Tyre sizes OEM wheels

[pilchardthecat]

So the stock sizes are
225/45/18 and 255/40/18

I have been running slightly wider rears for the last year @ 265/40/18 with stock sizes on the front

Now i need 4 new tyres, i cant decide what to do. I would like to go 235 on the front, and stick with 265 on the rear, but not sure whether to do

235/45/18 and 265/40/18 (just over 1% bigger diameter)
or
235/40/18 and 265/35/18 (just over 2% smaller diameter)

Help!

 

[WLH]

I have been running 235/45-18 front and 265/40-18 rear on my ///M without any issues at all....
This setup has the advantage of correcting to within 1 MPH the speedometer error....