Come winter, there are times the law says you have to use chains. Other times it’s just plain common sense.
In many narrow, mountain passes, for example, you can’t drive legally, or safely, without them. In other cold and snowy places they may just speed your trip. Either way, you need to use the right chains, fitted as the maker intended, to get their full benefit.
A critical factor in creating, and maintaining, traction in snow is the percentage of a vehicle’s total weight that sits on the tires that drive. As front wheel drive has replaced rear wheel drive in the car market, and the amount of weight carried by the driving wheels has risen from about 40 percent to 60 percent (and improved all weather radials have been introduced), passenger car snow traction has improved tremendously. But what about trucks?
You probably know that American trucks usually use two drive axles so both actually work all the time. It helps your traction when you lock the two together so the inter-axle differential won’t allow the rear axle to take precedence, or allow either axle with poorer traction to start spinning too soon. You can even get locking differentials that lock side-to-side with an air actuator in the similar way the inter-axle differential lock does. But don’t get cocky just because your tractor drives on four wheels, because when a five-axle tractor-trailer is normally loaded to its maximum gross combination weight, only about 44 percent of that weight total will be on the eight drive tires.
Lug-type tires help, of course, but they may compromise treadwear and fuel economy a bit when running over the road, and they may be noisier than standard rib-type tires. Unless you spend a lot of time in the mud or ice and snow, they are hardly ideal.
The ideal solution is tire chains, which can be installed quickly, offer excellent traction, and can be removed as soon as the need for them is gone.
Chains can keep you from becoming the tractor-trailer jackknifed across the road making everybody, including your shipper, angry. They are the only way for you to drive legally through many mountain passes in Colorado and the higher elevations in Oregon and Washington at certain cold times of year. One of the biggest reasons there is such a law, and the reason it is strictly enforced, is that the passes often have only one open lane in each direction says Doug Jones, customer engineering support manager at Michelin America Truck Tires. Even if those passes – which are marked as needing chains – are clear when you enter, sudden snow squalls can come up and quickly stall any traffic that’s not properly chained up. All it takes is one stuck vehicle to make passage impossible for everyone. State law enforcement officials will be only too happy to give you a ticket for being that one.
Tire chains are sold specifically by tire size. If you are fitting a 275/80 tire with 22.5-in. wheel diameter, tire and chain size should correspond exactly, making them easier to install, and reducing the chance they will shift around on the tire or slap nearby tractor fenders or trailer parts. Chains are made specifically for each tire size so you won’t need to use extra spring or rubber tensioning devices to keep them tight. In a catalogue, chains are listed by specific tire size and will have a specific part number for each of those sizes.
This is a Blue Diamond chain from Security Chain Co. This type pattern not only helps smooth the ride, but is said to offer less chance of affecting ABS wheel sensor readings.
Jones says most manufacturers have a complete line-up. Many offer multiple cross chains for maximum traction or special smaller diameter cross chains for operation at higher speeds. The longest life chains are nickel-manganese steel, popular among drivers who see lots of chain use but want them to last a long time. Another type is the titanium mix, which is much lighter and works fairly well with lighter loads on the tires. These chains limit speed and running time more than the nickel-maganese, but you can extend their life by replacing worn cross-links.
Gordon Bow, an owner-operator from Oakfield, N.Y., carries single drag chains for the back wheels of his trailer, sets of triple chains to cover a set of duals for the tires of the rear drive axle, and a second set of single chains for the outer wheels on the front drive axle. The rear drives get a more thorough chaining up because the torque passes to the rear axle first, then moves forward to the front. Trailer wheel chains help keep Bow from “trailer swing” situations. He also needs them to be in full compliance when the law requires chains on both drive and trailer axles. Some places in California, for example, requires chains on one wheel on each side of one axle of any trailer with brakes.
When it comes to chain terminology, remember that ‘single’ chains are for a single wheel, but ‘dual’ or ‘triple’ chains are designed for dual wheels.
Bow runs semi-lug type drive tires and normally relies on them. He tries not to run when snow is so deep that chains are required, but carries them along so he can safely (and legally) “get down off a mountain” or to a parking spot.
