Tire Test: Cooper Discoverer AT3 XLT

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Updated Apr 25, 2019

Cooper Discoverer AT3 XLT tire

Early last year, Cooper Tires expanded its A/T3 truck tire lineup with fitment that more specifically targets usage segments while offering plenty of tread options for a variety of surfaces.

Scott Jamieson, Cooper’s director of category management, says the A/T3 lineup previously featured one tire slotted for multiple uses. However, consumer research dictated that Cooper needed a unique segmentation model that would see the development of three distinct tires focused on specific needs.

The end result was the birth of the Discoverer AT3 4S for SUVs and light duty pickups used for commutes and all-weather weekend adventure; the Discoverer AT3LT for medium-to-heavy duty pickups that haul and tow heavy work loads; and the Discoverer AT3XLT for lifted pickups capable of extreme hauling and aggressive off-roading.

I mounted a set of AT3 XLT (275/55R20) provided by Cooper last month to a 2017 F-150 for an extended test throughout this year. Over the coming months, these tires will spend plenty of time on asphalt highways, muddy logging roads and everything in between.

Cooper’s Discoverer truck tire has been around for 40 years and Jamieson says much of that tire’s legacy – like long-lasting tread wear and dirt road performance – is found in their latest offering. The LT and XLT tire get a durability boost on dirt/gravel roads, which Jamieson says enables a best-in-class, up to 60,000-mile warranty (I measured 16/32nds of tread depth off the rack).

A unique and proprietary silica-rich tread compound combined with an all-weather contoured tread design improve wet stopping distance by 10 feet. The tread design, Jamieson says, has Aqua-Vac channels in the tire crafted to conquer wet weather and snow, providing grip and responsive control.

Fuel economy on the truck when outfitted with the factory tires was slightly more than 21 mpg, and I expect that to drop some throughout this test. To-date, it’s dropped about .5 mpg, which is better than I expected.

Designed to handle anything that passes for a road, tread wear can be erratic on all-terrain tires. Jamieson says the AT3 was developed with Even Wear Arc Technology, “which means the tire shape is engineered to strategically balance pressure at the tire-to-road contact area, promoting on-road even tread wear and superior handling.”

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My test set has piled up about 2,000 miles over the past month and has expertly handled some unseasonably muddy conditions.

Large side-biting cleats built into the sidewall grip rocks and provide additional resistance to abrasions and punctures when driving through sharp, rocky terrain. Alternating scalloped shoulder blocks, that Jamieson says act as a crankshaft to enable vehicles to plow through difficult loose dirt/sand or sticky mud.

With the added grip, there has been more than one instance that I’ve not had to lock the differential on roads that almost always require it under similar conditions with a less aggressive tire. And the more aggressive tread pattern doesn’t necessarily mean its an unforgiving on-highway tire.

The transition from off- to on-highway has also been remarkable, seamless and quiet thanks to subtle tie bars embedded within the shoulder that create a barrier to road noise for passengers.

The XLT is available in 29 sizes from 15- to 20-inch rim diameters.

Editor’s Note: This post will be updated through out the extended testing period.