My experience with discount codes is that you have to order on the computer and not the phone . The guy on the other end of the line on the phone may not know much and may not even be in the same state as the vendor. The discount code should be alli169 and you need to use your HAMB user name That they will verify.
This discussion regarding Coker came up recently, unsure if Ryan ever clarified it or not. A mod tagged him in the thread.
I have used my Alliance at Coker twice without issue but that was before I started buying round ones from DB. I just went in and looked at the Alliance Vendor list and while their logo is displayed on the right, they are not in the alphabetical list on the left. Unless I messed it. When I bought my DB Auburns I told Bill at DB that Coker gives me a discount, he ponied up with a little somethin somethin.
the last time I bought tires from Coker...they honored the free shipping and gave an alliance discount your experience is more current than mine though...
Here’s the thread I was referring too, but Ryan never clarified. https://www.jalopyjournal.com/forum/threads/coker-tire-discount.1319811/
Actually, Buying from Summit or Jegs is cheaper when they have free shipping than doing direct from the vendor. Just a point to ponder.
I know this doesn't help you, but I've also been much happier with tires I've bought from Diamondback.