The alternate to runflat is the new seal technology. Pioneered by Continental tyres, who are the sole supplier to VW for OE ContiSeal tyres, seal tyres have a different approach to ditching the spare. Instead of a hard sidewall that allow you to run safely on the tyre when it’s deflated, the seal technology aims to stop the tyre being deflated in the first place. While the implementation is a little more high-tech than the “can of gunk” you put in bicycle tyres to avoid punctures, the theory is the same. The seal tyres have a 2 part chemical "near solid" compound bonded to the inside of the tyre tread, which when exposed to air in the event of the puncture, instantaneously fills the void and hardens up.