Sounds like bad timing. You should have changed your residency FIRST then purchased the truck. You could have saved almost 7% in sales tax. To do that legally requires you to have already begun the process of changing your voting registration, bank accounts, driver's licensing etc. If you are simply thinking about registering the rig in SD to avoid paying taxes etc., well that's illegal and you'll be looking over your shoulder all the time. SD does have a wheel tax imposed by various counties. Pennington is one that does not, so look for a MFS in a county that does not...we use Americas Mailbox, but we are full timers...and yes, you have a Class 8 not a Class A....Dennis