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The effect of trim rings on tire balance

Discussion in 'Gen 2 Prius Technical Discussion' started by JamesWyatt, Jul 20, 2008.

  1. JamesWyatt

    JamesWyatt Señior Member

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    I've always been one of those people who could detect a miniscule amount of incorrect wheel balance. Having taken the trim rings off and put them back on several times over the last few weeks I have come to the conclusion that the tire balance is better with them off. I have new Comfortred tires, and with the trim rings on it rides great, but with them off, it rides absolutely smooth as glass. I know this is subjective, but I can tell a difference.

    Even though this is a very subjective suggestion, it does make some logical sense. I've always watched the screens at Discount tire when they balance my tires, because on the SUV I used to own (oversize A/T tires) even the slightest variance from "0" on their machine would give me a ride quality I could detect as inferior, even at slow speeds. Tires that are even slightly out of balance will not take imperfections in the road the same way as perfectly balanced ones do.

    Some of the weights they use to balance tires are pretty small. It seems logical to me that adding the weight of a plastic trim ring could possibly alter the tire balance ever so slightly.

    If we assume for a minute that at least in my case, the tires are balanced better without the trim rings, then why? I could have one or any number of the trim rings that are "out of round" or not perfectly weighted from one side to the other. I'm not sure if the cutout for the valve stems would account for enough weight to alter the balance with any significance. Another possibility is that at speed the trim rings can warp slightly due to centrifugal force. Of course, if the trim rings are not perfectly weighted all the way around, that would worsen the effect.

    Someone I know will tell me I'm crazy, and they're probably right. However, I would swear the car just feels smoother... almost lighter... with them off.

    :behindsofa:

    I'm sure for safety and insurance reasons, you could not get a tire balancer to balance the tires with the trim rings on, but it seems like a logical thing to do. Since they're only rings, you should be able to leave them on. Has anyone had their tire shop not notice that the trim rings come off an just balance the tires with the rings on???
     
    #1 JamesWyatt, Jul 20, 2008
  2. patsparks

    patsparks An Aussie perspective

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    Well actually you can balance wheels with the trim rings on.
    Many modern balancers are hand spun so only turn at low speed.
    It would be a pain to remove and replace them to install weights but neither dangerous or impossible.
     
    #2 patsparks, Jul 20, 2008
  3. donee

    donee New Member

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    Hi James,

    The trim rings are symetrical except for the hole for the valve stem. That absense of plastic there has to be a quite minisicule imbalance. I doubt highly it could be noticed.

    While the weight of the trim ring all lumped togehter in a piece of metal could imbalance a tire, the trim ring is rotationally symetric and the weight is evenly distributed. So, no problem.
     
    #3 donee, Jul 21, 2008
  4. richard schumacher

    richard schumacher shortbus driver

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    Trim rings are not necessarily perfectly symmetric and balanced by themselves, but the bigger point is that wheels don't get balanced axially because axial imbalance has negligible consequences; wheels are only balanced radially. Any radial imbalance contribution from the trim rings gets accounted for during the usual balancing process (assuming that the rings are in place during the balancing), and any axial imbalance is ignored.
     
    #4 richard schumacher, Jul 22, 2008
  5. JamesWyatt

    JamesWyatt Señior Member

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    Right, but that's just it. The rings were not in place during my last balancing (new tire install).
     
    #5 JamesWyatt, Jul 22, 2008
  6. morpheusx

    morpheusx Professor Chaos

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    quite honestly if you can notice a difference with them on or off I'd leave them off. I wonder if you notice when you have a loose stone in your tread as well. :)
     
    #6 morpheusx, Jul 22, 2008
  7. JamesWyatt

    JamesWyatt Señior Member

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    Yeah, I'm leaving them off. Hah-ha, funny! I guess I might feel them if they were all the way around the tire on one tread grove ;)
     
    #7 JamesWyatt, Jul 22, 2008
  8. richard schumacher

    richard schumacher shortbus driver

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    That's all you can do unless you want to have the wheels balanced again.
     
    #8 richard schumacher, Jul 22, 2008
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