I looked at the Garmin TPMS but there's not enough clearance between the rear tyre and the drivebelt.
They also need a metal valve stem and mine is rubber so would mean refitting the tyre as well.
Alternatively I've also looked at
http://www.puncturesafegu.co.uk/Has anyone tried this?
Yes I have this type of product in my both my rear and front tyres. I used a product called Puncture Safe its been in for over 8000 miles and allegedly will seal tubes as well if the hole is small. It is easy to use just let the air out, unscrew the valve and inject the the recommended amount in the tyre and re inflate and spin the tyre to coat the inside of the tyre, it does not affect the balance.
Does it work ? Don't know as I haven't had a puncture !