Winter Traction Technology: Tire Chains
By Kevin Miller
Tire chains are supplementary traction devices, installed on a vehicle’s drive wheels to give traction on compacted snow or ice.They usually become necessary in the Pacific Northwest about once a year, and then fade out of motorists’ memory until the next snowfall. Readers in other parts of the country may be unfamiliar with tire chains for passenger cars, so I’ve written this handy piece so you can see what you’ve been missing. While tire chains do assist in giving traction, using them is about the least fun you can have in a car in the snow.
Regional and online tire retailers sell varieties of tire chains for vehicles based on tire size and vehicle weight. The past decade has seen widespread introduction of “quick fit” type tire chains, which have replaced cable chains on most passenger vehicles. “Spider Spike” type chains are available for some vehicles which have limited clearance in wheelwells, and these require a carrier to be installed for the season on the vehicle’s wheels; the carrier allows a circular chain assembly to attach on the tire from the outside, without any parts fastening inside of the wheelwell.
The tire chains reviewed here are “Quick Fit Diamond Style” chains, purchased from regional tire retailer Les Schwab and fitted to my 2001 Saab 9-5 sedan. The chains were purchased around the time the car was new, and have ridden around inside of the spare tire under the trunk floor ever since, with the rare exception of the two previous occasions they have actually been used. Such tire chains typically cost between $30 and $60, depending on tire size.
While I had the luxury of installing the chains in my shoveled driveway for this story, they are typically installed in a snowy parking lot or on the slushy shoulder of a roadway. The set of chains I own came with installation instructions printed on a large plastic sheet, which can be used as groundcover when kneeling down to install the chains. Installation requires shoving the colored cable behind the tire, then reaching around the tire (essentially giving the tire a hug) to grab both ends of the cable and fasten them together at the top of the wheelwell. The front of the chain assembly can then be hooked and tightened (after the cable is shoved behind the tire). It is a cold, dirty task. After doing that on both sides of the car, it the vehicle must be driven forward and then the chains re-tightened. By this time, exposed fingers will be burning from being wet and cold, and touching cold metal.
Driving with the chains is an interesting experience. The packaging and instructions are marked with the warning to not exceed 30 MPH, to not drive on bare pavement, and to not spin the tires. While in severe conditions it is easy to not drive faster than 30 MPH, this is easy to ignore when conditions improve. Moreover, vehicles often need to be chained up in order to drive on neighborhood streets, but once well-traveled arterials or highways are reached, the pavement is bare. Because the chains are such a hassle to install (and subsequently remove and reinstall if driving out of the neighborhood, into town, and back home), drivers who have taken the time to install the chains usually tend to leave them on until they are absolutely no longer needed.
During snowy weather in the Northwest, it is common to see passenger vehicles, transit buses, and delivery trucks driving on wet freeways with tire chains on at 50-60 MPH. It is also common to see broken chains in the middle of the freeway that have fallen off of vehicles, either because of improper installation or because the chains have broken due to abusive driving on pavement. If the chains have broken and come off of the car, it is likely they have caused body damage by beating against the side of the car while they were in the process of breaking and falling off.
In my Saab, I disabled the Traction Control System (TCS) when driving with chains, because the front wheels tend to slip, which causes the TCS to reduce power to the front wheels. It was easy to spin the chained-up tires in the wet snow. Of course, driving with chains installed eliminates any sort of steering feel, replacing it with vibration and noise which is felt both through the steering wheel and heard through the entire vehicle. The unpleasantness of experiencing that vibration, though, is offset by remarkable traction (for both acceleration and braking) on roads covered with compacted snow or ice. During a previous winter season, these chains on the 9-5 got our family up steep, unplowed roads on a weekend trip to Portland without incident.
Of course, tire chains are intended to be installed on the driven wheels of a vehicle. If used on all-wheel-drive vehicles, the vehicle’s manual typically specifies where to install the chains. Both Subaru and Volvo specify that tire chains must be fitted only to the front wheels of their AWD vehicles. During our recent storm, I saw a late-model Mercedes-Benz E500 sedan with chains on its back wheels, but the chains were having a difficult time finding traction as they were being overpowered by the motor. I also drove past a front-wheel-drive, Plymouth Voyager minivan with cable chains installed only on the rear wheels. Evidently the driver didn’t know enough about her van to realize that it was front-wheel drive and that the chains needed to be on the front tires.
So why are tire chains so popular in the Pacific Northwest? It is because regional municipalities lack sufficient snow removal equipment to clear the roads. Only state-maintained Interstates and cities’ most-traveled arterials ever see snowplows. Side streets and even secondary arterials are simply untouched, leaving motorists to fend for themselves. The past two weeks have seen unprecedented amounts of snowfall in the region, resulting in the term “Snowpocalypse” being coined to refer to the recent weather which paralyzed the area for most of two weeks.
The City of Seattle’s snow removal policy is typical of other cities in Western Washington. The city’s Department of Transportation doesn’t salt roads, stating that it is ecologically damaging to the region’s waterways. The city’s snowplows also have rubber blades at the bottom, so as not to damage pavement when plowing. That means the plows are simply scraping off the unpacked snow from the roadway, intentionally allowing packed snow and ice to build up. Sand is often (but not always) applied to streets plowed in this way, so motorists are essentially driving on compacted snow or ice until it melts. As the surface melts and re-freezes, the roadway becomes severely rutted, with ice “pot-holes” several inches deep. On a Christmas Eve drive to church on Seattle arterials, my car was scraping its belly on the accumulated compacted snow between tire ruts, and also was bumping over snow irregularities up to five inches tall. It is the roughest surface I’ve ever driven on.
In a Seattle Times article, Alex Wiggins, chief of staff for the Seattle Department of Transportation described the city’s snow removal goals by stating “We’re trying to create a hard-packed surface.” This means that city workers clear the roads enough for all-wheel and four-wheel-drive vehicles, or those with front-wheel drive cars as long as they are using chains, Wiggins said. That’s right. The city only makes streets passable for AWD vehicles or front-wheel drive cars with tire chains. Drivers not so equipped are simply out of luck.
Because the region rarely sees significant snowfall (usually one or two days per year at most), the region tends to just shut down, with people leaving their vehicles parked at home until the snow melts (if they were lucky enough to have been home when the snow fell), or abandoning their cars wherever they reached the limits of traction, whether that location is a parking lot, shoulder, or travel lane. During the recent storm, the City of Portland required drivers to use chains or traction tires when driving within city limits to alleviate the problem of abandoned vehicles.
Mandatory use of tire chains is not unprecedented, as they can be required by state Departments of Transportation when crossing mountain passes in the West. Tractor-trailers are required to carry tire chains, and must often use them when crossing passes. It is uncommon, however, for chains to be required within lowland city limits.
In summary, then, tire chains can provide useful traction on icy or snowy roads, provided they are properly installed and carefully used. The hassle of installing and removing the chains, however, makes them a last resort for traction among many drivers. Snow tires (both studded and studless) are also popular choices for winter traction without the pain of installing tire chains; look for a snow tire review here on Autosavant soon.
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