From the Bay Area:

Where 580 East splits by 205 toward I5 North and I5 South
Take 205 - 5 North about 12 miles East on Hwy 205
Merge into 5 north & go to Stockton (about 12 miles)
Take Hwy 4 East and go on about 50 miles into Bear Valley

The tricky part is Hwy 4 around Stockton

in order to keep on 4, interchangeably get 99 - on & off.

Just keep eyes open: watch for signs to stay on Hwy 4.

From Sacramento:

Take Interstate 5 south to Stockton
Take Highway 4 east from Stockton all the way to Bear Valley

Bear Valley is approximately 135 miles from Sacramento

From Stockton:

Take Hwy 4 East and go on about 50 miles into Bear Valley
The tricky part is Hwy 4 around Stockton
in order to keep on 4, interchangeably get 99 - on & off.
Just keep eyes open: watch for signs to stay on Hwy 4.

Bear Valley is about 107 miles from Stockton