Cooper Discoverer STT Pro vs ST Maxx vs AT3

All of these tires are all weather. They are highly durable giants made to perform on and off the road. As STT Pro is a mud tire, so none of its competitor is able to beat it off the road.

Comparison of ST Maxx and AT3 is very interesting as both have a closed tread pattern unlike STT Pro. Though AT3 has a higher contact patch but still both these tires have equal rolling resistance, interesting reason behind this fact is discussed in their comparison section.

 ST MaxxSTT ProAT3
Tire typeAll-terrainMud-terrainAll-terrain
UsageOff-road, on-road, all-weatherOff-road, all-weatherOff-road, on-road, all-weather
Tested sizeLT285/75R16LT285/75R16LT285/75R16
Tread depth18.5/32’’19/32’’17/32”
Section width11.7’’11.2’’11.6”
Maximum inflation pressure80 psi80 psi80
Maximum load capacity3750 Ibs3750 Ibs3750/3415 lbs
Weight lbs646154

Tread Pattern

ST Maxx

ST Maxx

The shoulder lugs of Copper Discoverer ST Maxx are of similar shape. All of them have a long zig zag sipe engraved on them with a stud hole. The central part has blocks placed in the sequence of three-two. The two broader blocks have two sipes placed on each, while blocks placed in row of three have one sipe placed on each one. All the blocks are surrounded by wide and deep lateral and longitudinal grooves. The shoulder lugs have the widest grooves in between them and a long stone ejector is also placed between the lugs.

STT Pro

Cooper Stt Pro Off Road

As Cooper Discoverer STT Pro is a mud tire so it has a comparatively open tread design with huge grooves. Two types of lugs are placed in the shoulders, one type of lug has a deep wide space breaking the lug while the other type has a single long sipe engraved on it. Central tread blocks are randomly shaped, some are without sipes while some have a single sipe placed on them. All the tread is full of wide grooves, the grooves between shoulder lugs are the widest while central part also has much wide lateral grooves. This tire has numerous bold and long stone ejectors placed all over the tread. The tread depth of this tire is the highest among all the competitors.

AT3

Cooper at3 comfort

Anyone can identify Cooper Discoverer AT3 as an all-terrain tire due to its closed tread pattern. Infact compared with both of its rivals, it has the most compact design and higher contact patch. The shoulder lugs of this tire are of various shapes and are placed closely, having narrower spaces in between them. The central part has three tread block rows placed between two major longitudinal grooves. The three rows are divided by narrower longitudinal grooves, all the tread blocks in these rows are separated by small lateral grooves. Sipes are placed all over the tread, there are no stone ejectors available in this tire but the shoulder lugs are connected with each other, using connectors and these connectors work as stone emitters as well.

ST Maxx vs STT Pro

On Road Traction

ST Maxx is the clear winner talking about on road traction. This is due to its much higher contact patch. Due to the closely placed tread blocks its contact patch is increased enabling it to grip well on dry surfaces. Its handling is also much better than the rival due to closely placed blocks in the shoulder lugs. The more area of shoulder is touching the road so the tire provides confident handling while cornering at high speed. The wet traction of this tire is also much better than the rival due to increased contact patch plus deep sipes present all over the tread, the contact patch boosts the grip while sipes wipe the water away from the tread. The hydroplaning resistance of this tire is lower than its rival this is due to its less void ratio. On wet roads it performs well but on flooded roads, a tire needs to have wide grooves, it will also perform well due to its deeper tread but isn’t able to beat its rival.

STT Pro lacks a lot on road, in terms of dry grip and handling. This is because of its gigantic grooves that decrease its contact area with the surface. The contact area is decreased, decreasing the grip as well. Handling of this tire is much poor compared with grip as shoulder grooves are much wider than the central ones, so as a result contact patch from shoulders is very less decreasing the handling ability. On wet tracks the results aren’t much different due to lesser contact patch and less sipes. But this tire has very high hydroplaning resistance and on flooded roads, none of the underdiscussing tire can beat it. This is due to its higher void ratio that allows high amount of water to channel out from the grooves, keeping the tread in contact with the road. But still do not drive this tire at high-speed on flooded roads as due to less contact area its griping ability isn’t much strong.

