Date:         Wed, 5 Oct 2005 08:17:10 -0700
Reply-To:     TJ Hannink <tjhannink@YAHOO.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         TJ Hannink <tjhannink@YAHOO.COM>
Subject:      Re: Vanagon Tire Guidelines Report - Are LT Tires really safer?
Comments: To: roadguy@roadhaus.com
In-Reply-To:  <002401c5c9b6$578dd170$50b14e45@t41>
Content-Type: text/plain; charset=iso-8859-1

Larry Chase <roadguy@roadhaus.com> wrote:
> But posting information like this "Out of Context" could lead someone that

> doesn't look at all the data, to misunderstand and make a very unsafe tire

> decision.


Out of Context? Thats why I posted the applicable text on each side of the statement and a link to the original document, so the context of the statement was available.


> To suggest that a Light Truck Tire is more unsafe than a Passenger Car Tire

> when used on a Light Truck is very scary and your clip DOES NOT support that

> conclusion.


Sorry, but thats conclusion that the report writers came up with based on the data they reviewed.



> The clip you posted even states,
>
> "Thus, there may be usage issues that increase the percentage of tire
> problems for these larger trucks, rather than exclusively a qualitative
> difference between P-metric and LT tires.?"


They made that statement in an attempt to explain the data, but they had no data to support that statement, hence the use of the word "may".

They also 'might' have concluded that the heavier light truck tires could cause handling problems at higher speeds and cause accidents but they didn't because they didn't have the data to support that conclusion either even though some would consider that a possible conclusion.



Further down in the article, they get share some of the data on tire failures and both light truck and passenger car tires exhibited failures during their testing. Tire temperature was the contributing factor to the failures of both the light truck and passenger car tires.



> Hopefully most folks can see that this is an apples and oranges report that
> "DOES NOT" reach the conclusion that
> Passenger car tires are a better choice the Light Truck Tires for a Light
> Truck Application.
>
> The other clip you posted at the bottom "Approximately 90 percent of these
> light trucks use passenger car (P-metric) tires."


It looks like the automobile manufacturers have already reached that conclusion if they are willing to stick there neck out and put passenger car tires on 90% of all light trucks.


> If we want to use a passenger car tires, we need to look for the following
> "Minimum" specs.
>
> * XL or RF designation.



How about a 6-ply rated sidewall? The silver sticker in my door jamb has 6PR as part of the 185/14 tire size.

Did the Michelin MXL have the XL or RF designation?


> * Load Range 100



Again, the silver sticker in my door jamb calls for a "97" load rating in the 205/70-14 tire size. That is a passenger car tire since it calls for a re-inforced sidewall and would need to be de-rated by 9%.


> * Max Load Capacity: 1604 lbs (after derated load capacity by 9%)



I don't understand this statement. Federal guidelines call for the combined load rating for the tires on an axle to meet the GAWR of that axle, not exceed it by 10%. (This is also in the article)

Is this 'extra'' safety factor just for Vanagons or does it apply to all VW products?

It certainly doesn't  work this way in the RV and heavy truck tire industry. I have a 13,200 lbs front axle on my RV, the front tires need to be rated at 6,610 lbs each. Air pressure is calculated based on the actual weight of the axle and a load chart for that particular tire size. Any change in tire size or load rating requires a corresponding change in air pressure to support the load - what is written on the silver sticker means nothing at that point.

Since the option tire size for the Vanagon is no longer available, a similar process has to take place using the tire rating info on the silver sticker and the GVWR for the vehicle. If this proceedure is good enough to select tires for 50,000 lb vehicles, it should be fine for a 5,000 lb Vanagon.



I do appreciate the work that you put into the tire selection guide, I just don't agree with some of your conclusions.



Thanks,



TJ Hannink
Goldibox - 1987 Vanagon Camper, Wolfsburg Edition
1981 Bluebird Wanderlodge, FC-33
Winter Park, Florida
http://home.earthlink.net/~tjhannink/
http://groups.yahoo.com/group/wolfsburg_campers
http://groups.yahoo.com/group/FC_wanderlodge
FAVOR website:  http://home.earthlink.net/~clubvanagon

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