I ran into that at Costco when buying two tires. They wouldn't put the two new ones on the front. Also had problems with them because my car came with the "high speed" tires (I forget what the code is for them). They wanted to sell me replacement tires with the same rating. I explained that I was an old man and didn't drive that fast and didn't want to pay the extra for those tires. They made me sign some release before they'd sell me the non-speed rated tires.
Mike
Go into the world and do well. But more importantly, go into the world and do good.