I run 295/70/18 Bridgestone Dueler Revo3's (34.3"). 55 lbs ea vs the 57 lb 275/70/18 Goodyear Duratracs I was previously running (per Tire Rack).
In 10k miles I have noticed no change in MPG or power to the ground going from the Duratracs to the larger Revos. But the Revos are miles and miles better than the Duratracs in every conceivable regard except maybe absolute max off road driving, specifically mud.
I found after extensive searching that, even as an E-rated tire, the Revo3 is the lightest tire in this size on the market, excluding the SL-rated Nitto Terra Grappler. I would've tried the Nittos but the reviews for snow and rain were pretty damning.