Mountain driving tips for truckers: win the grade at the top
On a long downgrade, the decisions that keep a loaded truck under control are made before the descent: the gear you select at the summit, the speed you commit to, and the condition of your brakes.
Written by Rigo Diaz
Mountain driving in numbers
The mountain driving tips that matter most for a truck come down to the downgrade: check your brakes and route before you go, select a low gear before you start down, let the engine hold your speed, brake in short firm applications, and use a runaway ramp the moment your brakes can't hold you.
Most of a mountain run is ordinary driving. The risk concentrates in a few miles: the top of a long downgrade, where the gear you chose and the heat already in your brakes decide how the rest of the descent goes.
I spent more than six years in risk management before I founded Simplex, and I have led the company for more than 25 years since. This guide is about those few miles: what to do before the climb, how to come down, what to do when the brakes won't hold, and the Colorado rules many of you will run under.
The full briefing, read aloud
8 chapters. Select one to jump to it.
Generated with AI text-to-speech from this article's key insights, in order, rather than reading it word for word. Chapter times come from a transcript of the audio. The article itself was written and reviewed by Rigo Diaz.
Key takeaways
Choose your gear before the top
Once speed builds you may not get into a lower gear at all, and modern trucks often need a lower gear going down than coming up.
Engine first, brakes second
Brake to about 5 mph below your safe speed, release, and repeat. Each application lasts about 3 seconds.
Adjustment decides brake fade
Brakes out of adjustment quit first and the rest overheat. Check function and adjustment before you descend.
Use the ramp, and use it early
Waiting lets the truck gain speed. In Colorado there is no fee, penalty, or fine for using a runaway truck ramp.
A forecast storm doesn't add hours
The 2-hour adverse driving exception only covers conditions you couldn't reasonably have known about before the duty day or dispatch.
In this articleContents
Why is mountain driving harder on a truck?
Because gravity works against a loaded truck in both directions. Climbing, it slows you and forces lower gears. Descending, it keeps adding speed, and your brakes have to turn that energy into heat.
Brakes are built to take a lot of heat, but not unlimited heat. When they get too hot they start to fade: you press harder for the same stopping power, and with continued hard use they can fade until the truck can't slow down or stop at all. The heat changes the lining and expands the drums, so the shoes have to travel farther to reach them.
Adjustment matters as much as technique. Brakes out of adjustment stop doing their share first, which overloads the others until they overheat too. And brakes can drift out of adjustment quickly, especially when they're used hard, which is exactly what a long grade does.
The Colorado Department of Transportation puts it plainly: in a truck up to 70 feet long and 80,000 pounds, mountain terrain increases the likelihood of brake failure, and the state's runaway truck ramps are used most in summer. Hot brakes are not a winter problem.
What should you do before driving in the mountains?
Before driving in the mountains, learn the grades on your route, check the weather and any chain requirements, and confirm your brakes work and are in adjustment. Federal rules already say you can't drive until you're satisfied the service brakes, parking brake, tires, and other listed parts are in good working order (49 CFR 392.7).
- Know the grades. Find out where the long, steep grades are and, if you can, ask drivers who know them what speeds are safe. FMCSA warns that non-commercial navigation apps may not flag truck restrictions.
- Check brakes and adjustment. Do it in the yard and again at the summit before you start down. Our brake inspection checklist covers what an inspector looks at.
- Check weather and chain laws. Mountain weather changes fast. Carry chains where a state requires them, and know where the chain-up and brake check areas are.
- Find the runaway ramps. Signs mark them, and Colorado's COtrip map shows them, but know where they are before you need one.
- Budget the time. A slow climb, a cooling stop, and a chain-up all take time. Plan them into the trip so nobody tries to make it up on the descent.
Does bad weather give you more driving time?
Sometimes. Under 49 CFR 395.1(b), a driver who meets adverse driving conditions and can't safely finish the run within the limits may drive up to 2 more hours, to complete the run or reach a safe place. That stretches both the 11 hours of driving and the 14-hour window.
