Most Jeeps down here on the Gulf Coast have never seen a hill longer than a bridge or a morning below 30°. Then somebody books a cabin in the Smokies or a ski week in Colorado, and suddenly the Jeep is climbing a 6% grade at 9,000 feet in a snowstorm. It can do it, but a Jeep set up for 95° and humid needs some prep first. Here's what to check before the trip and how to drive the mountains once you're there.
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Get it →Written for the Gladiator, but it's a solid starting list for packing any Jeep for a long road trip.
This post is about the trip: getting a warm-weather Jeep up a mountain and back. For everyday snow driving, which 4WD setting to use, and winter tires, read our Jeep snow driving and winter prep guide.
The Pre-Trip Inspection (Do It a Week Out)
Give yourself time to fix what you find before you're 900 miles from home.
Coolant: Check the Freeze Rating
Down here nobody thinks about freeze protection. If the system got topped off with plain water over the summer, your mix may be weak. Test strips will tell you. A proper 50/50 mix is typically good to about -34°F. Use the coolant type your Jeep calls for. If the 3.6 has been slowly losing coolant, fix that before the trip. Our 3.6 thermostat housing leak guide covers the usual suspect.
Battery: Get It Load-Tested
A battery that's fine at 90° can quit at 10°. Most parts stores load-test for free. If it's four or five years old and tests weak, replace it at home. A lithium jump pack like the NOCO GB40 in the glovebox is cheap insurance either way.
Wipers and Washer Fluid
That blue jug in your garage is probably summer fluid, and it freezes around 32°F. Drain it down and fill with fluid rated to -20°F or lower before you leave. Put on fresh blades too, since Gulf sun cooks the rubber. Mountain highways get salted and you'll go through fluid fast, so carry an extra gallon.
Tires: Tread, Rating, and Pressure
- Tread depth: Check it with a tread depth gauge. Colorado's traction law calls for at least 3/16" (6/32"), and you want more than that for real snow.
- Sidewall rating: Look for the three-peak mountain snowflake or M+S. More on why that matters for the law below.
- Pressure: Tires lose about 1 psi for every 10°F drop, so pressure set in a 75° garage can be 5 or 6 psi low on a 20° mountain morning. Altitude nudges the reading the other way. Check it cold the first morning up there and set it to the door sticker with a good gauge like the ARB deflator/gauge.
Diesel Owners: Fuel Matters
Gulf Coast diesel isn't blended for cold and can gel in a hard freeze. EcoDiesel owners: arrive with the tank low and fill up with winter-blend diesel in the mountains.
Chains vs. Cables vs. Snow Socks
First, what Jeep says: the JL owner's manual calls for traction devices sized for your tire, on the rear tires only, recommends low-clearance SAE Class S devices, and caps speed at 30 mph or the device maker's limit if lower. Bigger tires on a lift change the clearance picture. Our lift kit compatibility guide covers fender and tire clearance.
| Type | Pros | Cons |
|---|---|---|
| Link chains | Most bite on ice and packed snow | Heavy, loud, need the most clearance, rough on pavement |
| Cable chains | Lighter, many are Class S, easier to install | Less grip than links, wear faster |
| Snow socks | Easiest to fit, light, no clearance worries, smooth ride | Wear out fast on bare pavement, less grip in deep slush |
For most Gulf Coast Jeep owners, snow socks are the right call. You may use them once a trip, if at all, and they go on in a cold parking lot without a fight. AutoSock's own size chart puts both 285/70R17 (the factory JL Rubicon size) and 265/70R17 in its HP870 size. That size wasn't showing up on Amazon when this was posted, so buy it from AutoSock or a dealer they list. AutoSock is on Colorado's approved alternative traction device list.
On 255/75R17 tires (the factory JK Rubicon size), the Security Chain Super Z LT is a Class S cable chain that lists 255/75R17, 265/75R17, and 275/70R17. It does not list 285/70R17, and neither product lists the 245/75R17 on a JL Sport.
Check the fit chart against your exact tire size, and practice the install in your driveway, not on the shoulder of I-70 in the dark.
