Hi is it not 215/65 tyres it comes with?
anyhow it will gear your car higher (think I got that right way around) means 0-60 slower and top speed higher. Also means your mileometer would show slightly less miles each year as wheel rotation ( circumference )would be bigger but nothing noticeable.
The 165/65 means the profile of your tyre is 65% of the width IE 107.25 mm and at 70% 115.5 mm therefore your profile will be 8.25 mm bigger, your tyre circumference would be 51.84 mm bigger, your speed would actually be 71.86 mph when the speedo reads 70mph.
Miles per gallon would be much the same and comfort much the same, don't know about the AA?
Your allowed a maximum % difference when changing tyres and wheels I can't see what it is but I think its 4% can't remember.
Don't really see the point in going from 165/65 no real benefit.
I could see the point on wanting a bigger rim though to improve the looks but that's another story :thumbs:
Got this info from here, if anyone interested
http://www.carbibles.com/tyre_bible_pg4.html
or
http://www.alloywheels.com/tyrecalc.asp