If Tioga Pass through the Yosemite highlands is open, go over it to US 395 on the east side of the Sierras, then take 395 north to Carson City. From there it's a fairly long but manageable 4 lane climb on US 50 to Tahoe's south shore.
If it's not, the most direct route is to go west on CA120 to US 99 and take that north to Sacramento. CA 140 is an easier drive but longer. In Sacramento, US 50 is the preferred route into Tahoe.
If you have the time, you could take CA 49 through the heart of gold rush country, just be advised it will be slow going through the gold rush towns and can easily take twice as long as going via the freeway. Do not take CA 49 between Mariposa (CA 140) and CA 120 - you'll be going up and down through several winding, steep switchback grades as you go up and down the foothill ridges.
The rest of the trans-Sierra routes (88 east of Luther Pass, 89 and 108) have long, steep grades and aren't recommended for RVs.