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Wide tyres

Discussion in 'Bodywork, Tyres, Wheels & Trim' started by sbryantgb, Dec 11, 2012.

  1. sbryantgb

    sbryantgb Senior Member

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    Is it possible to have to much tyre width? The reason behind my question is when I first put 17 inch wheels on my 230ce I had all sorts of steering problems that could not be resolved (the main one being that the cars front wheels wanted to folow every rut and undulation on the road) I finally got rid of this by changing the front tyres to 225's. However I didnt pay attention to the width that came off, and simply put the problem down to bad tyres. However I now have the same issue on the 320ce since having new 245's all round. So is it possible that thats just to much tyre for the vehicle?
     
  2. oigle

    oigle Senior Member

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    Absolutely - 100% correct
     
  3. brandwooddixon

    brandwooddixon Senior Member

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    Yes tyres can be too wide, especially on the front.

    You'll note that generally manufacturers put staggered set-ups on vehicles, with the front tyres being narrower than the rear.

    There are two reasons for this:
    1. Clearance - the wider wheels will rub on bodywork or suspension.
    2. Ease of steering - wider tyres are more difficult to turn and tilt (camber).

    I think that you've found the effects of number 2.
     
  4. OP
    sbryantgb

    sbryantgb Senior Member

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    Thanks for the replies that all makes sense.

    Surely though this problem should be manageable if someone could work out the correct geometry for camber,tracking etc..

    Not that I think that's a viable proposition in this case.
     
  5. kth286

    kth286 Senior Member

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    You cannot go wrong if you follow the AMG spec for the 124s they produced.
     
  6. television

    television Always remembered RIP

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    Often when a car follows all cambers and ruts the tracking is out, and worth have done to preserve the tyre life, and yes the narrower tyres should be better,,,Just out of interest are the 245 standard on a 124, I cannot check for the time being
     
  7. antijam

    antijam Senior Member

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    When I acquired my car it was wearing 18" wheels with 225/40 tyres front and 245/40 rear.

    It 'tramlined' diabolically (and the ride was quite harsh).

    I reverted to standard 16" wheels with 205/55 fronts and 225/50 rears.

    This transformed the car - not only was the ride considerably more supple but the tramlining had completely disappeared and the constant steering corrections a thing of the past.

    Wider than standard tyres - usually coupled with larger wheel size and hence a considerably stiffer sidewall - are an almost certain recipe for poor directional stability. Fine on the track but completely unnecessary for road work (except for the dubious aesthetics!)
     
  8. OP
    sbryantgb

    sbryantgb Senior Member

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    Do you mean for the geometry settings or tyre size?

    I had the tracking etc checked at two seperate places. I don't think 245s are in anyway standard.
     
  9. OP
    sbryantgb

    sbryantgb Senior Member

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    235 is the widest size listed for the front using 17" wheels/the sizing chart on this forum.
     
  10. Bolide

    Bolide Senior Member

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    AMG also specified different springs & dampers so merely using the same tyre sizes is no guarantee everything will be perfect

    If your car was tramlining badly the offset may have been wrong. Normally the offset is chosen to put the centre of the contact patch in line with the centre of the upright. If the contact patch is moved away from there the geometry changes

    The tyre is a spring so any change in dimensions affects the spring rate. Changing a 65-profile 15" tyre for a 45-profile 17" tyre means the spring rate will go up considerably.

    Nick Froome
     
  11. Pathfinder

    Pathfinder Senior Member

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    Simple rule = The tyre should not be wider (overhang) the wheel rim width. If it does, the tyre will flex when driving and make the car wander, especially on the fronts which will be noticeable on the steering.
     
    Last edited: Dec 14, 2012
  12. television

    television Always remembered RIP

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    That is very wrong information, every wheel and tyre in the Mercedes wheel books show the tyre at least 25mm wider than the rim, low profile tyres do not flex much on the sidewalls, indeed if you can detect such movement then you should not be driving on public roads,

    Plus in engineering terms it would make no difference to any flexing if the tyres did sit inside the rims
     
  13. oigle

    oigle Senior Member

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    +1
    Prime example - W163 on 8.5" (212mm) rims is fitted standard with 255mm tyres. I think 235mm tyres are the smallest approved for that rim size and they are still wider than the rim.
     
  14. OP
    sbryantgb

    sbryantgb Senior Member

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    So this issue has nothing to do with the rim or tyre, I guess moving from a 17x7.5 up to a 17x8 is not going to make any difference this issue?
     
  15. oigle

    oigle Senior Member

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    Changing rim size won't fix the issue. It is the tyre tread width that needs to be reduced to reduce tramlining and generally improve steering and ride.
     
  16. OP
    sbryantgb

    sbryantgb Senior Member

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    I had intended to swap the 225/45 from the rear of my other coupe onto the front of this one, and visa versa when I purchased new rims. However having purchased and fitted the rims which are et35 instead of 37 I no longer have this issue. This is quite strange because this pushed the wheels another 2mm further out either side. Which is even further from the standard et42. I can only surmise that something was not quite right with the original wheels. the rear track also increased by going up to 8x17 instead of 7.5x17. Although I don't think that would affect anything.
     

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