Thank you and your answer clarifies what I suspected, putting Slime or similar into a non-run-flat puncture tyre will potentially damage TPMS valve so it will need to be replaced. Hmm, not ideal. Perhaps a small price to pay if it gets you home though. If they did good all season run-flat to fit the 450 it would not be an issue but the choice is very limited with just two summer RF tyres available in the size. A space saver may be a possible. Thanks again 👍