Cooper Discoverer AT3 XLT Review

The Cooper Discoverer AT3, basically comes in 3 variants, the AT3 4S, the AT3 LT and the AT3 XLT, and they get tend to get aggressive in the same order as well, where the most aggressive version is the XLT, which I am going to be looking here today with you.

Being a tire engineer, from my perspective, although the Cooper AT3 XLT is a made more aggressive, the tire is still better suited for highways as it lacks the durability needed as well as the biters. These biters in the form of staggered shoulders are okay-ish. But in the middle, there aren’t any notches which can grab as much as other aggressive AT tries seen.

What I like about this tire:

• Long lasting tread.
• Impressive sidewall lugs for enhanced tread print.
• Excellent performance on snow, 3PMSF and M+S rated.
• Great traction on highways, in both wet and dry situation.
• Better fuel efficiency and improved noise/comfort.

What can be improved about it:

• Off road performance is not good enough.
• Tire is very weak to be an all terrain, with not strong enough sidewalls.

Tread Design

The Cooper AT3 XLT, as it comes with more aggressive sides, let’s talk about that first.

The other variants of the tire although provide staggered shoulder lugs, they don’t have lugs on sidewalls as this tire.

It’s lugs are thicker and when you air down the tire (to a smaller PSI value), these lugs provide the extra tread print needed for crawling traction.

These lugs are actually joined with the shoulder blocks which are missing stone ejectors due to smaller gaps in between.

And even these smaller lateral grooves have connectors in between, which Cooper calls Whisper Grooves technology (more on that in the noise section, as it’s related to that).

On the inner edges of the shoulder blocks there are sharp teeth (technical term for them is snow vices) and these grab the snow particles to enhance winter performance.

If we check out things in the middle, there’s aren’t many differences.

The tire makes 4 vertical channels here, where the outer are broader and competitive, as they are equipped with snow vices (the teeth you see).

All ribs have block pairs which are connected with each other with rubber underneath (which act as reinforced foundation supports, providing vertical and horizontal traction and grip).

Moreover, all these blocks are installed with 3D full depth sipes (which also have interlock technology).

You can check out other tread features of this tire by looking at the available sizes, at the end.

Compare Cooper AT3 XLT with others

• Falken Wildpeak AT3w.
• Toyo Open Country AT3.
• BF Goodrich KO2.
• Nitto Recon Grappler
• Nitto Terra Grappler
• Sumitomo Encounter A/T
• Firestone Destination X/T
• Firestone Destination AT2
• Kenda Klever AT2
• Hankook Dynapro AT2

Durability

I am putting this section on top, as it’s very important when it comes to Discoverer tires.

Although these are made more aggressive, they severely lack in this area, as it offers you with 2 ply polyester casing covered with 2 steel belts with just a single ply of nylon, where most AT tires come up with 2 or sometimes 3 layers even.

These cap plies are significant as they affect the tire’s lateral stability and strengthens the overall tire’s structure.

That’s why it’s not recommended that you run these tires on aggressive off road terrains, where it can get damaged easily.

On Road Performance

Highway performance is largely based upon the tire’s overall design, from inside and outside.

And considering both, the Cooper AT3 provides you quite some steering response with satisfactory handling stability and overall traction.

Let’s discuss these all.

Dry Traction

Dry traction is further rooted from two factors, where the major portion is taken up by handling (measured by how fast a tire is on curves) and the other part is based on tires grip (calculated by measuring the stopping distances of the tire, when braked from a specific speed, usually 50 mph).

Talking about grip first, the Cooper Discoverer XLT brings forth a very on road aligned values, where if you are coming off an aggressive passenger tire, you are not going to feel a lot of difference.

This has to do with the tire’s ability to make larger rubber print with the surface (the more the rubber exposure with the road, the better the grip).

All of it’s ribs have squared off blocks which have very small lateral grooves between them, and even those have connectors in between, so the tire provides ample dry gripping values.

Moving on towards handling, where the shoulders are considered mostly (as they make the most contact or corners), the Cooper AT3 again supply compactly arranged shoulder blocks with smaller block valleys.

The tire again also has connectors in between as well, so this aids the tire is better steering response and lateral stability.

Furthermore, for the winter performance reasons, its rubber is softer which offers flexibility to overall tread, and this allows it to stick, enhancing grip (that’s why winter tires are so soft).

Wet Traction

During wet traction, the tire’s overall siping design and the tread’s make-up is operative the most. And the good thing about Cooper AT3, is that it provides you with desirable features here.

First, it’s softer rubber (which is also not rigid internally, with less no. of nylon layers), provide the elasticity to the tread. This allows sipes to be more flexible to contract and expand (according to the surface).

Sipe flexing is important because they work by slurping in the water underneath, and bring grip that way (as water is in-compressible, so if not removed a tire can float on it).

Furthermore, Cooper AT3 siping is incorporated with interlock technology, where they have an 3D architecture and they go all they way deep with an wave-like design.

