Trying to figure out if running 255/40/17 on the front and 295/35/18 out back would look funny and out of balance(proportion)
The front wheel is .06" taller which I don't think you would notice but I thought having a bigger profile in the front would look odd.
Anybody running this combo ?

It depends on the width of the wheels too. If the rear wheels are a little wider, then your 40/35 profile combo will look ok. I went with 225/40 on an 8" wheel and 275/40 on a 10" wheel for the same reason.