Date:         Wed, 9 Mar 2011 11:52:13 -0500
Reply-To:     The Bus Depot <vanagon@BUSDEPOT.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         The Bus Depot <vanagon@BUSDEPOT.COM>
Subject:      Re: And now - still trying for NEW TIRES
In-Reply-To:  <20110309012339.1CB03A007D@locke.alientech.net>
Content-Type: text/plain; charset="US-ASCII"

> Maximum load != normal load. Do you always drive your Vanagon
> loaded to full weight capacity? The regulations certainly
> don't expect that to be the case, and that's not what they apply to.


Exactly. What the D.O.T. is saying is that there should be a safety margin -
that "maximum load" means just that, maximum, not typical. They are saying
that while the vehicle can be driven periodically with the maximum load that
the tire can handle (if it is an LT rated tire - otherwise 9% below), on an
ongoing basis its NORMAL load should be at least 6% BELOW the tire's rated
capacity. This is in addition to, not instead of, meeting the maximum load
requirement. In other words, even if the vehicle's "normal" load is 6% below
the tire's maximum capacity, its potential loaded weight (based on rated
GWVR) must also be lower than the tire's maximum capacity. Both criteria
must be met, not just one or the other. They define normal load as having no
more than 2 passengers, no luggage or cargo to speak of, and no accessories
that add weight. Somewhere I have even seen a spec on what percentage of
time they think a tire should be safely used at or near its maximum load,
but I don't feel like spending hours looking for it.

Bear in mind that VW Campers were sold by Volkswagen as "unfinished
vehicles" and the GWVR is based on that designation. That is why a Westy and
a Non-Westy have the same rated GWVR.  So a Westy will NEVER operate at
"normal load" - rather, it approaches "fully laden" at all times. Your
entire camper interior, the propane and water tank, and everything you have
in the cabinets and under the seats are over and above the "normal load." A
Syncro also has a higher GWVR, even if it is not a Westy.

In theory, it can be argued that the bare minimum tire requirement could be
lower on a 2WD non-camper than on a camper, if it is almost always driven
with no more than 2 passengers and no cargo to speak of.  But even at the
absolute bare minimum permitted by law - an unladen NON-Syncro NON-Camper
with no safety margin at all, not even the recommended 6% - at 1433 lbs
required per rear tire you still need a load index of 97 on any tire that
not does not specifically say LT on the sidewall, or 93 on a tire that does.
The slightly higher numbers on my website (99 and 95 respectively) allow for
the D.O.T.'s 6% safety margin on a passenger van, or for use on a Westy. (If
I were going to really break it down specifically, a Syncro should be
slightly higher still.)

So even if we substitute a slightly lower number for unladen non-Syncro
non-Westies, does that change anything?  No, not really - because in the
real world there are virtually no tires that meet these lower numbers but
wouldn't have met the slightly higher ones anyway. I have never seen a 93
load index LT tire, for example. Virtually all LT tires far exceed that
capacity, and are therefore suitable in that regard for ANY Vanagon,
including Syncros and Westies. Conversely, most standard passenger car tires
have load indexes below 97 (including, incidentally, the Michelin HydroEdge
that GoWesty pushes), making them UNSUITABLE for any Vanagon, even an
unladen non-Westy.  A notable exception is XL (Extra-Load) rated passenger
car tires, which are more akin to LT tires and typically exceed the specs by
enough margin that they're fine for Westies and Syncros as well. The oddball
is the 14" General Altimax XL, which barely squeaks by if you have a
non-Westy non-Syncro passenger van, exceeding the legal minimum by just 71
lbs with no additional 6% margin. (That said, I would recommend reading up
on this tire on the Samba.)

This is all based on verifiable published data, not opinions.  You can look
it up yourself.  If you want to split hairs, argue that your opinion is more
valid than the D.O.T.'s, and/or ignore the safety standards entirely, that's
entirely up to you, and it has certainly been done ad nauseum on this list.
I'm only stating what the published data says.

- Ron Salmon
  The Bus Depot, Inc.
  www.busdepot.com
  (215)  234-VWVW

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