Old tyres are made to last. They are time tested. Like this:
.
You can also brake the rotten floor of your old car and connect yourself with your dear road using your feet if you need that.
I would wonder if daughters appreciate a new set of tyres not installed on a new car.
Is another six to ten years with the old shitbox an encouraging perspective or are they not that smart for their good (they are supposed to obtain a car themselves in that time range)?
Boys should favour girls with new cars, especially if they don't have those!
If the tyres aren't worn out, show no sign of deterioration and you are not looking for a better performance (which is not necessarily the case with newer things
, mind tyres take a run in at least
) I don't think there's a need to replace them. They are pretty simple and sturdy.
Recommendation based on age (well, that age you wouldn't even notice yet) must be a pure marketing here: they want to sell their shit and they expect the fresh to be no harm except for your wallet.
A tyre won't age if you refresh the air in it regularly (a joke).