Tested: Cooper Discoverer STT Pro

Cooper Discoverer STT Pro 285-75-16

The Cooper Discoverer STT Pro has taken the offroad market by storm since it’s release in 2015. The new aggressive tread pattern, sidewall protection and the latest in rubber technology has produced a tire that works great for both off-road and on-road situations. I needed new tires on my baby (a 1986 BJ74 Land Cruiser), and opted to give these a shot…and I haven’t been disappointed.

First, the technical stuff…my biggest complaint on tires is the sidewalls. Cooper addressed this in the Discoverer STT Pro, by combining their Armor-Tek3 sidewall technology with thick shoulder Side Biters to offer protection against sharp rocks and sticks. Normally, this would also mean a stiffer ride as well, even aired down…Cooper managed this with their Flex Groove, which breaks the line between the sidewall and the main tread blocks, allowing the sidewalls to effectively flex and improve the ride. Traction was addressed in their new tread design…large blocks, large voids, a little siping thrown in, and the latest in silica rubber compounds created a tire that works well at a variety of air pressures, effectively wraps around obstacles, and does all this with excellent highway manners and minimal noise.

The tires on my test mule are 285-75-16’s and are wrapped around some 16×8 MT Classic II’s. The rig itself is a 1986 JDM right-hand-drive mid-wheelbase (100″) 4 cylinder turbo diesel Land Cruiser, running factory solid axles on a 2.5″ OME leaf spring suspension and around 200.000 kilometers on the odometer…simply put, about as bad as it can get for on-road handling.

My BJ74 may be a princess when it comes to the sheet metal, but the bumpers, sliders and tires are fair game…

I made a recent trip to Las Vegas, about 200 miles roundtrip. The little turbo diesel struggles to hit 75mph, but it will do it…the Cooper STT Pro’s track straight and true at 32psi. Construction zones, uneven roads and shoulders: no issue. Cracks and grooves in the pavement: no issue. The occasional swerve for trashed semi-tires in the road: no issue. I’m not going to say I can’t hear the tires, since they ARE an open lug pattern….but there is none of that obnoxious drone, none of that pulsing tire noise. They are smooth, and they are acceptably quiet around town and at highway speeds.

Cooper Discoverer STT Pro’s down to 14 psi in the rocks – the sidewalls squatted nicely and helped create a great footprint for the Moab slickrock.

Offroad, I do air down the STT Pro’s a bit more than I normally would….Cooper is known for amazing treadwear (we can’t seem to wear out the Discoverer AT/3’s on our GX470) but compromises a bit with a harder rubber compound. I ran between 10 and 15psi and the STT Pro’s were effectively point and shoot. The slickrock of Moab and Sand Hollow were no match, even when I would deliberately stuff the sidewalls into the rocks. (I will note that I installed them laces out, and the white lettering is getting rough…)

The radio towers 2000′ above Toquerville UT.

Snow in our corner of Utah is rare, but fortunately easy to visit. The Cooper Discoverer STT Pro’s made short work of most of the climb up, but finally ran out of traction. 25psi was a bit much, and dropping to 12psi turned a slick snowy/muddy climb into an easy drive…to this amazing photo spot.

Getting this shot was almost painful…

It may not look like the STT Pro’s cleaned well in mud, but this clay slop was no match for their aggressive tread. Slow starts, slippery climbs and gooey ruts were no problem…they simply found traction and continued forward motion with minimal tire spin. Notice how clean the fenders and bumper remain….idle speed was all that was needed.

Final poser shot on Toquerville Falls

In summary, I’m more than pleased with the overall performance of the Cooper Discoverer STT Pro. On-road and off-road, they have excelled and I’m looking forward to many years of service life!

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