If its still got the original Bridgestone Potenzas fitted then the tyre noise is not great.....nor is grip but when they wear out a better tyre makes a huge difference
I'm not sure if you're familiar with the M1 north of Leeds, Mark, but it has been surfaced with something that resembles concrete. It is also evenly uneven, if you know what I mean, kind of wavy instead of flat. The noise is horrendous with any tyre, but as soon as you hit the resurfaced section afterwards, it's like someone has turned your hearing aid off

Considering the list price of these (even base model) astras, I would have thought they would have tried a bit harder with sound insulation and other niceties. I guess they know no one is going to pay full list price, but still........
Mine is shod with Michelin energy, by the way, and they must have been on from new as they have about 5mm left and the car has only done 12000 miles.
Just a thought....I have got 37psi all round in them, maybe I'll drop it a bit.