TyreWeld, weight saving and pressure at speed

[SlowRider]

Wondering about tyres today ... Is tyreweld any good? Can you still have the puncture fixed or is the tyre dead afterwards. Was going to ditch the spare tyre to save weight, but it didnt feel heavy enough to be worth taking out.

Why do you have to increase tyre pressure for higher speeds? Doesnt seem intuitive to me.

Jeremy