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355 rear tire wear vs geometry

Discussion in 'Technical Q&A' started by ze_shark, Apr 4, 2005.

  1. ze_shark

    ze_shark Formula 3

    Jul 13, 2003
    1,273
    Switzerland (NW)
    DMV inspection coming up, had to put a new pair of Expedias S01 (OEM dimensions) and, like their predecessors, the inside of both rears was completely worn compared to the middle & outside.
    10'000km of spirited driving and a few track days. Not too bad, but I am clearly wasting rubber: a more even wear would have taken these tires a good 2-3K further.
    Searched the archives about 355 wear but only found
    http://www.ferrarichat.com/forum/showthread.php?t=21431
    which links to
    http://ferrarichat.com/forum/showthread.php?t=13258 but all picture attachments were lost in past HD/db crashes.

    Questions:
    - both rear insides worn, both rear outsides good, too much camber ?
    - what is the downside of reducing camber on handling ?
    - other hints or advice before having my geometry checked ?
     
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  3. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    27,086
    Austin TX
    Full Name:
    Brian Crall
    That pattern for rear tire wear on a 355 is normal. The car has quite a bit of negative camber to achieve proper handling. You can reduce the negative camber at the expense of creating understeer.
     
  4. 38 Off

    38 Off Karting

    Nov 4, 2003
    246
    Pace, FL
    Full Name:
    Phil Crain
    Had the same problem. Alignment outfit took as much negative camber OUT as they could by just pulling all the shims (in other words, they moved the camber to as positive a position as possible without modifying the suspension). Wear has been great since, and I have no objection to the handling--really didn't notice a lot of difference. I think if the car was either tracked all the time or you lived in the mountains, the wear might be more even, but doing a lot of highway miles eats the insides bad. Seems like they ran the camber from factory spec of minus 2.3 down to about minus 1.5.
     
  5. yfc

    yfc Karting

    Dec 23, 2003
    212
    Geneva / Switzerland
    Full Name:
    Christophe
    I got the same excessive wear on the inside of the rear tyres. Since my rear tyres are not 100% OEM (265x35x18 instead of 265x40x18) I though that I pinpoint the cause of the problem.

    Thanks to the present thread I now realize that the camber is the real cause of this wear issue.
     
  6. cgperry

    cgperry Formula Junior
    Rossa Subscribed

    Nov 2, 2003
    504
    Chas SC
    Full Name:
    Charles Perry
    I noticed this on my 355 as well and wondered the following. Obviously you can't just switch sides of the tires because they have directional tread patterns.

    However, is there any reason not to have a tire shop dismount both tires and re-mount them in the proper rolling direction on the opposite wheel? Yes, you pay for some extra mounting and balancing, but it seems that you would get longer life out of them as you are wearing the edges more evenly this way.
     
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  8. ze_shark

    ze_shark Formula 3

    Jul 13, 2003
    1,273
    Switzerland (NW)
    Expedias are directional and asymetric, means that they can't be switched sides. The left and the rigth tires are physically different.
     
  9. cgperry

    cgperry Formula Junior
    Rossa Subscribed

    Nov 2, 2003
    504
    Chas SC
    Full Name:
    Charles Perry
    Fair enough. How about for other brands/models where they are directional but not side-specific? Any flaws in my idea?
     

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