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Snow Tires - help, please

Discussion in 'Other Off Topic Forum' started by Doody, Nov 7, 2003.

  1. Doody

    Doody F1 Veteran

    Nov 16, 2001
    6,099
    MA USA
    Full Name:
    Mr. Doody
    okay, i've lived in new england for, well, let's just say more decades than i'd care to mention; and i've never owned a set of snow tires, believe it or not.

    but i want to put snows on the S55. i'm a tad confused and assume there might be others here way more educated in these matters than i.

    the stock setup is 18" tires, 245/45 up front and 265/40 rear. i know enough to know those are NOT common snow tire sizes :).

    MB reccomends you buy new rear rims and go 245/45 all around. of course, they made that reccomendation when nobody made 265 snow tires. now somebody does (Bridgestone Blizzak LM-22 and Pirelli Winter 240 SnowSports - according to tirearck).

    so i have three options:

    (1) get a set of 245 rims and get the 245/45s all around. the most expensive option. this is what mb and tirerack suggest.

    (2) get a set of 245/45s all around and put the rears on the stock 265 rims. tirerack suggested this was doable, though it sounds like a bad idea to me.

    (3) get a pair of 245/45s for the front and a pair of 265/35s for the rear.

    #3 seems like the most rational alternative, with the caveat that the sidewall is 5mm shorter than the stock 40. what i would like to know is, how big a deal is this 5mm rear difference?

    the "airmatic" suspension has three user-selectable modes: regular, middle, and high where the latter two represent, each, a 10mm increase in ride height at standstill (the suspension lowers gradually with speed). so putting 35s on the rear and running the car at "middle" suspension mode results in, generally, the same height as running 45s on the rear - 5mm larger sidewalls than the stock 40 rears.

    any advice out there? with mbworld.org down for over a week now, i can't find a good source of help on this.

    tia,
    doody.
     
  2. bumboola

    bumboola Formula Junior

    Mar 7, 2003
    625
    Doody,

    In Michigan, it would be a death wish to your rear rims if you ran 35's in the back. A friend of mine bent two rims in two weeks last winter before he switched to a different setup with 45's all around. I don't know what condition the roads are in your area in the winter, but I would not run anything less than 45's all around. Also, remember that winter tires have softer sidewalls and "give" a lot more over potholes.

    You paid six figures for a beautiful car, invest in a set of winter wheels and tires for it. It is much easier to change over in the fall and spring and you won't risk damage to your summer wheels from installers switching tires twice a year.

    Paul
     
  3. JOEV

    JOEV F1 Rookie

    Aug 6, 2003
    2,657
    London, ON, Canada
    Full Name:
    Joe
    Doody,

    1) forget option 2. Sure it's possible, but don't risk it.

    2) Blizzaks are awesome snow tires. Other good ones are the European brands that Volvo recommends, Hakkapeliitta or Gislaved NordFrost (maybe check if they have the size you want). I learned long ago that the money for four good snows and rims is money well spent. It's nice to not panic and/or do 360s in a storm like all the people that stuck with their all seasons for the winter.

    3) 245/45/18 vs. 265/35/18

    25.4 mm = 1 inch, e.g. 18" rim = 457.2 mm

    245/45/18 = 245x.45x2=220.5 + 457.2 = 677.7, which = 26.68 inches
    265/35/18 = 265x.35x2=185.5 + 457.2 = 642.7, which = 25.30 inches
    265/40/18 = 26.35 inches

    So how big a deal is the difference? I was told that in order to keep ABS and speedo properly calibrated, you should be within 3% of OEM spec.

    I think option 1 is the way to go.
     
  4. bumboola

    bumboola Formula Junior

    Mar 7, 2003
    625
    Forgot to mention- make SURE you get a set of rubber winter mats for the car. Your carpets will thank you.

    Paul
     
  5. Doody

    Doody F1 Veteran

    Nov 16, 2001
    6,099
    MA USA
    Full Name:
    Mr. Doody
    great info, guys. many thanks!

    i wasn't aware that snow tires had softer sidewalls. hadn't even thought of the potential rim damage issue.

    okay, option 1 it is.

    thanks!

    doody.

    ps: already have the winter rubber mats front and back --- yup, it gets damn messy! and the little monsters don't help!
     

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