Review of the Cooper Discoverer AT3-XLT Tire

So you’re thinking about buying a set of all-terrain tires for your truck camper rig. That’s great that you’re doing research beforehand, because when it comes to buying tires, most people put very little thought into the selection process and rely on the recommendation from a tire shop sales associate instead. That’s fine if the associate knows his stuff, but some associates clearly don’t. That’s unfortunate, because when it comes to your rig, everything is riding on your tires, literally. Indeed, most 3/4-ton and one-ton trucks weigh a good 7,000 to 8,000 pounds. Add a 3,000 or 4,000 pound camper and you’ve got quite a load resting on that rubber. It’s scary when you really think about it. If anything were to happen to one of those tires at highway speed, it could be a disaster. Sure, those who roll with a dual rear wheels have a little more room for error, but not much, because most have even heavier campers with multiple slide-outs. This is a review of the Cooper Discoverer AT3-XLT all-terrain tire.

One of the great things about owning a 4×4 truck camper rig is its ability to go practically anywhere. This means that you need a tire capable of rolling on all kinds of surfaces in all kinds of weather. Sure, a good highway tire will work if you spend most of your time traveling on pavement, but if you’re the more adventurous type, like us, you want a rig that can roll on both pavement and dirt—on a whim. This means your truck needs to be outfitted with a good, jack-of-all-trades tire that is up to the task. In other words, a good all-terrain tire. One of the best, most highly rated all-terrain tires in today’s market is the Cooper Discoverer AT3-XLT, a remake of a classic that earned SEMA’s 2018 New Product Award.

What makes the Cooper Discoverer AT3-XLT better than the other makes of all-terrain tires? First, Cooper Tires is a trusted name in the automotive industry. Based out of Findley, Ohio, the American-owned company has been in business for over 100 years. Even though the Discoverer AT3 has been in existence for over 40 years, Cooper launched an improved Discoverer AT3 in 2018, consisting of three distinct tires made for specific vehicles and purposes—the 4S (Four Season) for SUVs and light-duty pickups, the LT (Light Truck) for medium- and heavy-duty trucks, and the XLT (Extreme Light Truck) for extreme hauling and aggressive off-roading. In all, the Discoverer AT3 comes in 58 sizes from 15- to 20-inch and in three load ranges, including the coveted Load Range E used by most truck camper owners. While designed for hard-core use, the XLT still comes with a 60,000-mile warranty and is available in 29 sizes.

It’s apparent at first glance that the Cooper Discoverer AT3-XLT is not your average, all-terrain tire. The AT3-XLT sports an aggressive tread that stands out more than the “ho-hum” treads found on many other makes. It’s constructed using an innovative silica-based tread compound and Cooper’s Secure-Grip five-rib, all-terrain pattern to provide off-road driving capability and excellent traction in both wet and dry weather. The tire’s zigzag sipes and uniquely-shaped deep center grooves not only improve vehicle stability, while reducing stone retention, but also reduce incidences of hydroplaning. If you don’t think a truck and camper can hydroplane at highway speeds, think again. If an 18-wheeler can hydroplane, a one-ton pickup truck hauling a 3,000-pound truck camper surely can.

Cooper engineers upgraded the Discoverer AT3 with a number of important features. The best is what Cooper calls its “Durable-Tread Technology” that not only enhances its durability on both dirt and gravel, but also helps it stop better than other makes of tires—at least 10 feet shorter on wet roads and over 20 feet shorter in snow. The AT3-XLT also features a “Rugged Traction Shoulder,” which has big side-biting cleats that grip onto rocks while at the same time providing additional resistance to abrasions and cuts when driving over sharp rocks. This special shoulder consists of staggered side lugs called “Earth Digger Edges” that provide additional leverage to plow through loose dirt and sand or sticky mud. In addition, this mud and snow rated tire features Cooper’s Even Wear Arc Technology that provides consistent on-road tire wear and better handling, Stone Ejector Ledges that prevent small rocks from drilling into the tread, and “Whisper Grooves” that provide a quieter ride without sacrificing off-road traction.

Tire Specifications

We’ve been rolling with our set of Cooper Discoverer AT3-XLT size 275/70R18E tires since December 2018. This particular size of AT3-XLT tire weighs 57 pounds, has an overall diameter of 33.23 inches, a tread width of 8.9 inches, a maximum load rating of 3,640 pounds, and a tread depth of 16 (1/32 inches). When hauling the camper, we typically run with 65 psi in the front, and 80 psi in the back, the pressures recommended by Ram for our 2013 Ram 3500 truck. To improve the ride with the camper off the truck, we usually run 65 psi in the front, and 45 psi in the back. So far, we’ve put over 8,000 miles on the set, rolling on pavement, dirt, gravel, rocks, and sand in all kinds of weather including snow and ice. In those eight months, we’ve taken our truck camper rig to Arizona, Nevada, Utah, California, Oregon, Washington, and Idaho.

