I have exactly the same setup as you with the 255 70 18 Bridgestones. Mine do rub a bit at full lock and I had to hammer over the sharp edge on the lower inside fender so it wouldn't nibble the tire. In 25,000 Kms. it hasn't caused any problem but a 1/4" spacer might be all you need. Actually, I think my wheels are what came from the factory on my 09. They are not Rubicon take offs. They look real good and give maximum ground clearance but in offroad situations where suspension can become compressed under sharp turning they will rub too much IMO. I don't offroad that much so it is fine but if you plan on doing a lot of offroading I would recommend a size smaller. Maybe 255 65 18's? You could put in a 1/4" spacer that would probably give you no rub clearance on level ground but it is a different thing when you hit the boonies.
i am running this exact set up too, except i went with the spidertrax 1.5 spacers, my wheel are off a 2012 sahara with the premium chrome spokes (guy said 65th anniversary wheel) i had to do the pinch weld mod once i added the spacers , but instead of keeping the bridgestone at tires that are so lame lookin which are 255/70/18 im gonna go with a 265/65/18 31.6 tire so ill have a little more clearance but a little wider,, works the same as 265/70/17 which is recommenced by rough country