BFGoodrich Mud-Terrain T/A KM3 vs Cooper Discoverer STT Pro: The last time we looked into the mud terrain segment, General’s Grabber X3 showed clear competency in summer & winter performances over the highly popular BFGoodrich Mud-Terrain T/A KM3. As these 2 products were designed with more off-road in mind, we would like to explore another popular competitor in this segment which is Cooper’s Discoverer STT Pro. This product was launched in 2015 and has been a consistent performer in the mud-terrain scene. On the other hand, Mud-Terrain T/A KM3 has also been in the mud terrain scene since 2018 and it is considered the premium of all premium when it comes to the off road segment. Without further ado, let’s bring these 2 tires head to head and see who comes out on top!
Table of Contents
Results
Results below were taken from Tire Rack’s Testing Off-Road Maximum Traction Tires 2021 test. A total of 4 tires were tested on Tire Rack’s proving ground. The graph below shows the comparison between BFGoodrich Mud-Terrain T/A KM3 vs Cooper Discoverer STT Pro based on the relevant performance category. BFGoodrich Mud-Terrain T/A KM3 was set as a reference hence at the 100% mark.
As both tires are classified as an all season tire with a M+S label, Tire Rack has included snow & ice in its testing portfolio. A detailed testing on snow including acceleration, braking & handling were provided. There are however no off road tests this time around and we have to depend on the snow & ice test for hints. The tire size of interest is a LT 265/70R17 which is a common tire size for Chevrolet Silverado 1500 & Toyota FJ Cruiser. You can check out our latest tire size table for more information. The testing vehicle is a powerful 2018 Ford F150 4×4.
Wet
The friction of coefficient of the tire/road dramatically decreases in wet roads compared to dry roads. Hence it is more likely to get into a road accident during wet conditions rather than on a sunny day. It was so important that the EU label has wet braking as one of its three criteria. Mud terrain tires are usually not known for its wet braking capabilities as it has a low contact area due to the large voids for off road usages. From the wet braking test, Discoverer STT Pro out-brake Mud-Terrain T/A KM3 with a braking distance difference of 4.2 feet (1.3m) !
The advantage in wet conditions continued in handling as Discoverer STT Pro had a 2 seconds advantage in lap time against Mud-Terrain T/A KM3. For the subjective wet handling rating, Discoverer STT Pro fared better with a subjective score of 6.2/10 compared to 5.75/10 of Mud-Terrain T/A KM3. Overall, it can be clearly seen that the Discoverer STT Pro is much stronger in wet compared to Mud-Terrain T/A KM3.
Discoverer STT Pro:
- +2.7% in wet braking
- +2.3% in wet handling (subj)
- +4.9% in wet handling (lap time)
Dry
As for dry, safety is usually not an issue as the braking distance is much longer than wet. However this is the default daily usage and the tires have to perform at a very consistent level. While things overwhelmingly favored Discoverer STT Pro in wet, there was not much difference between the 2 tires when it comes to dry braking. Discoverer STT Pro managed to brake 0.3 feet (0.1m) earlier compared to Mud-Terrain T/A KM3 from a speed of 50mph (80km/h) down to 0. Both tires are really similar when it comes to dry braking performance.
Discoverer STT Pro:
- +0.3% in dry braking
Noise/Comfort/Ride Quality
When it comes to mud terrain, noise, comfort & ride quality is usually the lowest priority. With such a large pattern void, air pumping is at its maximum for mud terrain tires. This would result in a high level of noise due to the air vibration generated by the air in the grooves.
In the end the scores for both tires are really close but at a very low level compared to AT or ATR segments. Mud-Terrain T/A KM3 came out slightly ahead at 5.5/10 rating compared to the 4.8/10 rating of Discoverer STT Pro with ride quality being the main differences.
Discoverer STT Pro:
- -3.4% in average of Noise, Comfort & Ride Quality.
Snow
As both tires has only the M+S logo on it, they can not be legally certified as a snow tire. Only 3 peak logo certified tires require both tires to pass a certain threshold of snow traction level as determined by the legislation. However as Tire Rack did not test off road, snow performances would give us a good indication on how well the tires perform off road.
Discoverer STT Pro showed its advantages in snow by beating Mud-Terrain T/A KM3 in all snow tests with a close margin. It stopped 2.16 feet (0.66m) earlier than Mud-Terrain T/A KM3 from a speed of 25 mph (40 km/h) to 0. It was also extremely good when it came to snow acceleration as it took 1.41 feet (0.43m) less distance to accelerate from 0 to 12 mph (20 km/h). While it was also marginally quicker in lap time (0.1 seconds) and also subjectively slightly better in snow handling (+0.08 points). Overall, Discoverer STT Pro has a slight edge over Mud-Terrain T/A KM3 in snow.
Discoverer STT Pro:
- +3.1% in snow braking
- +3.5% in snow acceleration
- +0.4% in snow handling (subj)
- +0.1% in snow handling (lap time)
Ice
With such dominating performances in snow, we would expect this to continue in ice. The results were totally the other way round as Mud-Terrain T/A KM3 out-brake Discoverer STT Pro by 13.6 feet (4.1m) from a braking speed of 12 mph (20 km/h) to 0. This was the largest deficit we saw on the whole test !
Discoverer STT Pro:
- -17.1% in ice braking
UTQG rating
We have previously shown that UTQG tread wear rating can be a good indication of your expected mileage. As both products are releasing their sizes based on the light truck (LT) designation, UTQG rating is not mandatory. It was also noted that both tires do not provide any mileage warranty which is strange from my point of view. MT tires usually come with really high tread depth and this could be easily a marketing point.
For more in depth information about UTQG, please check out this article here. We even have a free download on the latest UTQG values from the leading tire manufacturers.
Price
Being the undisputed technology leader, we would expect BFGoodrich (Michelin) to command the highest priced tire in the market. This was in alignment as Mud-Terrain T/A KM3 was 34 dollars more expensive than Discoverer STT Pro.
Tire size: LT 265/70R17
Mud-Terrain T/A KM3: $327
Discoverer STT Pro: $293
Difference: -12% more cheaper for Discoverer STT Pro.
Summary
Overall, Discoverer STT Pro performs really well in wet & snow surfaces. Mud-Terrain T/A KM3 on the hand was good in ice & noise. Overall there is no clear winner from our point of view and it comes down to your budget and main target requirements.