Tire Performance

Most overlanders enlist an all-terrain tire for off-road duty, but the Cooper Discoverer AT3-XLT absolutely excels on pavement hauling a 3,000-pound truck camper. From the beginning we were incredibly impressed with how quiet and smooth the tires ran and that hasn’t changed in the eight months we’ve owned them. On the Nittos we had on our rig previously, the tires always felt “squishy” even when fully aired up, but not these. The Cooper Discoverer AT3-XLT’s are firm and rock solid and inspire a level of confidence that we’ve never experienced before with the other makes of tires. Indeed, this level of confidence never wavered even when traveling on snow and ice and on steep and twisting, rain-soaked mountain passes. Wearability of the Cooper Discoverer AT3-XLT after 8,000 miles is excellent with tread depths of 13 back and 14 front. While this shows an excellent tread wear rate it also shows how weight plays a role in tread wear and how important it is to regularly rotate your tires every 8,000 miles.

Update: Tread depths after 26,000 miles remains excellent with 9 front and back.

How well does the Cooper Discoverer AT3-XLT perform off-road? Incredibly well. We were particularly impressed with how well the tire maintained its grip in both mud and sand. Sure, we sometimes had to air down to 30 psi, but that’s to be expected when additional bite is needed to keep rolling on soft surfaces. But that’s not all. A critical aspect often overlooked in tire design is how well it resists cuts and chips when driving over sharp rocks. In this, the Cooper Discoverer AT3-XLT also excels because of the tire’s large tread blocks and rugged shoulders. Another thing we really like about the tire is it’s ability to maintain grip on steep, rock-covered grades. As you know, maintaining a grip on such grades is crucial to maintaining control, and in this the Cooper’s did amazingly well. Overall, we’ve been incredibly pleased with the tire’s performance off-road aired either up or down.

Are there any negatives associated with the Cooper Discoverer AT3-XLT? We can honestly say after 8,000 miles that we don’t have anything negative to say about the tire. It does exactly what a good all-terrain tire has been designed to do. But don’t expect the impossible with the Cooper Discoverer AT3-XLT. If you’re looking for the all-terrain tire to perform just as well as a mud-terrain off-road, like Cooper’s Discoverer STT Pro, you’ll be disappointed. Still, the Cooper Discoverer AT3-XLT performs much better than a mud-terrain in the all-important categories of road noise, vibrations, fuel economy, and ride comfort to the point that you may never go back to a mud-terrain if that’s what you preferred before.

The Verdict

When it comes to the intricacies of tire construction and design, very few of us are real experts. Still, a good number of us have extensive experience behind the wheel with numerous makes and models of tires, so we know what works and what doesn’t. What makes a good all-terrain tire from a driver’s perspective? J.D. Power looks at five categories when it rates tires—overall satisfaction, tire ride, traction/handling, wearability, and appearance and that works for us too. We can’t provide an honest grade for wearability since we’ve only put 8,000 miles on our set, but in the other four categories, the Cooper Discoverer AT3-XLT not only meets our expectations, but exceeds them. Cooper really outdid itself when it redesigned the Discoverer AT3. This American-made tire can do it all and looks good going it. When it comes to the adventurous, like us, who are always looking to push the bounds of what’s achievable, what more could you want? On a scale of 1 to 5 with 1 being the lowest and 5 being the highest, we enthusiastically give the Cooper Discoverer AT3-XLT a rating of 5 stars. It’s a great tire.

About Mello Mike 621 Articles
Mello Mike is an Arizona native, author, and the founder of Truck Camper Adventure. He's been RV'ing since 2002, is a certified RVIA Level 1 RV Technician, and has restored several Airstream travel trailers. A communications expert, he retired from the U.S. Navy in 2004 as a CWO3 after 24 years, worked in project management, and now runs Truck Camper Adventure full-time. He also does some RV consulting, repairs, and inspections on the side. He currently rolls in a 2013 Ram 3500 with a 2021 Bundutec Roadrunner truck camper mounted on top.

14 Comments

  1. First thing is the Coopers are now Goodyears. The last American tire company.
    I have 32000 on my At3 Tires and they good, I don’t think they perform any better than my Michelin defenders. The contact patches are rather large and sipes are minimal.
    They also have become quite noisy. I will be going back to the Michelins.

  2. Hey Mike, WOW, the tires pressures seem to far apart. 65 front 80 rear. My dealer told me something different. I’d never run 65 up front. That’s cray from what I’ve been told but love to hear more. We run usually 72 to 75 front and 76 to 80 rear, usually 78 rear and I check my tires often while traveling due to weather and altitude which effects tires greatly. I check several times a week at least, I’m always amazed at how much they change. Cold check usually in the morning. Extreme cold they really drop in pressure. Then it warms up and you have to check again. They do not stay consistent. I’ve checked in every situation. We put a lot of miles on our camper in all conditions. It’s really been interesting. I don’t think there is anyway I’m getting 50K on my Coopers. Probably more like 30 to 35K before new ones.
    Thanks Mike, love to hear your and others experience with tire pressures etc… appreciate all your work.

    • Those pressures are the recommended pressures from Ram, which are based upon the max GVWR load of 11,700 pounds, and are the pressures specified on my truck’s door pillar sticker. The difference in front and rear pressures is based upon the load. The higher pressure is needed in the back because this is where most of the camper weight will be found. My recent CAT scale weight had 5,460 pounds front and 6,720 pounds rear. If I had equal weights I would use the same pressures but this isn’t the case.

