have any of you tryed running 31/12.50/15 inch tires on 15x10 rims, im going too be getting the calmini lift and steering system, i like the look of a wider stance on my lifted 4wd trucks, and its my daily driver (60 mile commute daily) so im going too stick with 31's too get at least a little fuel economy. so just trying too get an idea if anyone is running a lifted x with that rim and tire setup. thanks in advance for any assistance

You'll have major rubbing and your truck will look like a lifted go-cart, but if you like that kind of thing give it a try.

If you go with 32 x 11.5's on stock rims you'll be a lot happier and there would be very little difference in mileage, if any. Remember, the mileage difference is mostly related to the weight of the tire and the amount of drag it creates from the contact patch. Whether you go wider or taller it's not going to make much difference.