33x10.5x15 vs. 285/75/16 gas milage

I've been debating weather or not to stick with my after market alloy 16's and go with 285/76 (or 265) or to go with 33x10.5 and roll on my stock 15's. It's nice that I can get the 33x10.5 cheaper since they're 15's but will it be better on gas milage? I know the tire will still weigh more than stock but since there's not as much surface area against the road, would the 33x10.5 get better gas milage than the 285 or similar? What do you guys who have ran both experienced?

 

if your thinking 285 75 16 its basically a 33 x 11 but i would keep the 15s as a 16 is bigger and can be more heavy depending on the wheels you choose