I purchased Cooper Discoverer STT Pros (37x13.5R17) right before my Moab trip this fall so this is my first winter with them. The previous two years I've had Kanati Trail Hogs which were excellent on snowy, icy roads. The Cooper's are decisedly not excellent. When I bought the Coopers STT Pros I realized they don't have as much sipping as the Kanati's therefore probably wouldn't match the Kanati's on ice,

but the Coopers are nowhere nearly as good as the Kanati's. What is really suprising is that I've read pleny of forum posts and articles where people are stating the STT Pros are a good choice for snow. Do not believe them. They might be good in deep snow, but not for normal winter road conditions.

Snow & Ice Performance Rating 

Cooper STT Pro

1 2


4 5 6 7 8 9 10


Kanati Trail Hogs

1 2 3 4 5 6


8 9 10


STT Pro tread

As you can see, I'm driving on ⅜" of snow and this was enough to turn the STT Pros into ice skates. Ice skates is actually not an accurate comparison because ice skates perform great on ice, a plastic sled would be a more accurate comparison. With a plastic sled you have some say in the direct you travel, but it's not decisive, more of like an opinion, in the end garvity and the snow decide where your sled will go.

The STT Pro's might not be the worst tire for snow but they are below average. If I had to give them a rating between 1 and 10 on their performance on slippery roads, where 1 is a completely impractical racing slick, 10 is a studded tire, and 5 is an average truck tire, a 3 is all they earn. I'd give the Kanati's a 7, maybe 7.5 on snow and ice, they are way better. Even on their second year the Kanati's were very respectable, significantly better than my virtually new STT Pros.

What now? I ordered a tire sipping tool and will see if I can improve their traction.