 ST MaxxSTT Pro
Dry on-road GripHighLow-Moderate
Dry on-road handlingHighLow-Moderate
 ST MaxxSTT Pro
Wet on-road GripHighModerate
Wet on-road handlingHighModerate
Aquaplaning resistanceModerate-HighHigh

Off-Road Traction Comparison

 ST MaxxSTT Pro
Mud tractionModerate-HighHigh
Snow tractionModerate-HighHigh
Ice tractionHighModerate
Rock tractionModerateHigh

Mud Terrain

STT Pro provides really impressive performance on all sorts of muddy areas. This is due to its extremely high void ratio that allows high amount of mud particles to pass from the grooves. The mud particles are grabbed in the tread and are thrown backwards as the tire moves forward. The handling ability is even better than its grip as the shoulder grooves are even wider so when the vehicle is cornering in the muddy areas the mud is easily evacuated through the spaces in the shoulders. This tire due to its higher void ratio can be taken in any kind of heavy mud area without any trouble.

ST Maxx can’t beat its competitor in mud due to comparatively narrower grooves but this tire also performs really well on mud due to its deep tread which allows more mud particles to get in and as the vehicle moves forward these particles are thrown backwards. The handling of this tire is also good due to wide spaces in the shoulders that evacuate mud easily and there are no chances of mud getting stuck in between the lugs due to presence of mud ejectors. But to conclude, the winner is STT Pro due to its extreme void ratio and its rival is also much better but it can’t beat STT Pro.

Snow Terrain

On soft snow STT Pro wins again due to its higher void ratio. The soft snow particles are grabbed in the grooves and as the vehicle accelerates, they are thrown backwards, same as mud particles. This action increases the traction ability of a tire and makes sure that the vehicle moves smoothly. Discussing icy paths, this tire isn’t a good match because of its lower contact patch and presence of very few sipes, its grip would be less due to low contact area and it will provide a very poor handling experience, increasing the chances of skidding.

ST Maxx also performs well on snow due to its deep tread and smaller tread blocks that increase the biting ability of the tire so it grips well on snow and due to the presence of wide spaces in between the shoulder lugs its snow evacuation ability is increased as well. Helping it to move confidently but due to lower void ratio and low tread depth relatively, it stands behind its counterpart.  This tire performs better than STT Pro on ice due to its higher contact patch plus presence of sipes. The high contact patch enhances the gripping ability while the sipes work with deep grooves to wipe the water away, and minimizing the chances of slipping.

Rock Terrain

STT Pro again wins in this section as well due to its higher void ratio and the presence of multiple stone ejectors. The high void ratio increases the biting ability of tire by making the biting surface area greater. The bite power of the tire is increased so it can crawl on rocks. Although this tire has wide grooves so it doesn’t need any stone ejectors as in open voids no stone/pebble particle can get stuck. Still, it has several stone ejectors placed in the shoulders as well as the central part. This increases the overall traction of this tire on rocky surfaces.

ST Maxx also provides very good performance on rocks but due to its lower void ratio its biting surface area is lesser so this will hinder the crawling action of this tire. It has stone ejectors placed between shoulder lugs that will emit stone particles from getting stuck into the grooves. This will improve its handling ability but these ejectors are missing in the central part and the grooves are also narrower so the stone/rock particles will get stuck in the central part and will not only hinder its gripping capability but will also damage the tread.

Comfort

In terms of on road comfort, ST Maxx is the clear winner as it has comparatively lower void ratio. Lower void ratio means lesser space for the air particles as the air collides with the tread walls and create noise. So this tire produces less noise while STT Pro is way more louder due to its much wider voids, which provide much space for air particles to resonate.

STT Pro is comfier off the road as due to its higher void ratio it feels like a lesser inflated tire, and absorbs the effect of jerks. While its competitor is also comfier but can’t beat STT Pro because it does not have wide grooves.

Rolling Resistance and Treadwear

ST Maxx has much higher rolling resistance due to its higher contact patch plus more weight. It requires more energy to be rolled so it isn’t a fuel-efficient tire comparatively. Moreover, due to its higher contact patch it also has more tread wear.

STT Pro due to less weight and lower contact area provides lower rolling resistance. This makes it a fuel-efficient tire and its tread wear is also comparatively lower.

