Date: Mon, 2 May 2016 08:43:41 -0400
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: Tires! 15" or 14"?
In-Reply-To: <2524ABF4-D623-4D73-A8DC-4453A0DBA2DD@comcast.net>
Content-Type: text/plain; charset="us-ascii"
> I thought that it would be Intuitively Obvious To The
> Most Casual Observer that I was Making Reference
> to SideWall Stiffness, Not Load/Weight Recommendations
> I thought that it would be Intuitively Obvious To The
> Most Casual Observer that I was Making Reference to
> SideWall Stiffness, Not Load/Weight Recommendations,
> but I Apparently Thought Wrong ~ So Again to Be Clear
> For You Ron ~ My Point Was -->> >> As SideWall
> height is Reduced the Need for Stiff SideWalls Also
> Reduces <<
Your initial point regarded, in your words, "the Tire Spec's that they did
to the Vanagon." There is no such thing as Vanagon "tire specs" for
"SideWall Stiffness." In fact there is no such spec in the entire tire
industry. The spec is for load capacity. Load capacity is in turn increased
by increasing sidewall stiffness (all other things being equal). VW did not
lower the load capacity requirements when they moved from 14" to 15" and
then to 16" tires. Therefore they did not lower the spec for "sidewall
stiffness."
Contrary to your assertion, they also did not lower the load capacity when
they moved to lower profile (reduced sidewall height) tires. The stock 14"
Vanagon tire has a 6" sidewall. The stock 16" Eurovan tire has a 5.3"
sidewall. Despite its lower sidewall height, the Eurovan's tire load
capacity requirement actually INCREASED. (The increase itself might be
attributed to the slight increase in curb weight - 750 lbs - but even if
adjusted for that, it roughly stayed the same, it did not decrease.) So no,
reducing the sidewall height does NOT reduce the required tire load
capacity. To your point, it may change how the tire manufacturer gets these
(maybe they would need less "sidewall stiffness," this unquantifiable
parameter you mention, to achieve the same load rating if there is less
sidewall), but even if it did, so what? That's an unmeasurable value that
has no bearing on choosing tires. The only spec that matters (or exists) is
the tire's actual load capacity, which is the bottom line, whether they
achieved it by sidewall height, sidewall stiffness, "modern technology," or
magic.
So to summarize, you can change "SideWall height" and "SideWall Stiffness"
all you want but it doesn't change the VW van's tire load capacity
requirement one bit. If the van called for tires rated at 1600 lbs load
capacity before, and you switch to tires with different rim sizes or
sidewall height, you still need a tire rated at 1600 lbs. (Not according to
me, but according to the only real experts that have ever weighed in on this
- Volkswagen themselves, and the National Highway Safety Administration.)
That is the inconvenient yet incontrovertible fact that some retailers try
so hard to talk around, to justify hawking tires that don't meet those
specs. (And that some Vanagon owners try so hard to talk around to justify
purchasing such tires.)
So if you choose to run tires that VW says are underrated, own that choice.
It's your van and your life, and you can justify it any way that makes you
happy. But no amount of justification will change the fact - not opinion -
that you are running tires that do not meet the safety standards set by the
people who engineered your vehicle.
Again - <http://www.busdepot.com/details/tires/>
Ron Salmon
The Bus Depot, Inc.
www.busdepot.com
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