Boat Trailer Tires Wearing Excessively




 For the average boater, considering the number of miles driven, trailer tires can/should have a long life, if not underinflated or damaged.  However if you happen to be using the newer torsion arm suspension type trailers, as compared to the older axle spring type AND are having excessive wear similar to the tire being underinflated, or excessive wear on either inner or outer corners, READ ON.


 A few years ago I had a friend that had this problem with a King dual axle trailer, he finally drove the boat/trailer to the manufacturer in Seattle and they told him there was nothing wrong with the trailer axles and that they could not repair the axle that he had indicated was going bad.  They said that the problem was that he had the wrong tires on it.   These were factory tires he said, NO they insisted that they always used radial type tires.  His tires were wearing so badly that he was afraid to even drive it home.  OK, they conceded somewhat and sold him new tires and wheels at a slight discount, (of which I bought three of his worn take offs for a small pickup bed trailer I was building at that time).  He then later sold the boat/trailer package a couple of years later.


 Then in 2015, I encountered about the same on my newer torsion arm 2005 EZ Loader single axle trailer.  With three seasons of minimal usage on both these new tires, the tread on the outer 1 1/4" edges was all gone.  And then prior to that, I had also replaced both the tires, moving the one good one to be the spare, because one tire was becoming badly worn then as seen in the upper Left Hand header photo.  And at the time of that photo, I swapped sides so the LH wheel/tire was then on the RH side.  Wear the next year again on the LH side.


 My thought was that with this newer torsion type of suspension, IF/ WHEN the rubber torsion cushions get worn, bad things will happen.  For those that do not understand the torsion system, the trailer axle is square, the spindle has a 90 degree offset rearward about 10".  This unit is made in a double Ell with the forward part of this mounting 90 degrees inward of the extension and the spindle again 90 degrees, but pointing outward.  The inward square part is smaller than the square axle.  Placed permanently between the corners of the inner square are section of rubber placed strategically on all four corners, which allows for the spindle's movement by compressing the rubber, creating an up/down arc centering at the axle.


 My thoughts here is that over time, when these rubbers get worn, then the whole torsion spindle section can move out of alignment of it's original location within the axle, creating havoc with wheel alignment.  In checking, I found a new axle (without bearings) was priced at $599.  In the town I live we have a very good automotive alignment shop.  I stopped and asked if they could help me, YES and the price would be just under $100,  OK schedule me now !!


 After this re-alignment job was finished, I asked the owner what they actually did.  "Straighten the Axle" was the answer.   Well not really, because they actually bent the axle to match the wear in the torsion suspension system.  I guess the term straighten the axle would have sufficed for the average customer, but I being a mechanic/machinist, understood the issue along with their salesmanship, as the axle would in all probability would never have became that bent even by hitting something hard.  The owner of this shop showed me the dimensions they took at the start of the job.  The axle's toe in was -5/8" on one side and +3/16 on the other and with both at a camber vertical angle of +3/32".   None of these dimensions other than the camber were even somewhat close for proper tire alignment/wear.


A brief description of alignment vocabulary may be in order here.    Caster is forward/back angle when viewed from the side and is of little consequence on a trailer, (mostly viable in a steering axle of a vehicle).  Camber is the tilt of the wheels when viewed from front/back, and tilted in/out at top.  Toe in is how much distance when viewed from top, of the tires angled in/out.  There are standard prescribed dimensions for each type of a vehicle.  In my instance, all they actually did was bend my trailer axle to match the prescribed dimensions needed.  If the wheels were not aligned properly, when being towed, rubber is being worn/abated off because one or both tires were drug under a weight of the boat, and at the wrong angle, many times working against each other.


These tires are standard trailer tires, ST 5000, SUPER TRAC, ST205/75D14s sold by Les Swab.  However EZ Loader recommends radial tires ST205/75R1Cs, so maybe the next set of tires I buy, maybe I better look into the radials ??


Here you can see the tread wear, more on the inside, but still considerable on the outside also.  But the outer wear was from the previous year as this tire was swapped sides a year before


 OK, time will tell, and instead of purchasing a set of new tires, I might just try to use it with the existing worn tires for a season, (as I foresee lesser usage because of the wife's medical issues and me being her caregiver) but I will watch them carefully.




Copyright © 2015 - 2017  LeeRoy Wisner  All Rights Reserved


Originated 10-31-2015, Last updated 12-02-2017
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