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  1. #1
    Registered Member One Ring
    Join Date
    Mar 29 2012
    AZ Member #
    United States

    Paranoid Question

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    So driving up to pick up some parts today I had a flat and put on the full-size spare without thinking (I just recently bought the car). I drove for 10 miles or so and it felt like I felt a bit of a wobble or shimmy in the front end so I pulled over. To my dismay the spare had a 235 series tire mounted on it, whereas all my other wheels had 225 series tires on them.

    I immediately plugged the hole in the flat and put it back on. I still felt some wobble/shimmy but after a few miles it stopped. This could be all in my head...I'm sure my tires aren't balanced properly but I just want to make sure.

    Will driving for ~10 miles with one tire being 10mm bigger cause any significant damage to the differential? I'm trying to rationalize it by thinking about it being similar to a very long extended 5 degree left turn.


    **EDIT** So I did a bit of calculation...

    235/45/17 = 25.327 in diameter and 79.567 in circumference.
    225/45/17 = 24.972 in diameter and 78.452 in circumference.
    Difference is 0.355 in diameter and 1.115 in circumference.

    I feel like such a small difference being run for only 10 miles or so could not grenade a diff. I also hear no moaning, it's just the shimmy that had me worried, but please correct me if I'm wrong.
    Last edited by Duo Maxwell; 03-29-2012 at 02:28 AM.

  2. #2
    Active Member One Ring
    Join Date
    Mar 26 2012
    AZ Member #

    If you only put down 10 miles you did not hurt anything. The thing you cannot do is run that for an extended period of time. If you do that what happens is the diff gear want to spin at two different RPM's so they are constantly in a battle with each other which will destroy things if left that way. A shimmy would be more of a tire problem like out of balance issues. I would say you need a new spare.


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