The catch is the definition. Adverse conditions means snow, ice, fog, or unusual road or traffic conditions that weren't known, and couldn't reasonably be known, before the duty day began or before dispatch. A storm in that morning's forecast doesn't qualify, so plan around it. For the limits themselves, see our guide to fatigue management for truck drivers.
How do you drive a truck down a steep grade?
Choose a safe speed, select a low gear before the top, let the engine do most of the braking, and use the service brakes in short, firm applications. These steps come from the commercial driver's license manual drivers study for the test; we used the Texas edition.
Step 1: Pick a safe speed
Base it on the total weight of the truck and cargo, the length and steepness of the grade, the road, and the weather. Never exceed a posted speed limit or a "Maximum Safe Speed" sign, and watch for signs giving the grade's length and steepness.
Step 2: Select a low gear before the descent
Shift down before you start down. Once speed builds you may not be able to get into a lower gear, or back into any gear, and you lose all engine braking. Forcing an automatic into a lower gear at speed can damage the transmission and cost you engine braking too.
The old rule was to use the same gear going down that you'd need to climb. The manual now warns that modern trucks, with less friction and drag and stronger engines, may need a lower gear going down than going up. Know what holds your truck.
Step 3: Let the engine hold your speed
Engine braking is your main control, and it is strongest near governed rpm in the lower gears. A retarder or engine brake helps, but switch it off on wet, icy, or snow-covered roads: it brakes only the drive wheels and can make them skid. Colorado DOT also advises using your flashers to warn traffic of your reduced speed.
Step 4: Brake in short, firm applications
Once you're in the right gear, apply the brakes hard enough to feel a definite slowdown, release them at about 5 mph below your safe speed, and repeat when you're back up to it. Each application lasts about 3 seconds. With a safe speed of 40 mph, you brake to 35, release, and repeat to the bottom. Riding the brakes all the way down is what cooks them.
Step 5: Cool the brakes when you can
Pull into brake check areas, or onto a safe shoulder. Don't set the parking brakes while the brakes are very hot, because the heat can damage them. Chock the wheels on level ground and let the brakes cool first.
When should you use a runaway truck ramp?
As soon as you know your brakes can't hold the truck. The CDL manual is blunt: if there is a ramp, use it. Waiting only lets the truck gain speed and makes it harder to stop.
Escape ramps use a long bed of loose, soft material, sometimes on an upgrade, to stop a runaway without injuring the people aboard. They are usually a few miles below the top of the downgrade, with signs ahead of them. Colorado DOT's guidance for using one:
- Move into the far right lane before you reach the ramp.
- Steer straight in and keep the wheels aligned.
- Stay in the center of the ramp to avoid rolling over.
- Once stopped, call 911, even if no one is hurt.
In Colorado there is no fee, penalty, or fine for using a ramp, so pride is the only thing stopping a driver. If there's no ramp, take the least hazardous way out, such as an open field or a side road that flattens out or turns uphill, and make the move early.
What are Colorado's mountain driving rules for trucks?
Colorado requires commercial vehicles with a GVWR or GCWR of at least 16,001 pounds, used in commerce or carrying 16 or more passengers, to carry chains or approved traction devices on its main mountain corridors from September 1 to May 31, and to put them on when the chain law is active. The corridors are:
- I-70 west of milepost 259 (Morrison) to the Utah line
- CO 9 from milepost 63 to 97 (Frisco to Fairplay)
- US 40 west of milepost 256 (Empire)
- US 50 west of milepost 225 (Salida)
- US 160 west of milepost 304 (Walsenburg)
- US 285 west of milepost 250 (Morrison)
- US 550 from milepost 0 to 130
When the chain law is on, tractor-trailers and straight trucks need chains or approved devices on four drive tires, or all drive tires if there are fewer than four. Trailers don't need chains. Trucks stay in the right lane except to pass a stalled or slower vehicle without losing traction. Placarded hazmat loads may pass the chain-up signs and chain at a safe spot off the road where the pavement is snow or ice covered.
| Violation | Fine | Surcharge |
|---|---|---|
| Not carrying chains on a listed corridor, Sept 1 to May 31 | $100 | $32 |
| Not chaining up when the chain law is in effect | Up to $500 | $78 |
| Stuck and blocking the road without chains | $1,000 | $156 |
CDOT also names its hot-brake trouble spots on I-70: westbound just east of Silverthorne near exit 205, and eastbound near Georgetown at exit 228. The Lower Straight Creek ramp on westbound I-70 at milepost 211.83 is the most heavily used runaway ramp in Colorado and in the country. For snow and ice technique once the chains are on, see our winter driving guide.
