First time last week with the D/R. Kept them at 18lbs. all night. My Cutlass with me is 3960lbs. Do you think I should go with more air pressure? 60ft. was kind of inconsistent 1.74-1.77 up and down all night. Do you think I should run more air in them? I know some guys run 20-21 lbs. in some cars. thanks