Standard prime rib mass 7 lbs Initial Temperature of prime rib Oven Temperature Recommended Rare done prime rib - Temperature at center of the thickest part of the meat 4.5 C 163 C 60 C Density 1200 kg/m 4.1 kJ/kg. C k a 0.45 W/m . C 0.91 x 10-7 m/s