RV route guide
Sonora Pass CA-108 — the Sierra crossing most RVs should avoid
30-foot length limit, 26% grade in places, narrower than Tioga, and a real challenge even in a small rig.
Sonora Pass on CA-108 crosses the Sierra Nevada at 9,624 feet. It is the second-highest pass in California and the most technically challenging Sierra crossing. Caltrans posts a 30-foot vehicle length limit. The grade reaches 26% in places. For RV travelers, Sonora Pass is the route to avoid unless your rig is genuinely small and you are confident with steep mountain driving. Tioga Pass on CA-120, just 50 miles south, is the recommended alternative for every RV class.
- Tier
- Scenic byway
- State
- California
- Best season
- Late June through September. Avoid if your rig is over 30 ft.
- Sources
- Cited official (.gov / .org)
Should I drive Sonora Pass in my RV?
Probably not. Sonora Pass has a 30-foot length limit and 26% grades that most RV travelers should not attempt. The recommended Sierra crossing for RVs is Tioga Pass on CA-120, just 50 miles south. Sonora Pass works only for small rigs (Class B campervans, motorcycles, passenger vehicles) and even then demands experienced mountain driving. Caltrans does not recommend it for trailers.
- 30-ft length limit (Caltrans-enforced)
- Grades up to 26%
- Class B + small Class C only
- Alternative: Tioga Pass CA-120 (50 mi south)
- Open late May to mid-November
At a glance
Route facts worth checking before you roll out
Conservative, source-minded numbers for planning — always confirm against current conditions and state DOT 511 before you depart.
Distance
80 mi
Sonora CA to US-395 at Bridgeport
Drive time
3–5 hr
Elevation
2,000–9,624 ft
RV compatibility
Small RV only (Class B / van)
Max length 30 ft
Best season
Late June through September. Avoid if your rig is over 30 ft.
Cell coverage. Minimal. Sonora and Bridgeport have service. Central pass section does not.
Elevation profile
Climbs from 2,000 ft at Sonora to 9,624 ft at the pass; descends to 6,500 ft at Bridgeport.
Vehicle restrictions
- 30-foot length limit (Caltrans posted)
- Grades up to 26% — the steepest paved highway grade in California
- Tight switchbacks, narrow lane widths
- Trailers strongly discouraged
Real warnings — why we recommend the Tioga alternative
26% grades are real
Caltrans posts 26% in the steepest sections. This is steeper than San Francisco's steepest residential streets.
dangerBrake fade is the practical risk
Sustained steep descent overheats brakes. Use compression braking, not service brakes.
dangerLength limit is enforced
30-ft limit posted. Caltrans cites violators.
cautionTioga Pass is genuinely the better RV option
Just 50 miles south. Gentler grades. No length limit. Use Tioga.
info
What Caltrans + Visit Mono County doesn't tell you
Caltrans posts the 30-ft limit and 26% grade clearly but doesn't always recommend the alternative. For RV travelers, the practical answer is: don't drive Sonora Pass. Use Tioga Pass instead.
The recreational draw of Sonora Pass is the high-Sierra scenery and the historical Sonora Pass Toll Road history. For passenger vehicle and motorcycle travelers it is a stunning drive. For RVs the safer, more enjoyable alternative is Tioga Pass.
Frequently asked questions
- Is the 30-ft limit measured combined?
- Yes. RV plus tow vehicle combined. A 22-ft Class B towing a Jeep exceeds 30 ft combined and does not qualify.
- What if I'm under 30 feet?
- Still expect a challenging crossing. Brake fade is the practical risk. Use lower gears. If you can use Tioga Pass instead, do.
Authoritative sources
Verify current conditions with state DOT 511 systems before departure. RV restrictions may change. Weather may close roads.
Planning an RV trip along Sonora Pass CA-108?
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