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Tire Test: Cooper’s Discoverer A/TW Is an All-Around A/T With Special Winter Skills

Posted in How To: Wheels Tires on March 14, 2018
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Many 4x4s are work trucks, and they need tires too. Case in point: light trucks serving the farming industry. They live a hard life and four-wheeling is often involved. A farm pickup can spend one day schlepping an over-capacity load of seed from the elevator to the grain drill, hauling a combine header from one field to another, getting from one muddy track to another, or pulling tons of harvested grain to the elevator. It’s got to be a roadworthy all-season truck, so tire choices must be balanced according to the local weather.

The farm truck in this case is an ’86 Ford F-250HD diesel 4x4, bought nearly new by the same family that has it now. It’s been an Ohio farm truck since 2002 and was an RV hauler before that. It’s been running aggressive all-terrains forever, and while we had few complaints about tires overall, maybe we really didn’t know what we were missing until we tried Cooper Tire’s Discoverer A/TW.

Cooper introduced the A/TW line into the all-terrain market in 2014 with ten initial sizes. At present, Cooper offers 29 sizes to fit 16-20 inch rims. Fifteen of them are LT rated, all load range E. So yeah, this tire range is biased toward trucks. It’s billed as an all-terrain but it wears another hat, and that’s where the “W” for “winter” in the designation comes from. This is accomplished partly via tread compound and partly from tread design.

Fresh, crunchy snow on a -10 degree F day. It’s nothing new for this old farm truck, but it turned out these tires were a massive improvement over any of the same size A/Ts it had been running for decades.

For any tire to perform well in snow, the tread blocks must not be too far apart. The idea is that if the tread will hold a bit of snow, believe it or not, traction is better on packed snow and ice. Cooper added what they call “Snowgroove 2.0,” which are V-grooves on the outer edges of the tread blocks, and these little guys enhance the tire’s ability to carry snow while being open enough to work well as an all-terrain. There’s a whole lot more science in tread block design that’s beyond us mere mortals. Cooper also spent a lot of time on the siping, which is another tread design element that enhances snow and ice performance. From the tread compound angle, Cooper tweaked the recipe so that the tire could stay pliable right down into the worst of winter temps, and that’s key to grip on ice. All this leads to meeting the ASTM (American Society for Testing and Materials) snow traction performance tests and earning that coveted snowflake over three-peak emblem.

So how do we rate these tires in winter? Top-notch! Tested in Northwest Ohio during a particularly c-c-c-cold cold snap, with temps into the -10 Fahrenheit range and snow as deep as about 5 inches on the flats, driving higher. Through wood tracks and open fields, some of it with a slushy muddy base, the tires did extremely well. On the snow-packed highway, the improvement over the previous tires was dramatic. Repeat, DRAMATIC! Without ABS, the very nose-heavy unloaded diesel pickup is prone to swapping ends on a hard stop or spinning out in turns. Adding a thousand pounds of tractor weights in back was the usual trick, but for this test we braved the icy roads completely empty and were happily surprised at the marked improvement. We been missin’ out!

A lot of technology goes into the Discoverer A/TW tread. Notice the jagged teeth inside the tread blocks. That’s Snowgroove 2.0 that Cooper designed to enhance snow retention for snow-on-snow traction. Siping is another key element and these are scientifically designed to offer great ice grip, but they play a part in wet and dry pavement grip as well. The rubber compound is a key element in the winter performance and it’s a compromise between remaining soft in cold weather and offering good treadwear on warm, dry roads. We don’t know how this will play out long term on our test truck, but the treadwear warranty on the A/TW isn’t quite as long as some of Cooper’s other LT all-terrain tires. A slightly shorter tread life might be the price you have to pay for great winter performance, and only you know if that adds up for your driving situation.

Except for a few hardy souls in the far, frozen north, there is more to a year than winter. We got to test the tires on plenty of wet highways and rate this tire very highly there. On dry roads, tire noise no longer dominates the vintage music of the old-school 6.9L diesel. Particularly noteworthy is braking performance. Again, it’s a pre-ABS truck with drum rear brakes and is normally very prone to locking the rear tires on a hard stop when unloaded. The A/TWs are very grippy and much less likely to lock up on an emergency stop.

As the deadline for this story approached, the winter thaw came, and the truck’s work took it into some of Northwest Ohio’s famous clay mud. If there was any area where we worried a little, this was it. Well, the tire did just fine. They got through everything the more aggressive tires did, and with no drama. This isn’t hard-core-gumbo-mudding, but you can get a pickup loaded with firewood plenty stuck in eight inches of slick mud.

These tires are great at grabbing and holding snow. They are equally great at grabbing and holding gravel. This truck lives down a half-mile-long gravel lane. We had gotten fond of the more open tread A/Ts not grabbing stones and tossing them into low synchronous orbit once the truck gets some speed. But in the end, rock grabbing is pretty typical of any relatively closed tread tire.

So, the bottom line on the Cooper Discoverer A/TW is that for a working truck seeing a mix of terrain in a winter environment, this tire is hard to beat. You can probably find tires that will beat it in specific situations, but you will find few LT-rated all-terrain tires with such a broad range of very strong capability.

This is a good sign! The snowflake on the three-peak symbol reflects surpassing a 110 traction index score on the ASTM F-1805 snow traction tests. This is a performance test, and the 110 means the tire has to deliver 10 percent or better straight line snow traction than a standard reference tire.
It ain’t all about wheeling! There may be more white knuckles involved in driving a pickup on an icy road than there are in wheeling. This is where that snowflake on the sidewall and the “W” in A/TW are most welcome. The road was slippery enough here that the photographer almost did an ass-plant getting out to take the picture. We didn’t try any ice-racing–type driving, but running the truck around in this was a vastly improved experience with the A/TWs. We could go so far as to say the Cooper A/TWs are the best winter tires that have ever been on this 31-year-old truck.
It’s not designed to be a mud tire, but it slogged through both ends of the muddy woodlot trail with a couple of cords of wood. It had enough grip to pull through and we didn’t need to spin it up and see how it cleaned. The shoulder cleats are gnarly enough to pull it through and maintain A/T bragging rights.

Specifications (as tested)

Tire: Cooper Discoverer A/TW
Size: LT285/75R16
Type: All-season winter radial
Load range: E
Max load (lb): 3,750 @ 80 psi
Sidewall construction: 2-ply polyester
Tread construction: 2-ply nylon, 2-ply steel, 2-ply polyester
Approved rim width (in): 7.5-9.0
Tread depth (in): 17/32
Section width (in): 11.6
Overall diameter (in): 32.56
Maximum psi: 80
Weight (lb): 55

Sources

Cooper Tire
Findlay, OH 45840
419-423-1321
us.coopertire.com

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