Most truckers just lay the chain down behind the wheel with the outside surface downward. They then back or drive forward over it, then finally grab the free ends on both sides and wrap it around the wheel. Some makers, like Pewag, offer a special clip that allows you to roll the chain around the tire as you move the vehicle. You clip the chain to the diameter of the tire at the front or rear with the chain laying in the right direction. Then, you roll the truck forward if clipped at the rear, or backward if clipped at the front till the chain wraps around.
Jones says most truck chain sets have adjustable fasteners that let you directly adjust their tension when you clip the ends together, thus eliminating the need for separate spring- or rubber-type spreaders. Some makers even provide a screw-type tensioner that makes it really easy to get the chains snug. Gordon Bow’s latest set of chains have adjustable C-shaped cam-type locks that attach to the last link and draw the chains tight “so they won’t be flopping.”
Jones says just because snug is good doesn’t mean tighter is always better. Tensioning cautions are the same with chains as they are when you are fastening down cargo – a slight tension will do the job and is the best method!
Whatever way you do it, don’t take short cuts, say the experts.
There are some truckers out there who will deflate a tire, tension the chain, then pump the air pressure back up. Don’t try this. “It’s a mistake because the chain then digs down into the rubber, damaging the tread,” says Jones.
The trick to perfectly tight chains is not how tight you make them, but how often you make them tight.
Loose chains leave a gap between tire tread and the inside surface of the cross chain that often allows them to pick up rocks. When the rock later works loose, it’s catapulted by centrifugal force (what Jones called “the slingshot effect”), and often damages the tractor or trailer.
Chains shift around the tires and into tread spaces and lose tension, just like wheels seat after initial installation. Better to install chains just snugly, drive 1/4 mile (or the distance specified by the manufacturer in the instructions), and then retighten, just as you retorque wheel nuts after wheels have seated. Make daily retensioning of chains a part of a pre-trip when driving under continuous snow conditions, too. Trying to anticipate the natural loosening process by using too much tension will cost you treadlife as torn tread sections squirm and wear off.
This cable chain from Security Chain is legal in California and Colorado, even though many cable-type chains are not. The design gives a smoother ride and longer life when run for brief periods on dry roads.
When you need ’em
If there’s actually snow on the ground when you roll onto a road that requires chains, there will often be an officer there checking every vehicle.
Actual standards for many other roads vary from jurisdiction to jurisdiction. Ask an officer, call the state DOT or visit its website.
How to extend chain life
Chain life can also be greatly extended if you follow the manufacturer’s suggestion to accelerate slowly and brake gently. Jones says the manufacturers normally recommend a maximum speed of 30 miles per hour. He reports that testing has shown that increasing speed to only 50 mph will reduce the life of your chains by 31 percent. And, that’s if you can stand the noise. Wheelspin when accelerating, or locking wheels up when braking, can greatly shorten life because it can hone sharp edges onto the chain links that will then alsocut into the tread, he says. Any sliding of the chain along pavement, even when cushioned by snow, will wear the metal away very quickly. Obviously ABS, if you have it, will help. In fact, keeping your ABS in good working condition will not only preserve your tires, but also your chains.
Just because there’s snow on the ground doesn’t mean you need chains. As soon as you start seeing a lot of bare paving, it’s probably time to take them off.
Remove the chains, flush them off with water to remove salt or calcium chloride, and hang them up to dry. Finally, spray on some sort of anti-corrosive coating designed to protect bare metal. Once this is done, you can put them back into a burlap bag or box and place in a storage box on your tractor or trailer without worrying about corrosion. Just don’t shut them up until they’re dry.
Jones says most fleets have a formal springtime maintenance program for their chains. Inspect them carefully, replacing bad links and worn cross chains as necessary. Many drivers have found it makes good economic sense to cannibalize and make two worn sets into one good one.
Winter may irritate all of us, and inevitably it’s cold and miserable outside when we need to install chains. But chains can make driving, that would otherwise be very difficult, safe and steady driving, and easy on the nerves. Having them ready and using them correctly lets you take advantage of the whopping increase in traction they provide without damaging either your tires or your vehicle.
For further information contact:
Michelin North America
Security Chain Company
Sun Tech Innovations-Balance Masters
Technology Maintenance Council, ATA