Yeah well, runflats CAN take you another 30 miles but it's not recommended by the tyre companies. If you're passing a massive shootout and you pop a tyre, then yes, keep driving, but if you pop one on a busy motorway it's best to still put it on the side of the road and wait. All the runflats do is make sure the rubber doesn't come off the rim. Actually driving your car on an empty runflat for 50 miles isn't good for your rims, your suspension, not to mention alignment, since the air isnt there anymore to take the weight of the car. There's only so much a strip of steel can do for you.