Today I was put in a 26ft straight struck. I'm guessing the biggest you can drive without a cdl and my 1st time in a truck this large. I was backing into a post office dock. The rubber bumper pads on my truck were in line with the dock bumpers but the hitch on my rental touched the concrete wall. I believe the wall was already chipped in the area where my hitch landed, I would imagine from other people doing the same thing. I'm still bothered by it though. There was a guy on the dock at the time I think a USPS supervisor or manager. He was doing something on his phone and never even looked at my truck while I was backing in or when I was done backing. I was backing so slow I didn't here any loud bang or anything. I mentioned what happed and he said as long as you don't break the folding dock plate you're fine. The funny thing is I still feel like I did something wrong.