Discount Tire just lost my business

I had a problem with Wal-Mart.
I have an open trailer that doesn't get much use, so the tire tread looked new,but they were coming apart.
This trailer uses Ford pick -up steel wheels.
Went to buy a cheap set of tires for it & the guy asked me what they were off of, since they were a carry in.
Told him they came off the trailer. He stopped what he was doing & told me that company policy doesn't allow them to install a P series tire on a trailer.
Now this trailer only has 3500LB axles on it.
So be it, I pulled my pants up, cussed a little bit & left.
I did go ahead & install trailer purpose tires on it @ another tire shop.
I do know this, just because you write something down & make a customer sign it, doesn't exempt you from liability.
If the customer is warned & you proceed to do the job halfway, they will come back on you.
I deal with heavy equipment, when I quote it, they either do all of it or none of it.