RE: Grr, ok, so they rub...wierd

[JustaxPHX@aol.com]

>Well, my new 16x7.5, ET35 with 205/55 on there are rubbing under any hard 
>cornering...i guess im just going to have to roll the fender...wish i had 
>known this a while ago or i would have bought some 15x8's....

Well, unless you roll the rear fender lips, they'd have rubbed as well ... as
for your 16x7.5s, let's do some math:

Nominal O.D.: 631.9mm (about 4mm taller than the OEM 205/60-15)
Inset: 130.25mm (OEM 6x15 is 121.2mm)
Outset: 60.25mm  (OEM 6x15 is 31.2mm)

Even though the section width of your new tires is nominally the same as your
old ones, the fact they are mounted on a rim that's 1.5" wider means their
section width has increased approx. .6" or so (typically, it works out to .2"
for each .5" increase in rim width).  As you can see from the numbers above,
roughly 9mm the 38.1mm increase in width has gone toward the inside of the car
and the remaining 29mm to the outside.

With an OEM 8x15 wheel, the numbers would have been 125.6mm and 75.6mm,
respectively, and even though a 215/50-15 would be 35mm shorter (which means
fewer problems clearing the firewall and charcoal canister when the front
wheels are turned), your rubbing would be even worse still due to the
additional 15mm of rim width toward the outside of the car.

In the case of my 8x17s with a 33mm offset, the inset measures 134.6mm and the
outset 68.6mm, which is why I've got enough room to run 235/40-17 tires under
my factory-rolled rear fender lips and not rub anywhere.  Up front, they will
rub the firewall slightly when turned to full lock (there's a small spot,
about 1" in diameter, where the undercoating has been rubbed off) and when
backing up at full lock, the right-side tire will rub slightly on the charcoal
canister but since there is room to move it, I'm not too concerned about that.
(Preliminary calculations and measurements suggest that I might be able to
squeeze a 245/40-17 tire under the fenders with a bit of work but I haven't
analyzed how the required offsets will affect the suspension geometry ...
we'll see.) 

Anyway, the bottom-line is that you probably would have been better off using
a wheel with more offset, say, 38mm or perhaps 40mm ... unfortunately, the
only way to get wheels with custom offsets is to have them custom made, which
usually means buying wheels intended for racing and paying through the nose
for them.  However, some companies do make affordable "racing" wheels that're
rugged enough for normal street use -- Compomotive, for one, and Revolution
for another -- and if you don't have your heart set on a particular style, I
can personally vouch that these work out very well indeed.

>Anyway, how bout grinding away that lip?  Is that an option that anyone 
>has tried?  It would prevent any problems with cracking paint and i 
>wouldnt have to worry about removing any body undercoating...

Having tried this once before on an old 4k, I can confirm that it will work
... however, the odds are that instead of cracking the paint, you will burn it
due to the heat caused bygrinding; also, you'll definitely have to remove the
undercoating before you start grinding since it gets all gummy when it gets
hot and clogs up your grinding wheel.  Of course, you've also got to figure
out some way to dull the sharp edge that's left on the fender or you'll
forever be cutting yourself on it ... all-in-all, I'd recommend that you roll
them instead.

JG