Best tires and wheel offsets for 1.55" lift?

Hey friends,

I have been scouring the threads here and have been struggling to find the information I am looking for.

I have Bilstein 5100s in the front set to the 4th ring, 1.55" lift because I read it can be harder on everything to go past a 2" lift in the front. In the rear, I have Bilstein 6112s and an Icon RXT leaf package on the 2.65" lift with 600lbs setting. This gave me 4" lift unloaded. I have a constant load of an ARE canopy, self-built drawers, and emergency equipment so the rake isn't too bad. I camp, hunt, work out of town and pull a trailer alot, so I am consistently loading the truck, and then it sits level without air bags. I also do alot of gravel roads, and a fair amount of off roading while working at the farm, hunting, and camping/adventuring. I live in Edmonton, Alberta, Canada, so I deal with lots of snow and ice for half of the year.

After the lift I upsized to a 265/75r16 tire. I was on a budget so I got a cheap tire, but now I am looking at getting a higher quality tire, or two sets to switch between summer and winter. I am leaning towards the Toyo Open Country MT 255/85r16. I want to make sure that with my lift I won't have to do any UCA or CMC mods. I am fine doing some cutting if needed. Is there a range of wheel offsets that I can fit this tire without those mods? Or any other tire recommendations?

Any extra information on regearing to 4.88, as I have been recommended, would also be greatly appreciated. As well as any extra information on if I should, and how I can, set the speedometer to the bigger tires would be great!

As a side note, can anyone verify that I can not fit a Michey Thompson Baja Boss 255/85r17 without UCA or CMC mods?

Thanks guys!