I bought a product called Air-seal this stays in liquid solution within the tube/tyre.Its used on all kinds of cars/vehicles. The litre bottle cost £25 and will treat all 3/4 tyres.
Apologies for prolonging this subject, but I have just been hovering over a bottle in our local stockist. I notice the instructions say that for high-speed road-going vehicles the tyres will need re-balancing after the sealant is applied and the tyres have been initially rotated. Apart from the added cost, with painted wires I am reluctant to let the lads at the local type depot loose on this. I wonder how crucial this is; it probably is, but I wonder if anyone has any views...? A competitor product (OKO sealant) says nothing about re-balancing.