Okay, that was a lot but I will do my best. I put a Zone 6.5 on my 2014 sierra about a month ago so I know what you're feeling. I am running a 17 inch XD wheel underneath with a 0mm offset. From using converters etc..I guess a 5 backspace is the same as 0mm offset. It all kinda confuses me honestly and I was nervous like you are to order online but luckily it all worked out. I don't know anything about the spacers really so I can't help you there. Good luck! Sent from my iPhone using Tapatalk