I put BFG 285 on my 2015 Chevy 2500HD 4x4 DCab- 4:10RE - Stock Rims - NO problems, no rub, rides and look better in my opinion. The install was done at my local Chevy dealer, so he had no issues with the stock rims and 285's...
I took off General 265's - there was some issue with the stock tires, and dealer was changing under warranty. I paid a little extra and had him install the BFG 285's instead. Great fit, no issues highway or back-roads.
Regards the gearing issue -- I do not notice any difference in the power between 265s and 285s, and we haul our camper in the Rockies as well as flatlands ... I also notice MPG similar hauling the camper, but a slight MPG increase when empty on the highway - not enough to matter or even notice, although I have no real world comparison documented.