California hwy 120 between 395 & 6

There's a tunnel on 120 where drops into Yosemite Valley heading West. From the valley to this tunnel has lots of twists, but also lots of turn-outs. The tunnel is an arch roof. Every time I go through it, I straddle the yellow line so as not to loose my AC off the roof as the arch is a lot less clearance on the sides than the center.
Long as you got good brakes, it's not bad.

****EDIT****
Found this;

Big Oak Flat Road

Continuation of Highway 120 from the west into the park

Maximum vehicle length: 45 feet for single vehicle.
Height restrictions: tunnels, from Yosemite Valley: 10 feet 3 inches; into Yosemite Valley, 13 feet 8 inches (the height of the tunnel at the white fogline is higher and California-legal vehicles are able to drive through the tunnel while remaining in their lane).
Seasons: Open all year (chains may be required in winter).

Tips for Pulling a Trailer over Tioga Pass

Highway 120 between Tioga Pass and its junction with US 395 is a steep, winding mountain road. The steepest portion of the road is an eight-mile section that ascends about 2,500 feet (from Lee Vining toward Tioga Pass). Portions of the road have a grade as steep as eight percent.

Other considerations:

1. Adhere to the towing capacity of your vehicle (you might be able to tow a trailer that is heavier than what your vehicle is set up to tow on other roads, but it might not work if you're going up or down this grade); adjust your braking system if you can.

2. Know your driving skills and what you are capable of doing.

3. Many vehicles towing trailers make it up to Tioga Pass (slowly and patiently). However, you may not be able to keep up with other traffic--if you try to, your vehicle may overheat. So, don't try to drive the same speed as other cars that aren't towing vehicles; use the pullouts when you can to allow them to pass you.

4. If you do break down (engine overheating, brakes fail, etc.) be aware that you might be waiting several hours for help (especially if you come through later in the day when fewer people can help you). Have a plan if you break down.