If you know anything about tyres, you can spot a repair EASILY. A good repair is 100% safe

Also putting a new tyre on is replacing old with new. What I mean is, the tread with be thicker on the new one. So, does every one on hear change all 4 when they get a puncture. Very OTT if you ask me.

Motorcycle. Thats a different thing. I have a 200 bhp bike and ever nail cost me £160. Obviously I only go up to 70mph anyway

And the damage you can't see?

Unlikely with a good budget tyre, and you never drive at 100% initially, giving you opportunity to learn the properties of what has just been fitted.

A tyre in isolation will tell you less about how its been (ab)used than when there's a wheel or preferably the whole car still attached.

30k car? So it's not for your VRS then?

£28,500 with extras. Near enough sarcastic sod