Another 30+ year [loyal] Discount Tire customer here... only once ever did I get a sales pitch similar to that but mine were really worn down and would have been very uneven. I can't even tell you how many flats they have fixed for me for free and with a smile. They are generally the most gracious, timely and put together auto related business. They are kind of like the chic-fil-a of the auto world!
You might relay your experience to that store's manager- it's certainly not the norm for Discount Tire and I'm sure he'd want to know you were made uncomfortable so he could address it.