, I got 3 "never-used" new tires(one free), two of them, "made in the U.S.A.". All right!!!! The last one was a Goodyear Eagle GA, built in 2014..... came mounted on a Lexus wheel that will fit my Hyundai Elantra.
     
    #61 litesong, Apr 8, 2019
    Last edited by a moderator: Sep 26, 2019
  2. Robert Holt

    Robert Holt Senior Member

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    Not sure that stiff sidewalls would give better mileage! My impression is that with thicker sidewalls the rubber hysteresis losses are higher and total rolling resistance would generally increase rather than decrease. One point is that I believe “run-flat” tires have thicker sidewalls and also generally have lower mpg results than the equivalent normal tires. Similarly, I vaguely recall that early bicycles with solid-rubber tires were quickly supplanted by the pneumatic tire (1880-1890s?) as the effort of pedaling was lower. Anybody find scientific evidence on this?
     
  3. padroo

    padroo Senior Member

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    Run flat tires are also heavier.
     
  4. litesong

    litesong Active Member

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    Yes! Is it OK to have a run flat tire & a regular tire on the same axle? Or to have two run-flats up front & regular tires on the back?
     
  5. padroo

    padroo Senior Member

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    Where did you ever hear that?




    Posted via the PriusChat mobile app.
     
  6. Robert Holt

    Robert Holt Senior Member

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    Wowzer, I would NOT want to do that!. In my experience, really odd , unpredictable things happen with mixed sets of tires when you really slam on the brakes or are getting near the adhesion limits in a turn. (Unpredictable = BAD!)
    Look, IIRC Porsche requires not only that you cannot repair a flat for the tires on their cars, but that you must replace THE ENTIRE SET OF 4 TIRES whenever you have a puncture in any of them. That is ungodly expensive and one reason I do not buy Porsches, but the safety logic is sound in that you have to have completely matched sets of tires with even tread wear and absolutely correct inflation pressures to have predictable handling.
    Run flat tires are, if I understand correctly, built with stiffer sidewalls than normal tires, and that would predictably result in a different contact patch on the pavement as you stress the tires sideways in a hard turn. Similarly, the stickiness of the rubber compounds used in the run flat and regular tires may differ. In either case with sideways G force one tire would then suddenly break loose before the other one, which would then engage the stability control system and all heck would break loose. In my experience, when the Prius stability control system engages in a hard turn, the result is to accentuate drift to the outside of the turn. If you have plenty of space such as a race track, that may not be a problem, but on most normal streets there are obstacles at the outside edge of curves such as guardrails, trees, or pedestrians that you wish to avoid contact with. Please be careful.
     
  7. padroo

    padroo Senior Member

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  8. Robert Holt

    Robert Holt Senior Member

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    Na so was! Irgendwo im Deutschland, nicht wahr?
    Danke schön, weil es zeigt die Unterschiede sehr klar.
    That picture does substantiate that the run flat tire cross-section has a much thicker sidewall that would behave differently in a turn with high lateral forces. Just if you mix and match tires, please expect unpredictable traction and stability qualities in critical situations.
     
    WilDavis likes this.