and I run them on my LWB about 75psi (never under 60psi). the best setup I've found. NO road noise. heavy mud tread. E load rated.

picked up an inch of lift at the same or better lift.

CHEAP cost. Used at all the local mountain strip mines in SW WV.

 

I would recomend setting them at Rover recomended inflation, + or - 10%. At 75psi your riding on a small area of the tread, probably just the center of the tireand beating your suspension and Rover to death. Rover invested a lot of time and effort to establish inflation for both front and rear axels that best suits ride, handling, gas mileage and most importantly oversteer and understeer. + 10% is for heavier load, stiffer ride and better gas mileage. - 10% for softer rideand better traction. The maximum inflation on the sidewall has nothing to do with the vehicle application. It has everything to do with what the tire is capable of carrying at a given air pressure. At 75 psi that tire is capable of carrying 2,900 lbs. per tire or 11,600 lbs total, way over what your Rover is rated for.

 

So, I have a concern. 10 ply tires are hardly ever recommended for off road us, they run hot, tread wear is not good and at the pressure you are running you will beat yourself to death on a rocky dirt road.
When suggesting tires for a 4 wheeler in the disco's weight range, 8 play rating is more then adequate. I run a 265/75/16, 8 ply rated BFG MT with a true 3 ply sidewall. The ideal air pressure to give good fuel economy and tire wear is 35 to 38 in the fron and 40 to 45 in the rear, anything more is over kil and will cause premature tread wear.