Head to head
BFGoodrich KM3 vs Cooper Discoverer STT Pro
This is the cleanest comparison on the site. In every size where both tires are listed in the same load range, the Cooper is lighter and carries more tread. That is a real, documented difference — and it still does not tell you which tire lasts longer.
By Bill Belcamino · Last verified 17 September 2026
What the published data supports
In LT285/70R17, 35×12.50R17 and 37×12.50R17 — each compared at a matched load range — the STT Pro is listed 2.4 to 6.4 lb lighter and 1/32″ to 4/32″ deeper than the KM3. Cooper also states a three-ply polyester casing, Armor-Tek3, where BFGoodrich publishes no ply count.
The BFGoodrich publishes measurable claims against its predecessor and a clearer warranty term. Neither carries a treadwear warranty or 3PMSF certification.
Side by side
Specification
BFGoodrich KM3
Cooper Discoverer STT Pro
LT285/70R17
67.1 lb · 18/32″ · 3,195 lb at 80 psi (E)
62.0 lb · 19/32″ · 3,195 lb at 80 psi (E)
33×12.50R17
67.6 lb · 18/32″ (E)
Not listed in this size
35×12.50R17
74.4 lb · 18/32″ · 3,195 lb at 65 psi (E)
68.0 lb · 21/32″ · 3,195 lb at 65 psi (E)
37×12.50R17
77.4 lb · 18/32″ · 3,525 lb at 50 psi (D)
75.0 lb · 22/32″ · 3,525 lb at 50 psi (D)
Measured diameter (37×12.50R17)
36.5″
36.77″
Casing
CoreGard Max — ply count not published
Armor-Tek3 three-ply polyester, single nylon cap ply
Numeric claims
5% mud, 8% rock, 27% tougher sidewalls — all vs the KM2
None published
Treadwear warranty
None; limited warranty for life of tread or six years
None
3PMSF certification
Not stated
Not stated
Size rows are from the tiresize specification pages; the Cooper’s 62 lb in LT285/70R17 matches Cooper’s own figure. Casing and warranty for the STT Pro are from Tire Rack’s listing; the KM3’s claims are BFGoodrich’s.
Where the published data favours the BFGoodrich
Published engineering claims with a stated baseline: 5% better mud traction, 8% better traction on rock and slick surfaces, and sidewalls 27% tougher on internal puncture testing — all against the KM2. Cooper publishes no comparable figures.
A written limited warranty for the life of the usable tread, or six years. Tire Rack lists no treadwear warranty for the STT Pro.
Availability in 33×12.50R17, where the source lists no STT Pro.
Where the published data favours the Cooper
Mass and depth, at matched load ranges, in every size where both are listed: 5.1 lb lighter and 1/32″ deeper in LT285/70R17; 6.4 lb lighter and 3/32″ deeper in 35×12.50R17; 2.4 lb lighter and 4/32″ deeper in 37×12.50R17. That is unusual — more rubber usually means more mass.
A stated casing. Cooper describes Armor-Tek3, a three-ply polyester casing, with steel belts under a single nylon cap ply. BFGoodrich does not publish a ply count for the KM3.
What the evidence does not establish
Which tire lasts longer. Depth is how much rubber there is to wear, not how fast the compound wears it, and neither manufacturer publishes a treadwear warranty or wear data.
Traction and noise. No independent test covers both, and Cooper publishes no performance figures at all.
A retailer database once listed the STT Pro at 41.5 lb against Cooper’s own 62 lb — see what the spec sheets get wrong. The figures on this page come from a source that matches the manufacturer.
What they cost
Tire
LT285/70R17, per tire
Read
BFGoodrich KM3
$339.99
11 Sep 2026
Cooper Discoverer STT Pro
Not tracked
—
The STT Pro is not in the price tracker.
Which matters for your use case
If you are buying on published depth and mass, the Cooper is listed ahead in every matched size.
If you want a manufacturer to commit to measurable performance claims, only BFGoodrich does.
If you run 33×12.50R17, only the KM3 is listed in that size.
If you need snow certification or a treadwear warranty, neither provides one.
Model pages and data
BFGoodrich KM3 · specification database
Related
KM3 vs Baja Boss M/T · what the spec sheets get wrong · sidewall plies and ply rating · budget mud tires · KM3 vs Trail Grappler
Sources
Tire Rack, Cooper Discoverer STT Pro description and warranty (tirerack.com) · BFGoodrich, Mud-Terrain T/A KM3 (bfgoodrichtires.com), both read 17 September 2026 · Tire Size (tiresize.com), model specification pages, read 17 September 2026 · Mud Tires price tracker.
How these figures are gathered and what we refuse to estimate: our method.