I have noted in the latest brochure

 

The SE Estate with 2.0 TDI CR 150PS DPF come with as standard 205/55 R16 91V

 

BUT

 

The Elegance Estate still with the 2.0 TDI CR 150PS DPF  come with as standard 225/45 R17 91W

 

So why such a big difference for the same car and engine?

 

As there is also the £ Difference of some £45 per tyre between the R16 and the R17

 

Both Cars have Tyre Sensors etc so it would seem its just cosmetic - or and depending on the driver either a sporty harder ride on the 17's or a an easier (due to rubbish UK Roads) ride on the 16's 

 

 

I'm not entirely sure what your point is...

 

...but generally, in this country, people think bigger wheels are better.  Hence why the higher spec (i.e. more expensive) Elegance comes with bigger wheels than the SE.  It's got nothing to do with the engine.

Thanks for reading my post

I thought it was all about size and the perceived quality bigger wheels brings.

Just could not work out how the same engine can be fitted with two different wheels

As looking in to it apart from the cost saving the smaller wheel brings you also have a better ride and with premium tyres eg Conti's (but still some £40 cheaper per wheel then the larger) you still have top notch handling.

A friend asked their dealer to remove the 18" as the ride was so harsh

Its as comments on Honest John in The Daily Telegraph, that being, manufacturers get a good deal from the tyre companies to put larger tyres on so tying in the customer to expensive replacements
 

Just could not work out how the same engine can be fitted with two different wheels

 

I'm not entirely sure why you think this.  It's just... odd.

Just could not work out how the same engine can be fitted with two different wheels

you could put 14" and 19" wheels on the same engine, thats irrelevant. The gearing is the same due to the different sizes of tyres fitted.