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Thread: Wrong size tyres fitted

  1. #1
    Join Date
    Jul 2012
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    Australia
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    Wrong size tyres fitted

    My wife took our 2006 smart for two to the Tyre place yesterday for 4 new tyres. They also replaced a tail light globe. When she drove off the engine light came on followed by numerous other brake related lights. Turns out they put the wrong size tyres on (larger). Would this be the cause for all the lights on the dashboard? Will this have caused any major problems. I know smart cars are smart but do they know when they have the wrong size tyres on?

  2. #2
    Join Date
    Jun 2011
    Location
    Stafford UK
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    Yes it will cause the lights on the dash to come on.As the reluctor rings will be going round faster and the ABS will think your car is spinning its wheels thus cutting engine power etc.You need to put the correct size tyres on.Or if you up grade your rims to a bigger size you need to alter the tyres profile EG 40 instead of 50 profile.To give the same rolling diameter

  3. #3
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    Jul 2012
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    Thank you. You really are Robert the great. Puts my mind at ease knowing its an easy fix.

  4. #4
    Join Date
    May 2009
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    London
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    just out of interest (without taking over the thread) would it be possible to reteach the sam unit to accept a different tyre size?

  5. #5
    Join Date
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    Location
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    I believe there is a setting in the MB STAR diagnostics for wheel/tyre size.
    By default the TRUST+ system will accomodate a certain change in tyre size but it has limits.
    e.g. I upgraded my 16" spikelines to 17" monoblocks without making the changes on the ECU. The rolling circmference has increased slightly but not enough to throw a fault.
    ==============================
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    ==============================

  6. #6
    Join Date
    Sep 2009
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    Surely the question should be Why did the Tyre place put the wrong size Tyres on? It is obvious they did not know what they were doing,so you should go back and get them to put the correct tyres on,or get a refund.

  7. #7
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    Apr 2009
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    Quote Originally Posted by NeilP View Post
    just out of interest (without taking over the thread) would it be possible to reteach the sam unit to accept a different tyre size?
    Battery disconnect has been known to deal with small discrepancies on 450 and Roadsters.

  8. #8
    Join Date
    Mar 2012
    Location
    Daventry
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    Shouldn't be a problem if all 4 tyres are changed to a larger or smaller size - the problem is when 2 are changed to a different size because the processor is looking for the same number of pulses from each corner (within parameters which account for tyre wear) two larger tyres will give fewer pulses for the same distance covered as two smaller tyres

  9. #9
    Join Date
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    Quote Originally Posted by bob-in-dav View Post
    (within parameters which account for tyre wear)s
    That part not infallible though. It can get caught out.

  10. #10
    Join Date
    Jan 2009
    Location
    Rugby
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    I've got larger tyres fitted without any problems. What size did they fit??

    Anastasia
    Mr Poo - Mk5 450 Pulse
    Honky - 451 Passion Diesel
    Nellie - 2014 Mitsubishi Outlander

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