I recently bought a 2006 Signum Design 1.9CDTi.
When I test-drove the Signum, it cruised nice & quietly on a dual-carraigeway. There was some road-noise, but no worse that my old 1999 Vectra.
It now seems that the road I test-drove on was very smooth.
Having since clocked up some miles, I am frustrated by how noisy the Signum can be, depending upon the road surface. On rough road surfaces, even at speeds as low as 40mph, there is a droning noise, seemingly from the back of the car. When I get to 70mph on such roads, the noise is annoyingly loud. I can tell from the change in noise level when the road surface changes: - this is far more noticeable in the Signum than in my old Vectra.
The Signum can be quiet at 70mph if the road surface is smooth, so I think the problem is related entirely to road noise rather than anything relating to wind-noise.
I'm wondering if the problem is just due to the tyres. These are Goodyear Eagle NCT5 215/50 R17 all-round. Has anyone else solved road-noise problems by changing to a different make of tyre? If so, which make of tyre?
I also wondered if the problem is the low profile of the tyres on the Signum. My old 1999 Vectra had 195/65 R15 tyres and I was quite happy with them. Would it be worth trying to get different size wheels for the Signum so that I could fit higher-profile tyres, in the hope that it might reduce the road-noise? (I realise this could affect handling and insurance, but if I can't resolve the noise problem then I'll have to trade the Signum).