This pattern lock with each other under pressure (during cornering and braking), and they open from one side and close from other, maintaining tread’s flexibility and wiping water away effectively.

In other words, the rigidity of sipes is avoided with this design.

But the tire lacks in another important aspect of wet traction, aquaplaning.

Hydroplaning

Resistance to Hydroplaning or Aquaplaning is the tire’s ability to clear water off from it’s tread voids.

And it affects wet traction a lot because the more the tire evacuates water out, the less water there will be left for sipes to deal with

Now, Cooper Discoverer AT3 with ridges in between the shoulder blocks don’t allow water to move out (from sides) effectively.

But then again these ridges help the tire in Noise a lot.

Fuel Efficiency

Fuel efficiency is dependent on the tread composition, and the rolling resistance the tire generates.

Now in case of rolling resistance, the Cooper AT3 XLT offers a nice balance between grip and friction, meaning it brings forth ample grip without increasing too much rolling resistance values.

So although, it’s not going to provide you with greater efficiency, say, compared to an all season tire, it sure is great in consuming less fuel in all terrain category, comparatively.

With less weight and an on road aligned tread, this tire gives a very satisfactory fuel economy. And out of it’s variants, the 4S is the best one.

Mileage

Like the fuel efficiency, the tire’s mileage also rests upon the rolling resistance values, where Cooper AT3 compared to other aggressive AT tires does better.

The tire also comes with Even Wear Arc technology, where all ribs on the tire gets to put even pressure points across the tread, and this in return produces even wear.

In my experience, on average my sets last about 50k miles, where I mostly stay on roads (as I’m scared of taking them off road, due to their weaker sides, my off road go to tire is Mickey Thompson Baja Boss AT, reviewed it here).

Also, worth reminding, the Cooper AT3 (XLT) comes with 60k miles warranty.

Snow Performance

For snow, all terrain tires have to incorporate some of the tread features of winter tires.

And when it comes to winter tires, you have to understand that they are soft, have flexible tread, have tons of siping, and are narrow (section width).

And although Cooper AT3 does not provide as much siping, it still earn the 3 Peak Mountain Snowflake rating (like a dedicated winter tire).

That’s because the tire’s tread is very elastic, and though siping is less, it’s still very effective.

On winter terrains, in order to make a solid grip, snow to snow contact is crucial. And so Cooper AT3, with sipes (having elasticity, and flexibility) grab in the snow particles, where helping these sipes are lateral grooves, and snow vices (seen on outer circumferential grooves), which don’t allow snowflakes to leave easily.

The trapped snow in the grooves then sticks on the ground underneath with ample friction.

Off Road Performance

All terrain tires need to perform well off road. That’s the reason they are made.

But some terrains get very tough and with a less aggressive design, even some AT tires aren’t able to execute ample performance.

And Cooper AT3 is one of them (well except for sandy terrain).

Muddy Terrain

Let’s start with the toughest terrain out there, mud (the reason why mud terrain tires exist).

And here, mud to mud contact is not what you want, as there is no friction in that. You need rubber to mud contact and this requires fast self cleaning of the tread.

Now Cooper AT3 XLT has a little problem. It’s longitudinal grooves are wide enough and deep enough too (going up to 17/32″), but the tire does nothing for escaping mud sideways.

The interconnected lateral tread voids are not wide enough for mud to leave from one channels to another. And as the shoulder blocks are laced with Whisper Grooves Technology, mud gets trapped there, and traction gets limited.

But in the tire’s defense, it still has staggered shoulder blocks which act as mud scoops, and with it the tire is at least capable of going on lighter mud.

Rocky Areas

Personally, I am not impressed with the Cooper AT3’s performance here. I mean the tire does great here in terms of lateral stability and traction, it really lacks in forward momentum, during climbing.

And like seen in the durability section, these tires wont be able to inspire your confidence too.

But still the good thing is, if you have to take these tires on rocks, you can always pressure them down and they hold up fine with lower PSI pressure values.

With less pressure, the tire’s sidewall lugs also increases the tread’s footprint and they aid in traction.

And of course, the tire provides good enough staggered shoulders which are capable of going on lighter rocky terrains.

Lighter terrains also include gravely roads, and here with cut resistant tread, the tire has no problem. But keep in mind that it’s tread love stones, meaning, they get stuck in the grooves despite the tire having stone ledges (as Cooper calls it).

Sand

Yes, sand, the one off road terrain where Cooper AT3 is simply stunning.

You see, on sand, you need a light tire which is also competent enough of providing you with adequate tread area and this tire permits both.

Being a weaker tire with less no. of layers inwardly, the tire get to be lighter and this helps it on slopes.

With lowered pressure, the tire also gives escalated rubber to sand exposure, where its ribs are already packed together and it’s sidewall lugs provides additional support.

Moreover, the traction scoops of it’s serrated shoulder blocks provide the paddling effect and raises traction that way as well.

Noise

Noise is an considerable factor of overall ride quality, and here the Cooper AT3 offer whisper grooves technology to dampen the levels to a lower decibels.