      • The pressures on the vehicles stickers are highly ride based. I always have found that they are low especially when it comes to winding roads. They don’t take into consideration the handling and the wear. When you apply brakes or when going downhill the weight transfers to the front. Also since the front takes the job of steering extra pressure above the vertical load must be considered.

  3. I am a Cooper tire fan after trying them on my truck with my most recent tire purchase. However, I found the Cooper Discoverer ST MAXX to be a little more agressive than the AT3, which is what I wanted.

    I do not need an M/T tire but do spend a lot of time off road hunting, fishing etc. even when I don’t have my camper on the truck and the standard A/T tire was just not quite aggressive enough and the ST MAXX filled that void. I have about 24,000 miles on them so far and they have been an excellent tire for me. They are 275/70R18’s.

    I did a lot of research and everything kept bringing me to Cooper Tires. My local tire dealer, when asking them for recommendations on which tire I should go with next (they knew that carrying my Northern Lite 8.11 SE truck camper was part of the decision criteria), said without a doubt, the ST MAXX is what they would put on my truck. Where I live here in Wyoming, they said that is the tire they put on 90% of the oilfield trucks that are off road on oil lease roads most of the time.

    At any rate, I think Cooper Tires, regardless of the tread design are a great choice!

  4. Quick follow up…after getting a Second Opinion from Discount Tire today…I’m told that I do NOT have any tread separation happening, but I do have cupping, due to running the tires on a vehicle with bad struts (they didn’t seem that bad…still rode well…no bouncy-bouncy over speedbumps).

    Anyway, evidently the tread separation was bad diagnostics. I’d delete the original post if I could figure out how…Mike, feel free to admin this entire post down.

    Thanks so much,
    Kevin

    • Another follow up. I’m SUPER-happy with the Cooper AT3-XLT tires. After doing the math, I would have been able to get OVER 60k miles out of these tires on my Expedition before they would have been down to 5/32″. They are warrantied for 60k, so I think Cooper is spot-on in their estimates.

      I had 10/32″ tread left after 41,000 miles!

      I’m replacing these (due to the cupping issue from my bad struts) with ANOTHER set of the same exact tire, because they have given me ZERO issues since I purchased them, and because they have been proven in MY real-world testing.

      Nice work, Cooper, on manufacturing a quality tire that holds up under off-road usage as well as lots of highway miles, and does what they claimed it would do. I’ve become a loyalist!

  5. Mike, you have confirmed the selection for my next set of tires. We have the same truck as you and it came with brand new Cooper SST Pro’s. Love the SST’s but would like something a little quieter and better on snow and ice. Our current tires are oversized at 295’s. Have calculated how much our speedo and odometer are off and can live with it. We do like running the bigger tires, height and width under our Cirrus 800. Did you consider going up in size and do you have any comments on slightly oversized tires?

    • I tried 295s with the Nitto Terra Grappler G2s I had on the truck previously, but they rubbed on hard turns. You don’t have that problem with your 295s?

  6. Good review, Mike. I’m on my 3rd set of Cooper AT3’s, having a one generation ago set on the TC with no side biters. As i’ve said, they are the best all-round, not-for-mud tire. Unless you go into deflation mode, the side biters are window dressing anyway.
    The best luck I’ve had were a set of 18’s on our 2011 Grand Cherokee. We started out with the D (P) rated version which had a better ride, and finally the E-rated tire which was overkill and had to be run a lower pressure to retain any kind of ride quality. They wore like iron and worked reasonably well in snow. On the truck when used in sand at very low pressure, they were great with no, “grave digger” tendencies at all. The issue on earlier generations of the AT3 was the crescendo of noise on the final 25% of tread wear. They say, and when ‘they say’, we listen, that the noise problem has been solved on later generations of the AT3.

  7. Thanks Mike for the extra reading material, I’m in recovery mode currently and I have more time on my hands than I have had in 15 years.

    The review and personal testimonial as a current user of the product should be sufficient for many more truck owners to try Cooper. I think the only thing Cooper suffers from is that there not considered to be in the top three brands by those that are not in the know, which is a big part of the market.

    Maybe if sells increase due to forums like this one, Cooper will see the need to expand there line with a few more choices. I need a 235/80/17 for my 6 wheel truck. I could probably go 245 or maybe even 255 and 70 or 75 but none of these sizes are offered in the 17″ category. I believe most duallys are sitting on 17″ wheels and don’t believe that will change any time soon. Cooper needs to provide a tire that guys like me can buy. Cooper is giving away a huge part of the market to it’s competition. I think the time has come to tell the R&D guys over at Cooper to get off there laurels and provide the specification so the production guys can get busy. The demand for the product over time would easily cover expenses related to the introduction of a new product.

  8. Good review of the Cooper tires. I’ve never owned a set of Cooper tires but may give them a try next time around. Currently I’m using Goodyears, the Adventurer all-terrain with Kelvar. They have a very similar tread pattern to the Cooper. Thanks for the good info and we will see you on the road. Tom.

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