Both the General Grabber ATX and the Cooper Discoverer ST Maxx are designed with a bold tread patterns. Though still they both excel in different key (performance) areas. Let’s find those.
As a tire engineer, form my perspective, the General Grabber ATX would outperform it’s competitor here, in nearly all on-road performance metrics, including grip (on both wet and dry conditions), comfort, fuel and tread wear. On the other side, the Cooper ST Maxx shows up with superior traction abilities off-road, though the tire could really use some sidewall lugs.
Table of Contents
Sizes Facts
The General Grabber ATX comes in 14 to 20 inches rims, with following specs.
- Total Sizes: 60
- Speed Ratings: Q, R, S and T
- Load Ratings: SL, XL, C, D and E
- Tread depth: 14 to 16/32″
- Weight range: 28 lbs to 75 lbs
- Warranty: 60k miles
- Review this tire.
On the other side, the Cooper Discoverer ST Maxx comes in 15 to 20 inches. They have following specs:
- Total Sizes: 47
- Speed ratings: Only Q
- Load ratings: C to F
- Weight range: 38 to 70 lbs
- Tread depth: 18.5/32″ on all
- No 3PMSF ratings available
- No tread life warranty
Outer Construction
Let’s start things here with General Grabber A/TX featuring symmetric tread.
This tire in the middle comes with 3 ribs, and they get to make 4 longitudinal channels. So with this orientation of lugs, the tire is able to yield a reliable grip on highways, whilst still providing very heavy off road traction.
Furthermore, as these lugs, have full depth sipes, and studs, they get to provide wet, snow and rocky terrain traction with them. I’ll explain them all in their respective sections.
On shoulder lugs, there are although similar notches and stud holes, they have slightly different siping design, yet with their slanted design they get to offer good enough performance on dry highways (though it can use some wet traction).
The outer margins include staggered edges, sidewall lugs, and heat diffusers, and all of them add to overall biting abilities of this tire on all types of rugged terrains.
Moving on towards the other tire, the Cooper Discoverer ST Maxx gives you a more aggressive overall structure. Let me explain why that’s the case.
This tire although features a similar symmetric tread like the Grabber ATX, the lugs are more spaced apart, having voids that are deeper.
Moreover, they are arranged in a way that you get a very self cleaning tread, providing ample traction on softer terrains.
If you consider the central lugs, you can see how they are placed to form slanted lateral grooves, which join up the outer slightly wider circumferential tread voids. So any mud/dirt that comes in contact with these lugs are broken down by the notches and sharp edges seen there, and move out of the tread fast.
These lateral grooves are also laced with stone ejectors in between, so any dirt particles trying to lodge in, are thrown out.
Though still, overall the shoulder lugs form a even more aggressive pattern, as these studable lugs carry thicker interlocking sipes, and chamfered edges and the wider gaps they make have bolder stone ejectors in between them.
Moreover, towards outer edges, each lug is staggered on itself, so you get a lot of small mud scoops all over the ribs.
Inner Construction
Durability is crucial for off-road tires which have to perform well on rough terrains, filled with puncturing objects. That’s why tires are given with powerful outer and inner construction.
And considering those, it makes sense why Cooper Discoverer ST Maxx with 3 ply polyester sidewalls yield superior protection.
The General Grabber ATX on the other side although only comes with 2 ply sides, it’s still not too far off, thanks to it’s thicker sidewall lugs (protecting the most vulnerable part of the tire).
The ST Maxx, on the other side, could really use some sidewall lugs on the other hand.
Winter Traction
Winter traction is determined by several factors including performance metrics like the grip, acceleration, lateral traction, and so on, and the various types of surfaces like ice, and shallow or deep snow.
And looking at them all, its pretty safe to say, that the General Grabber ATX is a better tire here. That’s why the tire also has 3 peak mountain snowflake rating unlike its counterpart.
The Cooper Discoverer ST Maxx on the other side, only does better on deeper snowy terrains, and lacks on packed up snow.
And its a big no for this tire when it comes to icy terrains, though that can be fixed by installing studs, as it comes with stud holes, which can give you an extra grip on ice, (also common with Grabber ATX).
Must Read-
Are A/T tires good in Snow: https://tiredriver.com/are-all-terrain-tires-good-in-snow/
Dry Performance
Evaluating the dry performance of these off-road tires, I measured 3 key factors: Grip, steering and the tire’s cornering abilities. Let me discuss them all.
Dry Grip
Grip is the easiest to achieve for these off-road tires, as they both have ample biters to grab the surface of the tar.
Though compared to Grabber ATX, the Cooper ST Maxx still lacks a little bit.
That’s because the middle area of the tread makes the most contact with the surface, and it’s wider lateral grooves there, don’t allow for enough rubber to road connection (to create as much frictional forces, as its counterpart).
General Grabber ATX on the other side, makes a more “highway” streamlined design with it’s interlocking lugs providing a closed up tread pattern and better uniformity.
Steering Response
How continuously is the central and outer section of the tread is meeting with the road, tells a lot about the tire’s steering feedback. That’s why with more aggressive tread designs, the steering sensitivity gets compromised.