Noise is just air flow, and most of it comes through shoulder gaps.

Now here, as the gaps are filled with rubber ridges (connectors), air movement is restricted, and overall noise is dampened that way.

Moreover, the tire also offers variable pitch producing tread ribs, where all ribs throughout the tread change in angles and sizes slightly (not visible to eye). And air hitting those create different rhythms (frequencies) which then try to cancel out each other.

To give you an idea, on a E rated tire, you get less than 75 dBs on average, going at 50 mph. (Lower loading ratings would provide you better values).

Overall Ride Comfort

The Cooper Discoverer AT3 provides you with a polymer rich composition which enhances the tread’s stretching abilities.

These polymers (including silica as the main ingredient) issues this tire with the ability to transmit bumps evenly throughout the tread.

Speaking of which, the tread depth also counts here and this tire with 17/32″ yields enough rubber area for bumps to get dissipated out.

The internal construction of the tire also helps the tread ability to absorb shocks further, as it consists of less number of nylon layers on top.

Tire Sizes Available

Cooper Discoverer AT3 XLT does not offer too many tire sizes, as it only comes with 32, where they range from 15 to 20 inches (rim sizes).

All of these sizes are listed below.

Tire Size	Service Description	Load Range	Measured Rim Width	Section Width	Overall Diameter	Tire Width	Tire Weight	Tread Depth
31X10.50 R15LT	109R	C	8.5	10.6	30.2	8.31	44	16.5
32X11.50 R15LT	113R	C	9	11.6	31.42	9.09	48	17
33X12.50 R15LT	108R	C	10	12.6	32.36	9.69	54	17
LT285/75 R16	126\123R	E	8	11.6	32.56	8.9	54	17
LT295/75 R16	128\125R	E	8	11.9	33.35	9.21	58	17
LT315/75 R16	127\0R	E	8.5	12.4	34.49	9.8	64	17
LT305/70 R16	124\121R	E	9	12.2	32.72	9.69	57	17
LT285/75 R17	121\118S	E	8	11.5	33.82	8.9	58	17
LT285/70 R17	121\118S	E	8.5	11.4	32.83	9.09	56	17
LT295/70 R17	121\118R	E	8.5	11.9	33.35	9.41	58	17
LT305/70 R17	121\118R	E	9	12.2	33.86	9.8	61	17
LT315/70 R17	121\118S	E	9.5	12.6	34.33	10	64	17
37X12.50 R17LT	124R	D	10	12.5	36.54	10	68	18
LT285/75 R18	129\126S	E	8	11.5	34.84	8.9	60	17
LT265/70 R18	124\121S	E	8	10.7	32.64	8.62	53	16.5
LT275/70 R18	125\122S	E	8	11.1	33.23	8.9	57	16
LT295/70 R18	129\126S	E	8.5	12	34.25	9.41	61	17
LT285/65 R18	125\122S	E	8.5	11.6	32.56	9.41	57	16
LT305/65 R18	124\121S	E	9	12.2	33.58	10	62	16.5
LT325/65 R18	127\124R	E	9.5	13	34.61	10.59	68	16.5
LT325/60 R18	124\121R	E	9.5	13	33.35	10.63	63	16.5
35X12.50 R18LT	123R	F	10	12.5	34.96	9.88	66	16.5
LT275/65 R20	126\123S	E	8	11.1	34.21	8.9	61	16
LT285/65 R20	127\124S	E	8.5	11.5	34.57	9.69	62	16
LT265/60 R20	121\118R	E	8	10.7	32.52	8.78	57	16
LT275/60 R20	123\120S	E	8	11	32.99	8.9	57	16
LT285/60 R20	125\122S	E	8.5	11.3	33.7	9.69	60	16
LT295/60 R20	126\123S	E	8.5	11.5	34.13	9.72	61	16.5
LT325/60 R20	126\123R	E	9.5	13	35.35	10.59	70	16.5
LT275/55 R20	120\117S	E	8.5	11.2	31.89	8.9	55	16
LT285/55 R20	122\119R	E	9	11.7	32.36	9.69	59	16
LT305/55 R20	121\118S	F	9.5	12.2	33.35	10.31	62	16
35X12.50 R20LT	125\0R	F	10	12.5	34.65	10	68	16.5

Here as you can see, the available speed ratings are R and S, and load ratings go up to F.

Weight ranges from 44 to 70 pounds, while the tread depth stays in either 16.5/32″ or 17/32″.

Take Home Point:

The Cooper Discoverer AT3 XLT is although an aggressive variant compared to it’s other members, the 4S and the LT, it’s still better suited for highways compared to off road.

But still the added sidewall lugs on the tire provides additional support on mild rocky and muddy terrains, where they provide a very well established traction on sand.

The tire is also impressive on snowy terrains and has 3pmsfr.

And of course, on road, the tire shines in all sections, may it be traction (on both dry and wet tarmacs), fuel usage, comfort or mileage.