No mate this isnt the tyre weld foam thats about that you put in when you have a puncture this is a fibrous gel that you squirt the appropriate amount into the valve before you have a puncture and when you drive the centrefreugal force pushes it around the inside of the wheel and coats the inside of the tyre, when you get a puncture the gel gets pushed into the whole via the escaping air pressure and it forms a permenant seal for the legal life of the tyre.
It was apparently designed by the military to bullet proof tires and when 1st introduced to the UK market had to be "diluted" as people were going over police stingers and the wheels were sealing themselves!
I seen this stuff work 1st hand at my local tyre fitters recently, they went and got an old tyre, put this stuff in and then went and got a large pointy screwdriver thingy and proceeded to stab it repeatedly, as soon as the holes appeared they did self seal, i was impressed but have been quoted £60 to have my 4 tyres done, seems a bit steep so i went online and found this webpage, different manufacturer same spec stuff and much cheaper, i quite like the idea of using the F3 grade (ballistic grade) of the product but its apparently not road legal but whos ever gonna tell.....
Just wanted to see if anyones had any experience with this stuff, does it cause any problems such as wheel imbalance?