During winter, a driver is likely to encounter every possible road condition. Learning to properly assess those conditions will improve one’s ability to adapt to them for successful, efficient motor vehicle travel.
The vehicle and how it’s equipped plays the biggest role in winter driving ease. At the top of the list for traction are 4-wheel and all-wheel drive vehicles with purpose-built winter tires. Winter tires have special rubber compounds and tread designs intended to improve grip on cold and slippery roads. The biggest thing to keep in mind is that while these vehicles are superior for going, they don’t stop or turn better than their front-wheel and rear-wheel drive counterparts.
Although front-wheel drive autos have more traction for starting from a stop and going uphill (due to extra weight over the drive wheels), they are actually less predictable and stable for turning and stopping than rear-wheel drive vehicles. Rear-wheel drive cars and trucks have a better front/rear weight balance, but lack traction for starts and hill-climbs.
Depending on where you drive in winter, today’s all-season tires may be satisfactory for your all-wheel or front-wheel drive vehicle. Quality all-season tires have built-in siping and rubber compounds to improve slick-road traction, but winter-specific tires have more aggressive tread patterns and generally softer rubber. With rear-wheel drive, one will invariably face inability to move from stops and on hills at some point during a typical winter without the aid of traction tires or chains.
Some drivers claim an advantage with studded tires on ice, but that has been disputed when compared to the best winter tires. For certain, studded tires have inadequate adhesion on wet and dry roads, producing greater stopping distances and poorer cornering traction than even the cheapest tires in those conditions.
As for “reading” the road, drivers will basically face four road conditions: dry, wet, snowy and icy. Within those categories, however, there are still some variables.
In dry conditions, tire adhesion to the road surface will still vary according to temperature. Essentially the dry-road adhesion will be greater at 35 degrees than it will at 15 degrees. At 5 degrees, traction for cornering will be compromised for any tire, even though the road may be bone dry.
Roads here may be wet from either water or liquid deicer. Obviously, both are more slippery than a dry road, but the one covered with liquid deicer is likely even slicker than one with only water. If your vehicle has an outside temperature display, pay extra attention as it shows near freezing — it can serve as an advance warning that slick roads are about to turn to “black” ice.
Traction on snowy roads also varies greatly based on temperature and degree of packing. Adhesion on fresh snow, at 20 degrees or lower, for example, is actually quite good. As temperature rises near the freezing point, tire adhesion lessens, and can be as slick as ice when packed by traffic. At very low temperatures, the stopping action of vehicles at intersections can turn snow into glare ice — when unexpectedly encountering that condition, search for looser snow at the edge of the road to facilitate stopping.
Icy roads, occurring from frost, frozen fog, melted then refrozen snow, or dropping temperatures of wet roads, are the slickest conditions drivers encounter. Besides lowering speed, remember to make any input to steering, brakes or accelerator as extremely gently as possible to maintain control.
Readers may contact Bill Love via email at firstname.lastname@example.org.