? Equal spacing of tires important?

Dr. Feelgood wrote:
Just bought new twin axle TT. When measuring between the tires on each side there is about 3/8 in difference.Some component of the axles,tire mounts or such must be slightly out of parallel.

Your concern shouldn't be whether the tire spacing is different (because it will be) but whether the frame is square and the hangers on each side are mounted correctly to the frame - if so, you have no issues. Spacing between tires will be different AND will vary according to load, where the load is located in the trailer, and ground surface - whether the tires are sitting on a hard flat surface such as tarmac or cement OR are sitting (and sinking into) a soft ground surface such as sand. I myself hadn't given this much thought with the various trailers we owned until I tried to fit a set of adjustable BAL Standard Tire Locking Chocks between each set of adjacent tires on our most recent dual axle trailer and found that sometimes they'd fit, other times not. Of the two sides the chock even when fully retracted to it's shortest length would most often most likely fit between the street side tires but not the curb side tires, the reason I later realized being that the weight of the slide on the street side would cause the suspension on that side to sit slightly lower, forcing the tires to spread slightly further apart than the curb side tires. Once I realized what was happening I further comfirmed by string measure that the frame indeed was square and all the spring hangers were mounted exactly where they should be. My bet is yours is exactly the same and you in fact have no issue. Much ado about nothing.