Thanks for the input peeps . Have done a bit of trawling and reckon the "Slime" available at Halfords is maybe a bit of a pretender to the throne , their charts can't really give accurate quantities to use on Bike Tyres and it seems mostly to cater for pushbikes and wheelbarrows etc . The Ultraseal site ( now Puncturesafe ) has a pretty detailed tech and spec section giving specific quantities for a very extensive range of bike wheel sizes , will probably get some of this