Cooper Discoverer Radial STT TEK3 Tire Review & Rating

Cooper has several models of all-terrain and off-road tires in their lineup, but the Discoverer Radial STT TEK3 is their first rock climbing heavy duty off road tire. Designed for pickups, SUV’s and other off-road vehicles, the TEK3 literally takes you through anything and everything you could want to go through.

The power of this tire is the Armor-TEK3 carcass that Cooper has designed for the tread. It’s constructed with two radial polyester body plies and one angled polyester body ply. The result is outstanding protection against bruising, chips, punctures and impact breaks. It’s built to withstand maximum abuse, and the many reviews from other drivers on this tire confirm how well it works.

Cooper Discoverer Radial STT TEK3 Tire Review

The aggressive tread design on the Discoverer STT goes further down the sidewall to enhance traction on softer surfaces such as sand, dirt, snow and more, while also creating more grip when climbing rocks. Keeping stones out of the tread pattern is made easier with the stone ejector rib that extends down from the center lugs to the buttress blocks.

The Discoverer STT TEK3 also has a rim flange protector to prevent damage to your expensive wheels when driving off-road. Cooper provides the option of getting the tire in your choice of white or black lettering on the sidewall depending on the size you select. You’ll find this model in 16-20 inch sizes as well.


  • Perform very well on rocks, mud, sand, gravel, dirt, snow and trail   
  • Outstanding resistance to chips, breaks and bruising   
  • Among the most quiet tires in this class   
  • Attractive tread design   


  • Expensive 

Overall Thoughts

This is Cooper’s first venture into the rock crawling heavy duty off-road tire market, and they have come out with a huge success in the STT TEK3. This tire is flat out awesome in delivering high performance off-road enjoyment. Regardless of the terrain, the tire goes through it.

The Armor-Tek3 prevents punctures, chips, breaks and bruising, and does its job very well. Beyond that, the tire is nearly as quiet as an A/T model. Many reviews from other drivers have mentioned this as well. Overall, this is a fun tire to drive on the trails or anywhere else you can think of taking it.

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What Vehicles Will The Cooper STT TEK3 Fit?

(This is not a complete list of ALL vehicles this tire will fit)

  • Chevrolet K1500, Silverado, K2500, Colorado   
  • Dodge Ram, Dakota   
  • Ford F-350, F-250, F-150, Ranger   
  • GMC K1500, Yukon, Canyon, Sierra   
  • Jeep Wrangler   
  • Nissan Titan   
  • Toyota Landcruiser, Tundra, Tacoma, 4Runner   

Tire Sizes


LT225/75R-16/E1 115Q
LT235/85R-16/E1 120Q
LT245/75R-16/E1 120Q
LT255/70R-16/C1 108Q
LT265/75R-16/E1 123Q


LT245/70R-17/E1 119Q
LT265/70R-17/E1 121Q
LT295/70R-17/D1 121Q
33X1250R17LT/D2 114Q


LT275/70R-18/E1 125Q
LT305/60R-18/E2 121Q
LT325/60R-18/E2 121N
LT325/65R-18/E2 127N


33X1250R20LT/E2 114Q
35X1250R20LT/E2 121Q

Price Range

Prices on the TEK3 range from approximately $196 and up. You may also find occasional rebates, discounts, coupons and special offers on this tire.

Click Here To Find The Lowest Prices On All Cooper Discoverer Radial STT TEK3 Sizes


Cooper includes a limited warranty on the TEK3, which includes a first 2/32 inch of wear on the tire’s uniformity.

Materials and workmanship are covered for 5 years and include free tire replacement during the first 2/32 inch of wear. Cooper then prorates out the amount for the remaining time period or down to the final 2/32 inch of tread depth.

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