on a long drive would you go bigger tyre or smaller?

I have 235 85 16's on at the moment but am thinking about some 205 80 16's for a more standard look. Now with the change of about 3 inches in diameter between the 2 that must effect the gearing. So on a long (road) drive would you go bigger or smaller? Bigger should cruise faste but have less control and more likely to need to change down up hill smaller oposite right? Any one have experience with different sizes?

depends on enj
Petrol a good one bigger defo 750 or slightly bigger diesel any pre turbo smaller tyres not enough oomph to keep going

Tractor ones on the back, pushchair ones on the front.