6-1/2 x 2 minimum and if a VS super wide then 7 ' wide. Keep in mind that if you use a utility trailer with angle metal sides you need to consider door opening clearance or you'll have to get out with the top down. If the trailer has a one piece fold up rear loading ramp12' will not be long enough even with the car all the way forward on the trailer. BTW I have changed my perspective on X crossing the load straps after seeing the result of someone's strap breaking the remaining three loose their anchor points .