I have had the same problem my self. This is my post made in April 08'...
I have a 07 2020 ordered new at the New Orleans boat show in Feb 07. I picked up the boat in April 07 at cypress cove in Slidell, LA. Since this time, 1 year ago, I am currently on my third trailer axle on the starline single axle trailer. The tires are wearing out on the inside from the edge about 3/4'' in to a real worn state while the rest of the tire looks to be wearing normally. I first made cypress cove aware of this problem in August 07. I brought the boat in and starline came and changed the axle for the first time, replacing the axle, bearings wheels, tires. They changed the whole thing. Then around the end of november 07 I noticed the wearing of the tires to be the same. So I contacted Starline directly. The owner, Don Gilbert, sent 2 employees to my home in Louisiana and had them change the whole axle setup again in my drive way this past January. (Great Service huh?) This time upgrading from a 3500 lb axle to a 3750 lb. Now already only 3 months and maybe 1000 miles later the wearing of the tires is the same. Well I contacted Don at Starline again to make him aware the problem wasn't fixed. He asked if I can have the whole rig weighed and get back with him. I went to a truck weighing station and the rig loaded on the trailer weighed 3600 lbs. A little more than I thought it would be. So I let him know and he wants to send me new wheels with radial tires and see if this solves the problem. When I asked him what blazer said about the problem he said that they said the rig shouldn't weigh that much. I'm still uncertain what I should do in this situation. Is anyone else experiencing this problem? I will post pics of the current tires that are only 3 months old and have maybe 1000 miles on them in a day or two. Just looking for a little feed back and some suggestions on how I should pursue this problem and who it should be pursued with? (Blazer, Starline, Cypress Cove?) Thanks a bunch! I just located this forum and I am looking forward to being a very active member!
From here I got Don Gilbert (owner of Starline) to agree to provide me a brand new (free of charge) 5'' I-beam tandem axle trailer. The only thing I paid for was the upgraded 5 star aluminum wheels w/ radial tires (cost me $450). I drove Starline Trailers in Pace, FL one sat morning in May 08' and they made the trailer swap in about 20 min and I haven't had a problem since. I hope this helps.
2007 Blazer Bay 2020
2007 Yamaha 200Z HPDI