Do the 'economy' tyre pressure settings on my Vauxhall Insignia help with mpg and will they affect tyre wear?

I recently bought a secondhand 2009 Insignia 2.0 CDTI SE to replace my 2001 Toyota Avensis 1.8 VVTI. I hoped to improve fuel economy with my change in car. The Insignia, which is a diesel, has only just bettered this by returning 40.5mpg on my first tank (no motorway runs included yet). I decided to check the tyre pressure and consulted the manual to find the correct settings. I found there was the option of ‘comfort’ or ‘economy’ pressures and decided to try the economy settings. I have yet to empty a second tank to see if there is any measurable improvement (I expect it will only be slight) but I am concerned if the higher pressure could lead to accelerated tyre wear on the middle sections of the tyres. For the record the recommended pressures are: Tyres 225/55 R17: Front 32 psi (comfort), 39 psi (eco); Rear 29 psi (comfort), 38 psi (eco).

Asked on 5 January 2013 by NK, Cottingham

Answered by Honest John
We tested an ecoFLEX version of the Insignia and averaged 55.7mpg on the dashboard meter over 600 miles, but it did feel a bit skittish on its high pressure, low rolling resistance 225/55 R17 Michelin Primacy HP tyres. See:
Similar questions
The accuracy, or otherwise, of manufacturers' fuel consumption figures attracts regular correspondence but my question is slightly different. We have just taken delivery of a new Vauxhall that boasts start/stop...
I purchased a new Mercedes-Benz E220CDI in December 2009. In January I received a call from the dealership asking me to take the car in for a warranty job to be carried out. I took the car in and waited...
Having had three new 195/45R16 tyres fitted to my 1.6 diesel Fiesta I was interested to find that they had all been inflated to a pressure of 37PSI. The car handbook recommends 33 at the front and 26 at...
Related models
Superb ride comfort, excellent efficiency from the diesel engines, practical and spacious.