Since you will be in Loomis, the most direct route will be I-80 to Hwy 89 near Truckee. But you will have to climb over Donner summit (about 7200 ft) to do it. No way to avoid the climb over the summit. You could work your way over to hwy 50 by way of Sierra College Blvd/Hazel Ave and then head up 50 over Echo summit, but you will still have a pretty good climb to reach Tahoe. My preferred route would be up 50 over Echo summit which will take you right by the lake and then on to Carson City and beyond on hwy 50. You will have no issues traveling hwy 50.