[trooper Tdiesel]

what kind of rock? theres all sorts of rock roads and they change from season to season..depending on repar of the road, level of traffic, and type of traffic..

is it packed 3/4 minus with fresh layer put on once a year. a common low traffic county road set up..
other then when the fresh rock is spred the amount of added drag on packed 3/4" rock is about as good as it gets for min rolling drag..


or is it the other extreme, raw pit run driving on 4 to 7" rocks.
in that case going around will be faster...then 5/15 mph. and carrying two spares..

don't get siped tires, or pay to have the tire shop put siping on them.
just a little bit of spinning on rock can shred a tire in no time flat...

running rock roads with tires rated at 40psi with 50psi on the car is a bad idea.
there not going to last long.
if they make them, you may want to change the car over to load range C, LT rated tires versus the P rated car ones..
it adds 2 plys to the face of the tire and helps let the tire live a longer life on rock or off road in genral.
LT tires are not common on newer sube's so there may flat out not be a size that fits the auto that's LT rated.

as the truck has much stronger tires load range D or E with a max rating of 65 or 80 psi id run it no less then 45 psi unless your loaded, then up them.