Date: Sun, 31 Oct 2004 15:33:48 -0600
Reply-To: John Rodgers <inua@CHARTER.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: John Rodgers <inua@CHARTER.NET>
Subject: Re: Largest diameter wheel.
In-Reply-To: <41854461.7040207@comcast.net>
Content-Type: text/plain; charset=windows-1252; format=flowed
My experiece as well.
Note that I too drive an 88 Vanagon based vehicle. Only mine is a GL and
therefore lighter in weight than your 88 Westy.
However, my last set of tires before the XCA's were the Michelin MXT's -
also in size 205-70R14. The only difference I have noted between the two
tire types - XCA vs MXT - is that the MXT definitely had a more
agrressive tread. On dry pavement I perceive no difference between the
two tires, but on wet pavement the difference is significant - in favor
of the MXT.
Even so, with the MXT no longer being available, I still would
recommend the XCA, if one wishes to stick to a 14 inch tire. It is a
hell-for-stout tire, having a tall, stiff, sidewall required for our
vehicles - a tire with a true 6 ply sidewall with 8 plys on the road, in
a load range "D". Difficult to match unless you step up to a 15 inch rim.
Regards,
John Rodgers
88 GL Driver
Todd P. Last wrote:
> Good point, as you increase the surface are of the tire, the weight on
> each sq. inch. will be reduced - making it easier to break traction.
> Wider tires also tend to make the contact patch more rectangular
> (shorter front to back) compared to a smaller tire (with the vehicle
> weight constant.).
>
> I have Michelin XCA's as well and agree, they are great dry tires and
> wear like steel. (I have 25K miles on mine and they look virtually brand
> new as far as treadwear.)
> But they are not for wet driving - they slide easily on wet roads
> anytime you make abrupt steering or braking inputs. Interestingly, these
> are no wider than the tires they replaced on my Van (Michelin MXT's) So
> I have to assume that the difference is a combination of the stiffer
> sidewalls, harder rubber compound, and hi-way tread.
>
> Todd
> '88 Westy
>
>
> John Rodgers wrote:
>
>> I cannot address the issue of what size (diameter) rim that can be used,
>> but here is a caution.
>>
>> You do not want a tire on a Vanagon whose road contact surface is really
>> wide. While wide tires may look "Macho", they are crap when the chips
>> are down and you need serious friction on the road for vehicle control.
>> There is a functional relationship between the total surface of the tire
>> in contact with the road, and the amount of weight bearing down on that
>> tire contact surface. If that relationship is upset by changes in either
>> weight or tire contact area, then performance is degraded and may be
>> responsible for an accident of the skidding kind. Generally speaking,
>> and this is "Generally", a wider tire will have have less traction and
>> be more likely to allow the rear of the vehicle to de-stabilize
>> resulting in a skid. Not a good thing most of the time. Although I have
>> had in my driving career at least two occasions where being able to
>> easily induce a skid saved my butt by allowing me to get out of the way.
>> The relatively narrow tire specified for the Vanagons was done so for a
>> reason. Vanagons really are "trucks" by nature, and as such have widely
>> variable weights at different times. A narrow tire with a high load
>> rating at the road will be a more controllable vehicle in varying
>> weather conditions, but most especially in wet weather conditions.
>>
>> Be especially careful about the tread type. I run Michelin XCA's
>> 205-75R14's. I find that in dry weather it is a great tire. But it is a
>> truck tire. And as such it doesn't have a very aggressive tread design.
>> The tire relies on that heavy load ratios of the bigger trucks for the
>> friction it needs for stopping and also to avoid skidding. My vanagon
>> simply doesn't have the weight for the tread type. Consequently I have
>> to be more aware and more careful when driving in wet weather. Don't get
>> me wrong. I love the tire, but it has it's limitations. Less than the
>> best aggressive tread is one of those limitations. In this case, with
>> the loads I carry, the number of grooves in the tire tread is
>> inadequate, consequently the wide rubber between the grooves in the tire
>> tend to make the tire want to float on the film of water on the road
>> when it is raining - hydroplane - So I have to be careful. More weight
>> would force the water out from under the tread. But I don't have more
>> weight. What to do, what to do? Increase the number of grooves in the
>> tread. This allows the narrower rib of the tread to cut through the
>> water, displacing it sideways and into the grooves of the tire,
>> resulting is more rubber on the road. Thus the better control.
>>
>> So it is all a balancing act between rim sized o carry the right, tire,
>> sized for the best contact with the road, adjusted for weather type, and
>> load.
>>
>> We take it all sort of for granted, but rim, tire size, tread type, and
>> loading are really fascinating subjects and important.
>>
>> Again, be careful of what you do with tires when you change them.
>>
>> Regards,
>>
>> John Rodgers
>> 88 GL Driver
>>
>> jimt wrote:
>>
>>> I am just looking for the largest diameter wheel that can fit in the
>>> wheel
>>> well of a 2WD vanagon. And be used of course. Not into adaptors or
>>> anything else just the diameter or tire sizes and I will compute the
>>> diameter.
>>>
>>> Height not treadwidth.
>>> Thanks
>>>
>>> ••••••••••••••••••••••••••••••••••••••••
>>> jimt
>>> Planned insanity is best.
>>> Remember that sanity is optional.
>>> http://www.tactical-bus.info (tech info)
>>> http://www.westydriver.com
>>>
>>>
>>>
>>>
>>
>
>
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