As with any pursuit, one expects unreasonable performance from your equipment, be it a pair of hiking boots, a backpack, or a set of all-terrain tires. Your vehicle needs to work in many conditions, from road trip highway miles to backcountry two-tracks and deep snow. As with that perfect pair of boots, the tires you install on your vehicle will make all the difference once traction deteriorates. Over the past several years, the team at Adventure Journal has been testing and abusing the Cooper Discoverer A/T3–and these are our conclusions from the field.
The Discoverer A/T3 is a thoroughly modern tire. Positioned as a dedicated all-terrain, it stems from technologies such as advanced CAD design and FEA engineering. We have put over 10,000 miles on various sets of A/T3s, including a crossing of Australia with a 200 Series Land Cruiser, a traverse of Western Canada in a 110 Defender, and considerable abuse during military training in our LJ78 Land Cruiser. Our testing has resulted in no punctures or failures.
On the Road
On pavement the A/T3 behaves more like a performance tire. It had consistently short braking distances and recorded fast times in our slalom course. Grip improved even more on wet asphalt, where the Cooper clocked the fastest speed we have ever recorded for an AT on the flooded skidpad. On ice and snow we have found traction is nearly as effective as a winter tire. The A/T3 demonstrated superior ride quality, noise/vibration/harshness (NVH), and skid pad handling; it cannot be overstated how well these tires perform overall on the pavement. While proprietary engineering data from Cooper was not available, we concluded that the excellent pavement performance was a result of high adhesion (softer durometer), lug integrity and stability (shouldered lug design), and aggressive siping.
On the Dirt
The Cooper is a high-speed champ on the dirt. On the dirt oval we were able to manage controlled, four-wheel drifts at speeds in excess of 75 mph; this was 15 percent higher than the second best performer we have tested. The tire responded well to small inputs of the steering wheel, was direct, and inspired confidence. The prodigious grip allowed for effective countersteer and braking on the loose gravel surface. It has a tapered lug shoulder, which resulted in negligible stone retention; a welcome attribute when compared to older lug profiles. We also found lug integrity to be high, and experienced limited chipping or chunking during the test period. The Cooper performs admirably on rock and in eroded ruts, but the rubber composition does demonstrate some compromises. Though adhesion was average, the tire ultimately completed our test climb through a combination of mechanical keying and excellent deformation. Carcass flexibility and conformity is better than average.
The Cooper Discoverer A/T3 is a winner and highly effective all-terrain option. As one of the lower-priced offerings, it is also a genuine value. The cost-saving is no doubt a result of the company being one of the world’s largest tire manufacturers. On the highway the Cooper was direct, quiet, and smooth—a favorite for long-distance cruising. One would think that all of this pavement performance would result in a lackluster dirt showing, but the Discoverer was an animal on the dirt and provided huge driver confidence in mid-to-high speed conditions. This directly translates to improved safety for an overland traveler. The Cooper A/T3 is a best of breed option for the 4WD owner looking to install one set of tires for year-round and all-conditions performance.
High-speed control and predictability on dirt
Greatest range of performance
Best wet-pavement traction
Lacks three-ply sidewall
Where to Purchase
Photos by Scott Brady