What should a carrier do about mountain routes?
Make the safe descent the easy one. The rules already point that way: you can't schedule a run that would require speeding (49 CFR 392.6), and when conditions become dangerous enough, driving has to stop until the truck can be operated safely (49 CFR 392.14).
- Train new drivers on downgrade technique before their first mountain run, and keep a record of it. Our guide to safety training for truck drivers covers what to teach.
- Keep brakes in adjustment through your maintenance program, not only at inspection time. See how brake violations show up at roadside.
- Dispatch with time for slow climbs, cooling stops, and chain-ups, and back the driver who parks for weather.
- Put chains on every truck routed through Colorado's corridors between September 1 and May 31.
From the risk side, a downgrade is where one shortcut can cost the truck, the load, and a liability claim on top. Physical damage coverage can pay to repair or replace your own unit after a covered collision or overturn. It can't repair a safety record.
How Simplex helps you run mountain routes safely
Safe descents come from trained drivers, maintained brakes, and coverage that fits the routes you run. We help with each.
Driver performance and training
Through our CSA program, our team monitors your drivers' performance and designs the policies and training your operation needs.
A compliance program that keeps checking
Our compliance programs include assigned driver trainings with reminders, maintenance records, and a DOT mock audit with a risk management plan.
Coverage for your own equipment
Physical damage insurance pays to repair or replace your trucks and trailers after a collision, overturn, or other covered loss.
Frequently asked questions
What should you do before driving in the mountains with a CDL?+
What gear should a truck use going down a mountain?+
Why shouldn't you ride the brakes downhill?+
Is there a fine for using a runaway truck ramp?+
Do trucks have to carry chains in Colorado?+
Where this information comes from
The techniques and rules below come from the CDL manual, federal regulation, FMCSA, and the Colorado Department of Transportation, checked on October 16, 2026.
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1
Texas DPS — Commercial Driver's License Manual (DL-7C)
Mountain driving, gear selection, brake fade, the downgrade braking technique, retarders, escape ramps, and hot parking brakes.
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2
eCFR — 49 CFR Part 392
Pre-drive equipment checks (392.7), schedules that require speeding (392.6), and hazardous conditions (392.14).
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3
eCFR — 49 CFR 395.1
The up-to-2-hour adverse driving conditions exception.
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4
eCFR — 49 CFR 395.2
The definition of adverse driving conditions.
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5
FMCSA — Tips for Truck and Bus Drivers
Planning for mountainous routes, downhill speed, and the limits of non-commercial navigation apps.
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6
Colorado DOT — Hot Brakes
Descent tips, runaway ramp use, and no fee or fine for using a ramp.
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7
Colorado DOT — The Mountain Rules
Brake-failure risk, summer ramp use, and the I-70 hot-brake locations.
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8
Colorado DOT — CMV Chain Law fact sheet
Who must carry chains, the corridors and season, chaining rules, and fines.
Written by
Rigo Diaz
Founder & CEO, Simplex Group
Founder and CEO of Simplex Group, with more than 25 years leading the company and helping trucking entrepreneurs navigate compliance, insurance, and the day-to-day demands of running a carrier. Before founding Simplex, he spent more than six years in risk management, experience that continues to shape how he approaches insurance, compliance, and carrier risk today.
Published · Updated
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The safest descent is decided at the summit
Right gear, safe speed, brakes in adjustment, and a ramp you already know about. Get those four right and the grade stays ordinary.
If you want help building mountain-route training, brake maintenance, and coverage around your operation, talk to our team.