Originally Posted by OldCoot
So, with ST tires we should never turn table? What are we supposed to do, just tow and back straight and never turn? It was my impression that ST tires were built for the side loads in turning. Guess I was wrong again.
Simplest way to put it OC, the design of STs were originally based on generally lighter use in smaller diameter than where they have reached presently. Manufacturers have only scaled basic design up in large part. Further, the original design wasn't focused on use in multiple axle configurations. I'm sure that retired tire engineer that popped in here, and if still reading the forum, can take it further than I.
The issue is not true side loading that's at issue with turntabling. It's torsion working at the construction not designed for it. Sure, we've all turntabled but let's admit that at least 75% of those times we could have done a multi-point negotiation to get our rig in there... Let me share an experience I had with an old client. He bought a new TT that was 7 feet longer than his prior and was constantly blowing curbside rear tires on the tandem axle. Spent thousands between tires and alignments and even axle replacement before I was asked to look at it. After meeting him at his Houston home I began to see clearly why he was facing this constant problem. In order to negotiate the narrow street and driveway angle with that long trailer and pickup, he was binding the tandems so tightly (ugly too) he was spinning on that tire (on a broomed concrete drive) as it was taking nearly all of the load on that side with the forward axle lifting due to the slope and coupler fixity. He was basically pushing the trailer in place skidding the curbside front too. Worse yet, he was leaving the bind and just unhitching! He didn't realize any of this should be a concern, but anything that puts something in a state of stress other than its at-rest design condition is a concern.
We sent the tires to one of my sponsors at the time to have them cut and examined. Sure enough, this maneuvering was causing the tread to shear away from the carcass. These were 5 month from manufacture, big brand tires with less than 1500 miles on them. The same manufacturer is who cut them and examined.
So, I am in the camp of if your axles look really ugly negotiating backing in, readjust and work it in over forcing it in. YMMV.
He never had a problem with the trailer again after adjusting his backing habits and then moving 1.5 years later out in the countryside where he now has acres, a 5er, and a pole barn for it to sleep in that he can literally pull-through!
As I said before, I'd be willing to pay a premium for a well-engineered and manufactured trailer tire!