Upon purchasing the vehicle new I insisted on 17" rims and that run-flats should not be fitted.
The car arrived with Bridgestone Turanza tyres fitted on 17" rims, great.
On the first day and a few miles away from the dealership where the road test roads are very good I noticed the road noise on our normal roads.
I complained to the dealership, whereupon they road tested the car and found it to be in their words satisfactory.
I asked for the advice of the ''Diesel Car & Eco Car mag'' who suggested a change of tyres to Goodyear Efficient Grip's.
Before I changed the tyres I recorded sound pressure level readings over five specific roads at particular points.
Followed by reading with the new tyres (after 200 miles to remove the new edges) the average reduction was 3.72 dB.
Unfortunately, in reality it takes a reduction of 5dB to make a reasonable noticeable difference for the human ear.
Hence my investigation into acoustic soundproofing, as I love everything else about the car.
Graham the engineer.