Once you get to their shop, the folks there will tell you they don't make any commissions on tire sales, yet keep pressuring for an upsell.
That may still be true. When I worked at Lowe’s in collage, they constantly pressured us to sell extended protection plans, because the company made like 87-89% profit margin on these (hint hint, there’s a reason companies sell these extended warranties…).
However, there was no direct benefit to us
to sell them. We didn’t get a bonus if we sold an extended protection plan. Only not getting nagged at if we sold “enough” plans, and getting “praised” if we did sell enough, usually in the form of “cashier X got a 70% EPP close rate, you’re only getting 15%, try harder!”
Luckily I got moved pretty quickly to customer service, and doing returns my profit margins and EPP sell rates were negative, since mostly I just processed returns and didn’t check people out, so I stopped getting bothered about selling them other than an occasional “remember if you process a sale to always offer an EPP.”
I always did, but since I didn’t believe in EPPs myself (they are basically just a profit stream for the company with little benefit to the user), I would only ask “did you want the EPP on that?” When (most) customers said no, I didn’t push them and just declined it and carried on.
I really hated the corporate push for selling EPPs because some cashiers would outright lie to customers on what it covered, how to use it, etc, and then I
had to deal with an annoyed customer when they came in and said “I was told with the EPP I could just bring it back to the store if it failed.” No, with some limited exceptions, the customer was always required to CALL some 1-800 number to get a replacement, or a replacement code FIRST which they could then bring to the store. Hardly anyone did because the cashiers would lie, or not inform the customer of the details of the plan. We were supposed to give them the “fine print” and tell them “if you have an issue, CALL this number.” But few cashiers ever did, and I had to deal with the consequences when people were upset they had been lied to. All because corporate had such a big push on the EPPs, because of the super high profit margin.
Long way of saying that just because something isn’t commissioned based, doesn’t mean the employees aren’t pressured behind the scenes to make the sale of something, and I suspect it’s similar at Discount Tire with the warrant certificates. If I had to guess, they can offer such low prices in general, free tire repairs, etc, because they make it up with Warranty Certificates that they probably make a 70% or higher profit margin on.