"The concept of an all-terrain is to have a tire that works well in all conditions, including rain-soaked highways, where mud-terrains sometimes falter," says Ali Mansour with Four Wheeler network. "While the tighter voids prevent most all-terrains from excelling in the mud, for most daily-driven 4x4s, the modern all-terrain tire works extremely well." The increase in traction (versus the street-friendly all-season tire) results in more tread noise, a stiffer ride and lower fuel efficiency. And though the best models can manage deep snow, all-terrain tires tend to be pretty slippery on ice.
That said, there are exceptions. The Cooper Discoverer A/TW (Est. $205) still can't supplant a good winter tire like those profiled in our report on snow tires, but it does represent a good compromise for use in most U.S. climates. Mike Schlee at AutoGuide.com puts the A/TW through tests in summer and winter and comes away very impressed, saying that the it's one of the rare tires that "truly makes me sit up and take notice." He adds that, for winter use, the overall performance gap between it and a dedicated winter tire is the smallest he'd seen in an all-season tire. The results of his summer tests are even more upbeat. He finds nearly nothing to gripe about with performance on wet and dry roads, or when off-roading. "The Cooper Tire Discoverer AT/W may not be the cheapest tire on the market, but in my experience, it's one of the best," he concludes.
One reason that the A/TW is so good in winter is that it's one of the few all-terrain tires to carry the snowflake severe winter rating symbol. That means it has about 10 percent more acceleration grip on the white stuff than a standard tire, reports Ken Brubaker at Four Wheeler Network. He adds that the manufacturer claims that the A/TW far exceeds those standards, though his ability to vet that personally had been limited at the time of his review. However, he does test out the tire in the summer: "We put thousands of road miles on the tire throughout the summer and found it to be a well-wearing, very smooth tire," Brubaker says, adding that performance was good on both wet and dry roads, and that it nicely survived being "purposely mistreated" off road.
The Discoverer A/TW is also put on the test bench by ConsumerReports.org, and does well enough to rate as one of a handful of Recommended choices. It rates Good or better on every measured parameter, including a Very Good rating for snow traction.
One factor gave us a little hesitation in naming the A/TW our Best Reviewed choice. There are very few user reviews, at least on the U.S. side of the border. But up north, in Canada, it's received a warm reception from drivers used to tackling frosty roads. Customers reporting at Canadian Tire give the A/TW a 4.4 star rating. Some of the nearly 60 that weigh in aren't as impressed as the experts when it comes to winter performance, and a couple complain that their tires developed dry rot (cracking between the treads), but every other owner rates the tire at 4 stars or, mostly, 5 stars.
If dealing with icy roads isn't a concern where you live, or a factor in what you are looking for in an all-terrain tire, the Cooper Discoverer A/T3 (Est. $130) still qualifies as a good choice. Ken Brubaker of Four Wheeler network tests the tires at a Cooper Tire test facility and comes away pretty impressed. Testing on identical Chevy Silverado pickup trucks, two with competitors' tires and one with the Coopers, the AT/3 "had the upper hand" on wet pavement. Though not a mud tire, he also mounts the tires on a Jeep Wrangler TJ and gives the tires a go on the test facility's "mud traction area." He says that while not much was expected, "Imagine our surprise when the Cooper Discoverer A/T3 showed itself to be amazingly capable in the goo."
At ConsumerReports.org, the AT/3 scores well in many of the attributes off-roaders most care about, including braking on dry surfaces, resistance to hydroplaning, handling and ride comfort. It's traction in snow is also fairly decent, however braking performance on ice is fair at best. That leads that reviewer to conclude that the AT/3 is "A very good choice for areas where icy roads are rare."
The main focus of a mud tire is typically one thing: ultimate off-road traction. If you're using your four-wheel drive as your main vehicle, however, your tire also needs to have decent pavement manners. "We believe a good mud-terrain tire should perform well in all versions of terra firma; after all, mud only happens when dirt and water mix. The rest of the time, you have dirt, rock, sand and snow -- not to mention all forms of pavement," says Robin Stover from Four Wheeler network.
Experts recommend the Goodyear Wrangler MT/R with Kevlar (Est. $265) because of its balanced performance both on the trail and on the street. Unlike some knobby mud tires, experts say the Goodyear Wrangler MT/R with Kevlar is smooth enough for daily drivers. "The on-road manners are pleasant and relatively quiet, with none of the vibration or harshness we expect from tires with high void ratios," says Four Wheeler network. In a separate road test, Robin Stover with Four Wheeler network says, "The MT/R hooked up in every area of our test loop at Hollister Hills, yet returned one of the smoothest ride qualities of the group." TruckTrend.com reports that "the highway ride remains surprisingly quiet, with none of the drone of some of the more aggressive off-road tires on the market." However, not all owners agree: On a TireRack.com survey, the Goodyear has the lowest tread noise scores among otherwise top-rated maximum-traction tires. For winter driving, the tires perform well on snow, but only so-so on ice.
"Goodyear included Kevlar fibers (in) the MT/R's sidewalls to add puncture resistance," says Four Wheeler network. However, some owners complain that this durability doesn't extend to treadwear. Many report getting 40,000 to 60,000 miles out of a set of Wrangler MT/R's. Goodyear doesn't include a treadwear warranty for these mud tires: Their six-year warranty protects only against defects in the workmanship or materials.
While there aren't a lot of expert reviews, for maximum off-road traction, we found a ton of positive user feedback for the BFGoodrich Mud-Terrain T/A KM2 (Est. $250). It's the top-rated off-road maximum traction tire among TireRack.com customers, based on nearly 300 user reviews and more than 5.5 million driving miles. In an older review, Four Wheeler network tests the tires and Douglas McColloch is impressed with performance over most surfaces -- though they do struggle a little bit on loose dirt and dusty silt beds if driven at high speeds. The "bottom line," he says is that these tires are "a superior rock tire that also excels in mud while still retaining perfectly respectable street manners."