I am 28/30 with the TKC80 fr and EO7 rear and was the same with TKC FR and RR.
Our "off-road" changes terrain so drastically from rocky, ballbearing gravel on hard pack and then intermixes stretches or full tracts of sand so having a pre-determined "offroad" pressure is difficult. I basically run my on road pressure offroad and if I know its going to get snotty I will drop to 20/20 and maybe 18/18 if predominantly sand.