New spare, 5 wheel rotation question.

Thanks in advance for any responses.
So, I upgraded my tires to 275's about 12,500 miles ago. A novice tire jockey at Discount tire chipped the "f" out of one of my powder coated OEM ORP wheels. Discount knocked the price off of a new tire by the replacement cost of a new powder coated OEM wheel ($200).
My question is do I need to be concerned about putting the new tire on the back wheel and starting a five wheel rotation with the amount of miles on the current four tires? Discount said it shouldn't be a problem.
Thanks much.

 

Compare the tread depths on your old ones vs the new one. There shouldn't be more than a 3/32" difference. If there is more than 3/32" I wouldn't do the 5 wheel rotation until you get new tires again. If less than 3/32", you should be good to carry out your 5 wheel rotation.