Well, you did the right thing by switching all of them. Two different sized tires = bad for awd. Personally I don't carry a spare (and I don't have RFT's). It's a risk, but I really don't want to put a wheel in the trunk. I just pay a little extra on the insurance for good roadside/towing service if this happens to me.
'07 335xi, Alpine White
| Cold, "Sport", and Luxury packages | Tinted | OEM Black Lines | JB4 | DCI | ER FMIC | Forge DV's | Custom exhaust with secondary cat delete, Magnaflow mufflers, black Dimisa Tips | Staggered 18" V718's, Matte Black | Flappy Paddles | Titanium CF Trim Wrap | BMW Performance Shifter and E-Brake Handle |