And so its not surprising to see why out of the two, the Cooper Discoverer ST Maxx lacks more, despite both of them having similar structural weight.
(Greater weight accounts for a bigger inertia, causing over and under steering which also affects steering feedback times).
On the other side, with a closed up arrangement of lugs in General Grabber ATX, the tire makes a stronger and connected bond with the road, as it rolls.
Its lugs don’t get to flex as much, and they stay stable and more “responsive” comparatively.
Dry Handling
When a tire corners, the whole weight gets shifted towards outer edges. So how well shoulders meet up with the road is crucial in determining the handling efficacy.
That’s why, with smaller lateral shoulder voids, the General Grabber ATX yields better lateral g forces, relatively.
On the other side, the hybrid structure of Cooper ST Maxx with mud-terrain-like shoulders can not supply similar handling abilities.
Wet Traction
The overall wet performance of a tire is a combination of grip, and hydroplaning resistance, and both are equally important for removing water, coming between the tread and the surface.
Now although the Cooper Discoverer ST Maxx yields better hydroplaning resistance, due to it’s more open design, (allowing better water removal, especially from sideways), it’s wet traction overall is still not impressive, as the tire comes with less-effective siping, and there aren’t too many of them (sipes) to begin with.
In comparison, the Grabber ATX comes up with a lot more full depth siping slits, capable of clearing off water with much more efficacy.
Fuel Consumption
Although there’s a minor difference between the weight of both tires, the Cooper ST Maxx still gets to consume more fuel, due to it’s softer tread compound, and larger tread depth. Let me explain why that’s the case.
As the tire brakes, corners, or accelerates, tread lugs tend to move in the opposite direction of the generating force, and with a more pliable construction, this tire wastes more energy in to bending of it’s blocks.
The General Grabber ATX on the other side, comes with stiffer compound, and shallower tread depth, so here lugs focus more on rolling the tire, instead.
Tread Life
With lower rolling resistance, the General Grabber ATX does not rub off it’s tread with as much force as it’s counterpart, showing superior tread mileage.
But the thing is, the tire is way better here, in fact, it ranks on top here, compared to all other in the category (that’s why I added this tire in list of all-time top A/Ts).
So why is this tire so good?
Well that’s because it comes with a stiffer tread compound with aramid nanofiber reinforced polymers, and Kevlar, which does not burn off too easily.
The Cooper ST Maxx on the other side has a softer compound, and wears much more faster in comparison, though it’s still not that bad considering it a rugged terrain tire.
Must Read-
Do A/T tires wear faster?: https://tiredriver.com/do-all-terrain-tires-wear-faster/
Sand Grip
The Cooper ST Maxx really lacks in providing good enough sidewall lugs, and because of this, the tire’s sand traction takes the back seat here.
On the other side, the Grabber ATX, not only offers larger lugs (on sidewalls), but you also get a lighter overall structure as well, combined with smoother outer edges. All these features allow it to provide better floating abilities, which is the main key factor on this terrain. That’s why you always lower the air pressure down here.
(The main goal is avoid as much digging as possible).
Mud Traction
Mud requires tires to have an open structure, so it can leave out ASAP, without packing up within.
That’s why Cooper ST Maxx with it’s “hybrid” structure, and wider longitudinal grooves offers much better traction on all types of muddy terrains.
In comparison, the Grabber ATX is not able to take on as much mud, as it’s interlocking hook shaped structure invites more mud to settle in, relatively.
Grip on Rocks
On rocky terrains, you need biters + durability. And both are provided better on Cooper Discoverer ST Maxx.
The tire comes with 3 ply sidewalls, with Armor Tek3 construction (which is basically a fancy way of saying it’s 3rd polyester casing’s layer is further reinforced with extra material).
And it presents a ton of biters in the form of in-groove notches and open shoulders, which offer bigger groove mouth to grab the rocky surface more firmly.
The General Grabber ATX on the other side, can’t attack the rocky surface as much, with it’s smaller groove mouth.
Tread Noise
The air flow causes noise, and most of it moves (in and out) through the shoulder grooves of tread. These air particles then strike the walls of the tread voids, and produce what you call “tread noise”.
So it makes sense why Cooper Discoverer ST Maxx with a balder design gets to be louder, whereas the General Grabber ATX supplies a quieter ride.
Road Vibrations
The Grabber ATX is also great with setting down the road bumps in a better way. It has a dedicated layer of polyamide on top of it’s 2 ply nylon cap plies.
And where it’s tread gets to be little harder, this layer still offer better ability to soak up the imperfections of the road in a better way.
The Cooper Discoverer ST Maxx on the other hand, although has a softer compound, which is great at cushioning vibrations off-road, on smooth pavements, its not able to show good enough results, comparatively, because of it’s lugs lacking in overall maneuvering stability.
To Sum Up
The Grabber ATX comes out on top, when it comes to on-road grip, fuel, tread (life), and comfort departments.
On the other side, the Cooper ST Maxx off-road performance really makes all-terrain tires worth it.
But the tire really need some aggressive sidewall lugs.
