Is the car brand-new? If so, it may have been sitting at the dealer's for a while and the tyres might have 'flat-spotted' slightly. This effect will disappear once you've done a few miles.

Check the tyre pressures and make sure they're as per the manual's recommendations.

When we last changed the Octavia was no. 1 on our list but on the test drive in a new demonstrator the noise was literally painful. Dealer said he had never noticed but imediately agreed to get another car for us to try on different tyres, that first was an SE on 195 65 15 Dunlops. The 2nd car an Elegance on 205 55 16 Bridgestones and whilst not perfect was bearable but still noisier than our old C-Max (not a quiet car) thus we walked away.