A Colorado-specific winter checklist for BMW, Audi, VW, Subaru, Mercedes and other imports: tires and the traction law, batteries, coolant, wipers, and what to have a shop look at before the first big storm.
Front Range winters are weird. It's 55 and sunny on Tuesday, a foot of snow on Thursday, and dry again by Sunday. That swing is hard on cars, and imports with low-profile tires, big brakes and fussy electronics feel it more than most. Here's what we'd do in October or early November, before the first real storm.
Tires first, and know the traction law
If you only do one thing, look at your tires. Summer performance tires (the default on a lot of BMWs, Audis and GTIs) turn hard and slick in the cold and are not rated for snow.
CDOT's Passenger Vehicle Traction Law can be put in place on any state highway when the weather calls for it, and on I-70 between Morrison and Dotsero it can be enforced with fines from September 1 to May 31. When it's on, you need tires with at least 3/16" of tread that are rated all-weather or winter (the mountain-snowflake symbol or M+S), or you need to carry chains or an approved alternative traction device. CDOT's page has the details and the fines. See the sources below.
Quick check: put a quarter in the tread upside down. If you can see the top of Washington's head, you're at or below roughly 1/8", which is less than the traction law asks for.
- Driving to the mountains a lot? A set of dedicated winter tires on their own wheels is the best money you'll spend. It also saves your nice summer wheels from mag chloride.
- AWD helps you go, not stop. A Subaru or quattro on worn all-seasons still slides in a corner.
- Check pressures after the first cold snap. Pressures drop as it gets colder, and a lot of imports will throw a TPMS light the first cold morning.
Battery
Cold weather is when a weak battery finally gives up. Most parts stores and shops can load-test it for free or cheap. If yours is original and five-plus years old, it's on borrowed time.
On many newer BMWs (and some Audis and Mercedes), a new battery has to be registered to the car so the charging system knows it's new. That's why BMW battery quotes look high. See what owners paid for a BMW battery plus registration.
Coolant, belts and hoses
Ask the shop to test the coolant's freeze protection, not just the level. Look for crusty residue around plastic coolant parts. BMW, MINI and VW/Audi engines all use plastic housings that get brittle with age, and a cold snap can be the thing that finally cracks one. Related prices: MINI thermostat housing, VW/Audi 2.0T water pump, BMW N54 water pump.
Wipers, washer fluid and lights
- Swap in fresh wiper blades. Winter blades or beam blades shed ice better.
- Fill up with a washer fluid rated well below zero. The blue summer stuff freezes.
- Make sure every bulb works. It gets dark at 4:45.
Brakes
Plow trucks spread sand and deicer, and stop-and-go on snowy roads is hard on brakes. If you're close to replacement, do it before winter, not in the middle of it. Our price reports: BMW 3 Series front brakes, Audi A4 front brakes, Mercedes C/E-Class front brakes, Lexus RX/ES brakes.
Keep in the car
- An ice scraper and a snow brush
- A blanket, gloves and a hat
- A phone charger
- Water and a couple of snacks
- A small shovel and something for traction (kitty litter or sand) if you head into the hills
- Chains or an approved traction device if your tires don't meet the traction law and you're crossing the passes
Don't pass the plows
CDOT's plows often run side by side in a tandem formation on the interstates. Colorado's tandem snowplow law (HB19-1265) makes it illegal to pass them in that formation, and it's dangerous anyway: there's whiteout and ridges of snow between the lanes. Stay back a few car lengths, too. They're dropping sand and deicer.
Sources
- CDOT: Passenger Vehicle Traction and Chain Laws
- CDOT: Snow Removal and Safety (tandem plow law, deicers)
General information, not legal advice. Check CDOT and your owner's manual for the rules and specs that apply to you.