I wrote the following to my son-in-law about trailer alignment problems. We bought a 2011 used dual axle 30 ft trailer.
I noticed at the barn that the rear tires looked tilted out relative to the front tires. I also noticed that, if you held a straight edge across the tires about midway up that the tires on each side did not touch the straight edge at all four points (left, right, left, right on the cheek of each tire on that side). I wrote an email to Keystone about the patch in the wheel well and a follow-on letter about the tires. They never responded to the later. I also talked to service folks at CamperWorld and they did not appear to be knowledgeable. So, without doing further, we headed out on our trip west.
But, while traveling, it was obvious that the rear axle tires were jutting out at the bottom and the inner tread was wearing away rapidly. I called the axle manufacturer for assistance. They recommended a new axle which I would need to buy through a distributor. I found a place in Ogden UT but the price was over $500 and the delivery would have kept us in Salt Lake for an extra week. (In retrospect, a new axle would not have even been a full solution.)
So, I started checking the rear axle and concluded that it was straight. However, I find that it was supposed to curve upward. If it had an upper curve, the tires would be more vertical -- for some reason -- apparently the spindles and main axles are not manufactured in a straight line. However, I had no way to curve the axle, unless I bought a number of tools. In that process I found a YouTube where these axles are bent (curved) by mechanics to meet tire alignment specs. I then found a place in Salt Lake that specializes in this process and made an appointment. This morning. They checked tire pressures and bearings and then mounted computing machines with lasers on all four wheels and across the trailer tongue. Once they got this setup, the had a pit under the trailer where they (he) mounted a bracket on the rear axle with a hydraulic piston that would bend the axle like bending a bow and arrow (but not so much..). Pump the piston, read the computer. Move the bracket to the far side and do it again. Move the bracket from vertical to horizontal and do it again. This latter adjustment bends the axle (it's round..) with a forward or backward bend, as needed. Go to the center of the axle and do it again. Move all of the hydraulic stuff to the front axle and go through the entire procedure. All of this took 45 minutes and $80 per axle. I got a computer printout of the process before and after. The back tires were each turned out (downward and going forward) in the "before" measurement. The front tires, which I thought were straight, were one turned out, one turned in. The adjustment brought them into horizontal and vertical alignment, ordinarily called camber and toe-in. The owner said that this kind of adjustment was quite common for trailers but not a lot of shops know how to do this. And, it should last for many years assuming you don't do something out of the ordinary. He said, as well, to drive the tires until the steel belts are exposed -- which should be a long time if the tires are in alignment -- even with the aggressive inside wear on the two rear tires. The trailer won't run on that section of tread in the future. And, run them at max inflation of 65 psi -- which I had already done -- trying to preserve the inside tread of the tires -- which is about gone. I might trade the worst tire for the spare, but will watch closely. I actually do not expect to see additional wear any time soon.
So, why the long note. I think the trailer arrived in this condition when we bought it. I think the new tires and wheels were added by the last owner to address tire wear from trips to Myrtle Beach? I also think that the tire might have exploded in Maine because it wore through on the inside where it wouldn't be noticed. And, that your decision to buy additional tires probably resulted from the rapid deterioration of the tires due to this alignment problem.
The new rear tires already look bad after 3000 miles -- if you carefully inspect the inner tread. The outer treads look fine. The front tires look normal. Anyway, I plan to keep using them with the expectation that they will not show additional wear in the future.
BTW - my research says that severe mis-alignment causes both instability and hard pulling. I have been tracking my mileage (about 10) and will let you know if I see some improvement.
P.S. A number of Salt Lake RV dealers told me they send problem trailers (those having alignment issues) to the place we used in Salt Lake.
