Date: Tue, 15 Sep 2009 10:27:31 +1200
Reply-To: Andrew Grebneff <goose1047@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Andrew Grebneff <goose1047@GMAIL.COM>
Subject: Re: Wheel alternative failure?..
In-Reply-To: <1208.65.190.61.61.1252949660.squirrel@webmail.northstate.net>
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> On Mon, September 14, 2009 9:18 am, Dave Mcneely wrote:
>> Didn't see anything on the page supporting using non-stock wheels as a
>> "good idea" (meaning, I assume, that there is something functional that
>> the switch makes work better). I did see that some of the "recommended"
>> tires do not have the load capacity that VW specifies. Load index of 95
>> is simply less than specs. Until I see objective data that support that
>> putting modified wheels (bored to fit, installed with spacers, alloy
>> rather than steel (steel stands up to the stress of back roads better)
>> improves the safety of the vehicle, I remain skeptical. I believe it is
>> a matter of "fashion," and a propensity to keep tinkering, rather than
>> an actual improvement.
Firstly, using "alloy" to describe any wheel not made of steel isn't
incorrect, but is at the same time misleading. ALL car wheels are
alloy... steel is an alloy of iron. Mag wheels are magnesium alloy,
and to be avoided at all costs on road cars (they develop
microfractures which corrode, and can fly apart... check out the
Speedline mags on Ducati Darmahs, which did this). Aluminum wheels
are, of course, aluminum alloys.
The strongest wheels will be steel. They won't break even is serious
accidents, though of course they can bend. But they are ususlly ugly
and will rust.
Cast aluminum wheels are extremely strong also, but can break if
severely abused (eg run across a curb at speed). They can also bend.
Forged aluminum wheels are somewhat stronger, but niot sufficiently so
to be meaningful (we are assuming here that all the wheels we're
talking about are of good quality).
Machining an aluminum wheel to take larger studs doesn't reduce the
strength of the centers... the amount of metal removed in minuscule.
Any other machining eg to clear calipers can be a very different
story; likewise redrilling for a different studpattern. Which is why,
when I wanted 18" wheels to fit over my Porsche 993 brakes, I had the
carriers done in a common generic studpattern, making choice of
unaltered wheels easy... and large.
Machining the center hole should not weaken the center. And for our
vans the center bore isn't load-carrying anyway, so it's only a
problem if you want to sell the wheels later, as most cars center
bores ARE load-carrying.
Adaptors can stress the studs if they're too thick and the studs too
long (if much of the length of the stud is unsupported laterally), and
can also put a torque on the wheelbearings. However you don't
generally hear of failures... and of course car manufacturers can
design-in torques on wheelbearings which cause them to fail (look at
Subaru's Alcyone SVX, which is notorious for wheelbearing failures as
well as transmission & brake failures).
Big aluminum wheels with low-profile tires actually generally increase
the unsprung mass. But low-profile performance tires give a huge
increase in grip tio even a crappy-handling vehicle, and thereby give
a giant increase in safety for those "OH-SHIT" moments where you have
to avoid something suddenly in your way... or try to. I keep saying
it, but few seem to listen... I have experienced the differences
between cheap and not-expensive 14" tires, and this can be a real
eye-opener. The right tires may well save your life... and you may
never even realize it if you have the better tires.
Most of us who own vans will never load them to the point where car
tires will be overloaded, and af course car (including performance)
tires are available for cars as heavy as a loaded T3 (DON'T ask me for
specifics, please, but look at tires for the likes of a Mercedes
S-Class or performance Bentley, for instance).
--
Regards
Andrew Grebneff
Dunedin, New Zealand
Fossil preparator
Mollusc, Toyota & VW van fanatic
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