Moreover, as STT Pro has slightly more tread depth so its tread will take more time to wear completely and level with the grooves. While its counterpart will wear out slightly earlier due to its little lower tread depth relatively.

 ST MaxxSTT Pro
Rolling ResistanceHighLow

ST Maxx vs AT3

On Road Traction

The on road dry traction of AT3 is much better than its rival, this is due to its increased contact area with the ground. Its contact patch is higher both from the central part and the shoulders, which leads to its better performance on dry roads. Its wet traction is also better due to its increased contact patch and the presence of numerous sipes which wipe away the water and make sure that the tire stays in contact with the surface. The hydroplaning resistance of this tire is much lower than the counterpart, this is due to its lower void ratio, its tread depth and grooves width, both are lower resulting in lesser space for the evacuation of water. While driving this tire on flooded roads one should be very careful.

ST Maxx also provides good traction on dry and wet roads. But it can’t beat its counterpart in terms of dry traction due to its lesser contact patch, both from the center and the shoulders. It’s wet traction is also comparatively moderate due to lesser contact patch and fewer sipes. But it wins when it comes to hydroplaning resistance due to more tread depth and wide grooves which increase the space for water evacuation, and vehicle can move confidently on flooded roads.

 ST MaxxAT3
Dry on-road GripModerate-highHigh
Dry on-road handlingModerate-highHigh
 ST MaxxAT3
Wet on-road GripModerate-highHigh
Wet on-road handlingModerate-highHigh
Aquaplaning resistanceHighModerate

Off-Road Traction Comparison

On mud terrains ST Maxx performs well due to its higher void ratio that helps to throw mud particles backwards and improve the overall traction of the tire. While AT3 having narrower grooves can only perform well on thin mud, if taken in heavy mud it might get stuffed with mud particles and resultantly the tire won’t be able to grip.

On soft snow ST Maxx wins again due to its wider grooves that throw the snow particles backwards confidently and the open spaces between shoulder lugs help to evacuate the snow without hindering the handling performance. This tire cannot beat AT3 on ice as it has less contact patch and lower number of sipes so it won’t be able to grip as good as its counterpart.

AT3 due to narrower grooves isn’t able to evacuate snow efficiently but the presence of smaller tread blocks increases the biting edges which somehow improve the grip of the tire but still it can’t perform better than its rival. On ice this tire wins as it has higher number of sipes and increased contact patch which helps it to move confidently without skidding.

ST Maxx performs really well on rocks due to higher void ratio that increases its biting power and the presence of bold stone ejectors in between shoulder lugs. Both these properties work together to improve the traction of this tire on rocks, comparatively. AT3 has a low void ratio and it also does not consist any stone ejectors, only thin connectors are available in the shoulders which aren’t enough to stop stone/rock particles from getting stuck into the grooves. So as a result, this tire isn’t able to perform better than its rival.

 ST MaxxAT3
Mud tractionHighModerate-High
Snow tractionHighModerate-High
Ice tractionModerateHigh
Rock tractionModerate-HighLow-moderate

Rolling Resistance and Treadwear

Both of the tires have almost equal rolling resistance, although ST Maxx has lower contact patch so it should have lower resistance than its rival but its weight is much higher than AT3. And AT3 has a higher contact patch but its weight is lower than its rival so both stand almost equal in this section. Both tires will have a slight difference in fuel efficiency.

ST Maxx will wear out later than its rival due to its higher tread depth, its tread will take more time to balance with the grooves base, while its rival will wear out relatively earlier.

 ST MaxxAT3
Rolling ResistanceModerateModerate
DurabilityHighModerate-High

Summary

ST Maxx and AT3 are All terrain tires while STT Pro is a mud tire.

ST Maxx vs STT Pro

ST Maxx:

  • Provides better on road traction.
  • Provides better traction on ice.
  • Provides higher on road comfort.

STT Pro:

  • Has higher ability to resist hydroplaning.
  • Provides higher traction on mud, snow and rocks.
  • Provides better off road comfort.
  • Has lower rolling resistance.

ST Maxx vs AT3

ST Maxx:

  • Provide higher resistance against hydroplaning.
  • Provides better traction on mud, snow and rocks.
  • Has higher durability.

AT3:

  • Provides better traction on the road.
  • Provides good traction on ice.
  • Provides more comfort on road.

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