Date:         Wed, 3 Nov 2004 21:32:07 +1300
Reply-To:     Andrew Grebneff <andrew.grebneff@STONEBOW.OTAGO.AC.NZ>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Andrew Grebneff <andrew.grebneff@STONEBOW.OTAGO.AC.NZ>
Subject:      Re: Largest diameter... tire failures
In-Reply-To:  <6C902A5A-2CD0-11D9-A0BE-000A95ABA42A@pottsfamily.ca>
Content-type: text/plain; format=flowed; charset=us-ascii

>>Put it this way... the lower the profile/larger the wheel diameter
>>you can afford, the better the handling will be... and as I keep
>>saying, the difference could well save your life in an emergency
>>avoidance situation.
>
>Only if all other factors are equal.
>
>VW designed the bus and Vanagon suspension and steering for a
>specific wheel offset. They also included a spec on tire pressure,
>load rating and sidewall rating. Following these guidelines will NOT
>make a vanagon unsafe, if it did then DOT's worldwide would have
>intervened decades ago. Good luck finding a low-profile tire with
>the correct load rating.

LT tires are not optimum for handling. FAR from it. VW designed the
van to a minimum standard. It can be improved upon very easily...
well-enough designed to make that so. Because VW designed it as-is,
this doesn't mean that it is ideal.

>Depending on where and how you drive, these risks are NOT minimal.
>One of my customers has a box-stock BMW 323 with 50-series Michelin
>tires on it that has had to replace 4 tires in three years due to
>pot-hole incidents. And that's with a suspension designed explicitly
>for that tire and wheel combination.

What sort of roads does he have in his area??

>If you run these tires and wheels on a vehicle that wasn't designed
>for them you are increasing risk.

Not at all. Ask the Germans.

>  Period. That doesn't make a vanagon safer in my book.

Better handling and adhesion doesn't mean better safety?

>
>>According to enthusiast (nonVW) magazines, the better of such tires
>>won't cause a degradation of ride comfort (I'll be able to report on
>>this from personal experience once my van's back on the road).
>
>OK, so now we think the non-VW enthusiast mags know more about the
>Vanagon than VW or the DOT.

The DOT knows nothing... it's a bureaucracy, and uninterested.
Genuine enthusiasts WILL know better, especially nonAmerican ones.
Remember, the DOT decided that halogen headlights should be illegal
in the US.

>One more thing....
>Larger wheels and tires DECREASE horsepower. More rotational mass
>leads to more power required to turn those big spinners, and that
>makes for PROVEN lower numbers on the dyno.

I doubt my 18s are much if at all heavier than the stock 14s with
tall tires. More power is not needed to TURN them... it is merely
needed to speed the rotation up ("positive" acceleration).

>My buses are happy on Continental CR-21's. My Dad's Vanagons are
>running well on Kumho 185R14. YMMV.

YDKWYM (you don't know what you're missing)... but then, very few
listees are driving enthusiasts. They may love their vans, but not
driving (where bends are a challenge).

>  >From working several years at a FLAPS that sold tires I can definitely state
>that low pro tires (50 and under) do not belong on heavy vehicles.

Tell that to Mercedes (including Maybach), VW (Bentley &
Lamborghini), BMW... all make HEAVY large fast cars available stock
with low-profile rubber. All cars designed and sold for driving
enthusiasts (and also a lot of pretenders) come stock with
low-profile tires.

>We saw
>many a wheel come in that had to have the rim and all replaced.  This may be
>one of the reasons for the no flat standard going in in europe.  Pot holes
>were the major destroyer of low profile tires.  The reason was very obvious
>when looking at one afterwards.  The pothole damaged the rim and bead seal
>immediately flattening the tire and rendering the rim useless on many after
>that hit.  Don't know if they did make a change on the road hazard insurance
>but there were discussions on dropping it for low pro tires when I left
>them.

So... avoid potholes. And collar your congresscrook to allocate some
of your tax dollars fix the roads...

>The newer tires that will be made to the flat resistant standard will have
>much thicker sidewalls or another internal structure.  This will enable the
>vehicle to still have rubber under the rims when it flats and maintain
>control of a vehicle after a "sudden deflation incident".  The vehicle is
>supposed to be able to go several miles in that state as well.  Here in the
>US they have been refering to it as "run flat" technology.
>
>  Goodyear and michelin both have tires now on the market for this years
>vehicles.  I believe goodyear got the ferrari contract.  These tires aint
>cheap folks.

I am not going to worry about potholes... there are very few of those
in NZ roads, patchy though they are otherwise.I'm far more worried
about my curb-scrubbing habit. I think my 18s will last OK.
--
Andrew Grebneff
Dunedin
New Zealand
Fossil preparator
<andrew.grebneff@stonebow.otago.ac.nz>
Seashell, Macintosh, VW/Toyota van nut