[A/S] tire wear strange

["argosy1976" <turner.barry@xxxxxxxxxxxxxxx>]

Hi fellow members,

I recently came back from a trip to Yellowstone that had to be
shortened due to tire wear pattern occurring on my 28' Argosy.  The
outside edges of all tires are wearing in an intermittent fashion and
will wear in a cupping shape 3-4 inches in length per cup on the
outside one or two rows of tread and will progress inward toward the
center tread in a 45 degree diagonal.  This has cought me by surprise
as I had not noticed this pattern forming before and one tire had
gotten so worn throughout this trip I decided to replace it.  the
replacement was not very suitable as I had found out later looking at
this site but I had bought a replacement similiar to what was on the
trailer.  This replacement had not shown any obvious wear as the old
tire did over its 1800 Km journey home( the new tire nibs are not even
worn off yet on the outside edge where the old tire had shown its most
amount of wear)below is a before and after and contributing factors list.

contibuting factors:
1) the trialer was hobby horsing as I went over larger bumps in the
road . I concluded the rear shocks in my truck must be almost totally
worn out.(pulling unit is 95 Dodge 1 ton ext cab)
2) the trailer tire pressure was short by 12 lbs. due to a tire guage
that I was using was off by this much(high quality 10 yr old guage).
Ishecked this guage with a tire shop in Yellowstone and I was reading
high by four pounds so thought I was in the right ball park.  I
checked it again later against two other manufacturers tire guages and
the two were identical and found mine to read high by 12 lbs. at a
measurement of 40lbs actual pressure.  Therefore the tires were low. 
This low pressure caused trailer sway around corners. which went down
considerably after the tires were at the correct pressure.
3) I personnally feel that the twin trojan batteries I have mounted in
the rear on the trailer need to be moved to a spot near the axles to
help prevent hobby horsing and side sway - no??


before trip: 
1) no obvious abnormal wear in the tire tread pattern.
2) lots of tread depth left on the tire as this trailer had been a
local traveler and no long trips
3) even wear on all tires( i assumed) and did not see any cause for
concern.
 
during trip:
1) wear developing on the outside row of tread and cupping in toward
the center in intermittent spots on the tire diameter.half the tire
would be normal wear then a cupping wear and some cracking occuring
between the tire tread in the cupping area as these tires are old
enough to show cracking in the stressed areas of the tire (some areas
of the tread and some on parts of the sidewall.  the tires are
goodyear  custom 235/75/r15 4 ply in the tread and 2 in the side wall
with a weight rating of 2100 lbs.cupping wear continued on one tire to
go all the way down to the wear indicator marks on the tread.  this
tire i replaced with another 235/75/r15 of a different make.
2)  used the new tire to get home on and travelled about 1800 km back
home. The new tire still has the tire nibs on the tread surface and
shows no sign of wear.
3) I took a shock off the tire that wore the most and checked it and
it had about a third the amount the resistance that a new automotive
application shock has.  I understand that this shock cannot be
replaced by anything other than a airstream issue shock manufactured
by gabriel.
4) the truck tires are wearing fine.
5) stopped at my third tire shop half way home and got more advice and
found out that my tire guage was off and the other tire shops guage
was off too by 7 to 8 lbs. 
6) one tire shop said the tire was wearing due to shocks and that the
tires would be fine with new shocks installed.
7) second tire shop said the tire belt had shifted and that I needed a
new tire = which i bought.

after trip :
1) no obvious wear in the new tires tread area in fact the nibs are
still on in the tread area.
2) the other tires have slowed thier wear rate after adding the air to
the correct pressure.

IF THIS IS DUE TO A FAULTY AIR GUAGE AND A TIRE SHOPS FUALTY AIR GUAGE
AND MY TRUCK SHOCKS I WOULD LIKE TO FIRST KICK MYSELF.  

Another downturn in my trip:
1) my converter stopped transfering power to the trailer batteries to
charge them.  Neither 110v nor 12v will make it to the batteries.  
2) water line leak in the bedroom due to previous owner not draining
lines well enough for storage.( some how the waterpump wasn't shutting
off and I began seeing my dry bed turn into a waterbed.  I fixed it.


Tell me what is going on with the tires and the converter as I will
take it to a repair shop for an estimate once I know what a new
converter is worth - I seen you all chatting about one such unit in
particular and wanted thier web site.  This converter may not be
salvageable.


thanks for any help!
you may choose to reply to my e mail "turner.barry@sk.sympatico.ca" or
post it for everyone to see.

John Barry