Not that this has anything to do with you or your decision but...................
My first Toyota had street tread 235/75x15's on it.
I got almost 100miles per mark (4/4, 3/4, 1/2, 1/4, I did) so I thought 400mi exactaly per tank of fuel.
91 Reg. cab 4x4, 5sp, 22r/EFI 180+k.....................
Time came I went to 30" BFG's (from 28"s) becouse I was driving 150mi. M/F and another 300mi weekends. 1,050mi a week total.
Forgot the exact usage per mark, but I wound up loosing exactaly 100mi per tank of fuel overall, and becouse I had steel wheel's I immidietly felt the diference in power.
400mi a tank with 235 (28) streat tread's
300mi a tank with 30" BFG's
Just so were clear BFG's are an excelent tire, heavey, heavey duty, great tread,
3ply, NOT 2ply, 3ply side wall.
INOHIO, the 2" (28" to 31") of over all lift are not worth the stress on the DT, IF they can run the Paris to Dakar, Camel trophies, etc, on those little dough nutz they call tires I dont think the "Tires" got them there....................
The traction did.......ltd. slip........locking axles.........and some Bad ask drivin skills!
I think 235"s are more like 28.5's or 29's cant find the formula ritght off.