I don't know if there is a difference in the RK and the RK Classic pressure recommendations, but here is what my manual says:
Solo Rider up to 150 lbs - 0 psi
Solo Rider 150-200 lbs - 0-10 psi
Solo Rider 200-250 lbs - 5-15 psi
Rider with passenger up to 150 lbs - 10-15 psi
Rider with passenger up to 200 lbs - 20-25 psi
MAX GVWR - 20-35 psi
I am around 200 and with my wife, I usually run mine at 18 lbs.