Sorry about all the tire trouble. I have been towing trailers for over 60 years and can count my flats on one hand other than one trailer that blew out 9 in one summer. I got rid of that problem by selling the trailer. I have a 99 tri axle that I bought new and have had one tire separate and cut one down on a toll booth curb and it has been towed way over 100,000mi. It has 235-75-15 tires on it from Wal-Mart. 2 things I do that may help you all some. 1-I check the air before I start out and every time I stop and run 40psi of air and 2-I never tow the trailer when it is not level or very close. When the nose is up the back tires are carrying most of the weight and when it is down most of the weight is on the front. Some may not agree but this has worked for me for many years.