I think the discount code you're referring to is when purchasing a spare from a company called EZ Spare. If you're buying a full-sized spare from Lucid, there is no discount code. If you do a search for EZ Spare, you should be able to find it or someone will respond to this with the answer. The biggest thing to keep in mind is how you plan to use your spare. With a full size, you can carry in in your trunk and take up most of that space, so your storage options might be limited on a road trip. Or having one on hand at home may allow you to swap if you have a slow leak and can get back home. But the EZ Spare one fits in the lower compartment of the frunk which is great for traveling BUT it is a spare that you will want to replace sooner than later and you can't drive more than 55 mph with it.
I opted for EZ Spare just as a means of being able to get somewhere safer or to a tire place if I'm traveling. This way I'm prepared but I don't have to throw a much larger tire into the trunk and take up all that room for something I may not need.