My experience of Tyeweld = absolute rubbish!
It's not nice for a tyre fitter when they have to change your rubber.. I've had to use it before, it did it's job OK.
I was being told the other day by a cal salesman more new cars are just coming with a can of tire weld rather than a spare wheel 
My daily is one of these cars. Come's with a 12v Leccy pump version.