I can speak from personal experience here. The week after Thanksgiving we excitedly departed on a road trip from central california to seattle. Spirits were high, scenery was amazing. Then at about 10:30pm, on the 101 north of Eureka, in the midst of a heavy downpour we hit a rock that had fallen on the road, and the rear left tire blows out. Pulled over. Used the compressor with the goo, goo spills out the backside of the tire through the very large gash. BMW assist emergency button thingy, no coverage. My friend and I both have AT&T, also no coverage. Friend walks a mile up the road to a call box. He makes several attempts to contact BMW assist, with the help of the dispatcher. After many dropped calls our position is successfully relayed, and help is on the way. Two hours later a flatbed arrives and takes us back to Eureka, and we drop off the car at the smallest BMW dealership I have ever seen. We arrive at Holiday Inn express at 2am. Five days later, worlds smallest but friendliest BMW dealership has finally received and installed replacement tire. My friend flies up to Eureka and brings the car home. Good times.
I'm either getting a donut or a full size front wheel/tire to carry in the trunk for future road trips.