State Chain Laws: Know Before You Go
Colorado is the big one. When the Passenger Vehicle Traction Law is active, every passenger vehicle, 4WD included, needs tires with at least 3/16" of tread that are rated all-weather or winter (the mountain snowflake, M+S, or M/S), or it has to carry chains or an approved alternative traction device. On I-70 between Morrison and Dotsero, it applies September 1 through May 31. During severe storms CDOT can escalate to the Chain Law, the last step before closing the road, and then every vehicle needs chains or an approved device, 4WD or not. Check codot.gov before you leave, since the rules were recently updated.
The Smokies don't have Colorado-style traction laws. The main road through the park, Newfound Gap Road (US-441), is open year-round, weather permitting, but snow and ice can close it with little notice. Check the park's current closures page the morning you drive.
Heading somewhere else? California, Oregon, and Washington all have their own chain rules, so check that state's DOT page.
Driving the Grades
Going Up
Snow-covered climbs are where part-time 4H earns its keep. On a JL or JT with Selec-Trac, 4H Auto handles patchy roads. Save 4L for crawling, like a steep, unplowed cabin driveway. The snow driving guide has the full breakdown of each setting.
Altitude and Power
Thin air means less power: a common rule of thumb is about 3% per 1,000 feet on a non-turbo engine, so a 3.6 at 10,000 feet is down roughly 30%. The 2.0 turbo and EcoDiesel feel it less, since the turbo makes up some of the difference. Plan on slower climbs and don't pass on a grade you can't see over. You'll feel the altitude too, so drink water and take the first day easy.
Coming Down: Engine Braking, Not Brakes
This one catches flatlanders. Ride the brakes down a long pass and they overheat and fade right when you need them.
- Downshift before the descent, not halfway down. Use the +/- on the shifter to pick a lower gear and let the engine hold your speed. If you have to brake, brake firmly to slow down, then let off. Don't drag them the whole way.
- "Trucks use lower gear" signs apply to you too.
- Smell hot brakes? Pull over and let them cool.
- On snow, go slow and stay smooth. Too low a gear on ice can make the tires slide just like locking the brakes. In 4H, engine braking goes to all four wheels instead of just the rear, which helps on slick descents.
Soft Top vs. Hard Top in the Cold
A hard top is the better pick for a winter mountain trip: warmer, quieter, and lockable at the ski lodge.
Soft tops do fine with a little care:
- Expect a colder, louder cabin. Bring layers.
- Brush snow off before driving and before you open a door. Heavy wet snow sitting on the fabric can make it sag, and it all falls into the cab when you open up.
- Cold vinyl windows crack easily. Don't fold or unzip them in freezing weather. Our soft top guide has more on care.
Mountain Road Emergency Kit
Help can be a long way off, and phone signal drops out in the passes.
- Traction boards: X-BULL Gen 3
- Collapsible shovel: Lifeline 3-piece aluminum
- Recovery strap: Rhino USA 3" x 20', used on rated recovery points only. See our trail recovery kit guide.
- Jump pack: NOCO GB40, which also charges a phone
- Emergency blankets: a Swiss Safe 10-pack takes up almost no room. Bring a real wool blanket or sleeping bag too.
- Power bank and offline maps, downloaded before you lose signal
- Food, water, a headlamp, gloves, and a hat for everyone
If you get stuck with the engine running, keep the tailpipe clear of snow so exhaust can't build up in the cab.
Packing Checklist
Before you leave the coast: run the inspection above, practice-install your socks or chains, and swap to the hard top if you have one.
In the Jeep:
- Snow socks in your exact size or cable chains, gloves, and a kneeling pad
- The emergency kit above, plus a tire gauge
- Ice scraper, snow brush, warm layers, and sunglasses (snow glare is brutal)
Every morning up there: check tire pressure, road conditions, and chain law status, and keep the fuel tank above half.
A Gulf Coast Jeep can absolutely handle the mountains. Prep it at home, take the grades slow, and let the engine do the braking on the way down.
More road trip and recovery gear lives on my Amazon storefront.