On an RV Forum I saw some posts about tire failures:
There were some posts that mentioned the RV total weight capacity or Gross Vehicle Weight Rating (GVWR). Others were mentioning the total of the Tow vehicle plus the RV Trailer or Gross Combined Weight Rating (GCWR). While others were talking about tire load capacity.
One person responded with: "You need to pay more attention to just what
acronyms are telling you. GCWR has nothing to do with tire inflation
pressures. The tow vehicle and towed vehicle are individual vehicles and
answer to their own standards and regulations.
Maybe you should ask Roger why, during his working years with tires, the
interplay sheer problem was never corrected. (Interjecting a fear
factor for attention purposes might be Roger's goal).
Tire tread separations are a fact that trailer haulers must respect. Fooling
around with RV trailer tire inflation pressures by using less than what
the vehicle manufacturer has recommended is, IMO, counter
Since I was mentioned if the forum post along with the suggestion I might be spreading fear, I felt the need to reply.
Sorry, but Fear is not
and never has been my intent. I covered interply shear and how I
discovered that it was different for multi-axle trailers than it is in
motor vehicles in my blog post of Nov 20, 2013 when I did the first of
multiple posts in Interply Shear as it pertains to multi-axle trailers.
The fact is that Interply Shear is well known in the tire industry but
not the unique forces imparted on multi axle trailers. It was pure
chance that I noticed the irregular path taken by a trailer doing a 180°
U turn on freshly smoothed gravel (picture in the Feb 22 2018 post).
That was my Ah-Ha moment.
While I was retired by the time I first saw
the gravel path, I still had friends that worked with the high power
Finite Element and vehicle simulation software and called in a couple
favors. I asked them to run a simulation of a truck pulling a tandem
axle trailer through a series of "S" curves. All 8 tires were identical
with the same load and inflation so we could end up with a comparison of
trailer effects on tire belts vs the normal interply forces found in
all radial tires in motor vehicles applications. What we discovered
after the overnight computer run, was that in simply S turns (similar to
seen in the video) the belts on a multi axle trailer were developing 24%
higher internal shear forces than the tires on the truck pulling the
This goes a long way in explaining why tires in
multi-axle application have much shorter life and significantly higher
failure rate than do tires in car or truck applications.
you see, Science and facts can be used to point out why blindly
following 50 year old design decisions and regulations that are the
foundation for the current ST tire regulations can be significantly
Post a Comment
Thanks for your comment. We look at each one before posting to keep away the spammers.