[Shotimes] Tire/rim width

Carl Prochilo gr8sho@prochilo.myserver.org
Fri, 8 Aug 2003 17:44:05 -0400


That's interesting.  I would have thought that the overall proportions of the
tire/wheel package would be maintained assuming that tire width and overall
diameter remained constant.  My son's 95 is running 235/45s on 17x7 inch
wheels with absolutely no problems whatsoever.  I would then surmise that a
16x7 (or x8) inch wheel should be able to handle a 235/50 series tire.  This
assumes a proper offset.
Maybe the issue turns out to be that the taller the sidewall, the more give it
has under hard cornering resulting in the interference.  Then, dialing out
some negative camber induced by the shorter Eibach springs should give you
more room for the tire.  I believe the Eibachs nominally cause -1.0 in the
rear's.

Carl
  ----- Original Message -----
  From: Ron Porter
  To: 'Carl Prochilo' ; Shotimes@autox.team.net
  Sent: Friday, August 08, 2003 5:18 PM
  Subject: RE: [Shotimes] Tire/rim width


  IIRC, there was a long thread about tire sizes and wheel offsets about a
  year ago. I think I remember that 17" wheels have less of an issue with the
  tire hitting the rear strut housing, as the tire sidewall is farther away
  than it is with a 16" wheel.....or something like that!! Anyone recall
this?

  Ron Porter

  -----Original Message-----
  From: shotimes-admin@autox.team.net [mailto:shotimes-admin@autox.team.net]
  On Behalf Of Carl Prochilo
  Sent: Friday, August 08, 2003 4:10 PM
  To: Shotimes@autox.team.net
  Subject: Re: [Shotimes] Tire/rim width


  This is slightly off the thread, but TR's database will also take into
  account
  the type of car when they apply the fitment guide.  It seems that Gen 1 and
  Gen 2 SHOs are lumped together.  So, if you say you want a 16" wheel and go
  to
  tire selection, they only offer the 215/60 size.  They say this is due to
  fitment problems customers have reported to them in the past.  But if you
  ask
  for a 17" wheel they give the 225 width choice.  Go figure.
    ----- Original Message -----
    From: Ron Porter
    To: 'Leigh Smith'
    Cc: Shotimes@autox.team.net
    Sent: Friday, August 08, 2003 3:49 PM
    Subject: RE: [Shotimes] Tire/rim width


    The best source for the tire dimensions, recommended rim widths, and the
    spec rim size are on Tire Rack's site for virtually every tire they sell.
    Just look under Specs for a given tire.

    Ron Porter

    -----Original Message-----
    From: shotimes-admin@autox.team.net
[mailto:shotimes-admin@autox.team.net]
    On Behalf Of Leigh Smith
    Sent: Friday, August 08, 2003 2:56 PM
    To: dean james
    Cc: Shotimes@autox.team.net
    Subject: Re: [Shotimes] Tire/rim width


    The old thumb rules still hold up pretty well. However there are
    specific manufacturer's recommendations for suggested rim width, for
    each size tire. BFG and Goodyear both do a great job at this and have
    tire info posted on their websites.

    There is another major issue with wide tires on the SHO, wide wheels.
    True a 8 inch wheel would support an 8 in tire ideally. But the tire
    sidewall dimension grows as well. That "thumb rule" is "add 0.5 in. to
    sidewall width for every 1.0 in added to wheel width". This means you
    need to know the "spec rim size" that the mfgr uses to come up with his
    sidewall dimension. It's in the flyers. A 8 in wheel may make the
    sidewall dimension grow as much as 1 inch.

    IIRC, and the reason I bring all this up, is that the major limiting
    factor on tire width on a SHO is sidewall clearance. Mine is 1/2 in.
    (Max) away from the swaybar link "BOLT". with stock size tire/slicers.
    IIRC someone had a stock size tire blow-out at high speed on the race
    track during an earlier Atlanta convention due to rubbing this bolt and
    tearing out the sidewall. There can be a lot of sidewall movement under
    high loads with tall 60 series sidewalls.

    Ian F. has 8 in wheels and 225/55 tires (or /45), but I believe his
    offset is not stock, it is outside a little bit. He has the same bolt
    clearance as stock, but the tire sticks out the fender lip 1/4 in. If he
    were to go to a stock offset to tuck the tire in, he'd tear the sidewall.

    My 0.02 advice, deal with the real threat and sawzall off half the d***
    sway bar link bolt. There is at least another 1/4 - 3/8 in or so til the
    tire rubs the smoother strut. Go with 7-1/2 to 8 wide, and tuck them way
    in with the right rim offset.

    Lee
    "I put 10 in wide wheels inside the stock fenders on a 70 Z28 when
    everyone said it couldn't be done"



    dean james wrote:

    > I had to go out to the parking lot in 100+ degree heat and take some
    > measurements. (109 degrees yesterday!)  Both sets of my Yoko 225's
    > have a tread width of about 7 5/8" which would be 194mm.  So these
    > tires are right at the limit of tread width 1" larger than rim width,
    > and an 8" wide rim should be good.
    >
    >> Equate terms like "the old rule" to "old wives tales".
    >>
    >> If in doubt, go to the Tire Rack Spec site for the particular tire
    >> and size
    >> that you are looking at. That will tell you what the mfr feels is the
    >> best
    >> setup.
    >
    >
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