Tires for fuel economy and grip?

I used to have Maaxis buckshot on the back of my prerunner, but we took them off and replaced them with Hankook AT's to improve the fuel economy. I live in the country, so during the winter I've been finding myself spinning in fields and off road when it's wet.

I've almost been stuck several times, which made me wonder about tires. I have two questions:

If I put tires with tread but are the same dimensions as the Hankooks, will fuel economy drop?

And, if so, what kind would you suggest?

 

if you but tires with tread?



put*

 

I have Nitto terra grapplers. i have them in load rang e. if i was to do it agin i would have got load rang D. they are a little lighter. i have 265/75R16 and i only lost about 1 maybe 2 MPG, I did find the truck handled curves and stuff better than with the P rated BFG rugged trails. I have great on road traction dry or wet and do good off road.

Also the BFG all terrain is a good tire that should not effect MPG to much.

edit: i think the terra grapplers come in P=passenger, but could be wrong. if you don’t go a lot of stuff with rocks, or tow a hole lot P rated tires should be fine. i wanted/need a stiffer / harder side wall for towing and hauling and of roading.