Tyre sealant?

Joe Soap

Having just fitted a carajack to the van, it ocurred to me that prevention wold be better than cure - the cure involving a lot of jacking, and chocking, and generally grovelling around under the van releasing the spare wheel.

I had a look on ebay for tyre sealant - not the kind that is supposed to repair punctures, but the stuff that claims to prevent punctures in the first place.

Anyone used it?, does it work?, and what are the disadvantages (if any)

I'm keen on the idea - but, surely, if preventing punctures and blowouts was as easy as squirting goo into the tyre, everyone would be doing it??