Gonna be ordering tires later this year, they'll be used on my just slightly lowered '07 FX4 F-side on factory 20" wheels.

I have looked at several sights, 275/55-20 (oem) is about same diameter as 305/50-20,

I would even consider putting 305s on rear, 275s on front. The overall diameters are closer than a new tire vs old tire so it should work.

Thoughts?

 

Your tires need to match all four corners on a 4x4 or AWD. If not, you'll bust up your driveline.

If it's 4x2, then it doesn't matter if you run staggered tires.

Depending on the truck, a staggered tire setup is neat.

 

since it is an fx4, doesn't that mean it is a 4x4?

 

Yep, it's a 4x4 .... but the tires I'm considering are virtually same OD ... as close as if I just mixed new with well worn .... and if / when I use 4x4, it's slick out or I am in the yard.