My trailer tires have a flat spot if the trailer sits for 3 days. It's pretty significant if the boat sites a week but it's no worse after 14 days of sitting than it is 3 months. I know this because I pull my boat forward 3' or so to hook it up to the pickup. My thought on this is with a 3 mile drive across town the tires are massaged back to round before I get on the interstate 80mph, and I am a self coined "autocondriac " a hypochondriac but to vehicles, I am very attentive and sensitive to my machines. Even successfully tuned two motorcycles fuel mapping with just interstate pulls.