Cooper Discoverer AT3 4S All‑Terrain Tire
Built for everyday driving and weekend adventures, the Cooper Discoverer AT3 4S delivers a quiet, controlled ride on pavement with confident traction when weather turns or roads end. This all-terrain design pairs a cold-weather compound with full-depth siping to maintain grip as temperatures drop, and it carries the Three-Peak Mountain Snowflake symbol for certified severe-snow performance. Drivers choose the AT3 4S for its balanced manners, with stable handling, strong wet braking, and reliable bite on dirt and light trails, without the excess noise or harshness of more aggressive off-road tread patterns. Select your size to check availability and pricing.
Key Features & Technology
The Discoverer AT3 4S blends a silica-enhanced, cold-weather compound with an all-terrain tread pattern to keep traction consistent across seasons. Full-depth sipes help the blocks stay flexible for wet braking and snow grip, while the optimized block geometry lowers pattern noise for a calmer highway ride. In snowy conditions, Cooper's Snow Groove technology creates biting edges that pack and hold snow in the tread, which boosts snow-on-snow friction. A robust casing and reinforced tread elements add durability on gravel and rough county roads, yet the tire remains tuned for comfort and even wear in daily use.
On‑Road Comfort, Handling & Wet Grip
On pavement, the AT3 4S feels composed and confident. The tread's variable pitch helps keep road noise in check for an all-terrain, and the center ribs support straight-line stability and clear steering response. A high-silica compound and dense siping move water away to maintain contact in the rain, which supports surefooted braking and cornering. If you are upgrading from a highway all-season, expect a touch more tread presence at speed, but compared with a more aggressive A/T you will notice a quieter cabin and a more refined ride.
Snow Traction & Light Off‑Road Capability
Certified with the Three-Peak Mountain Snowflake, 3PMSF, the AT3 4S stays pliable in cold temperatures and keeps its bite in packed snow. Snow Groove technology and full-depth sipes help it claw through light to moderate winter conditions. On dirt, gravel, and forest-service roads, the staggered shoulder elements and open channels provide dependable traction without feeling heavy or harsh. For deep mud, heavy rock work, or frequent towing at high loads, consider a more specialized all-terrain in the Cooper lineup that is built for those demands.
Sizes, Fitment & Load Ratings
The Discoverer AT3 4S comes in a wide range of P-metric and XL sizes for popular crossovers, SUVs, and half-ton pickups. Always match your vehicle's OE tire size, load index, and speed rating on the driver-door placard. Most sizes are Standard Load, SL, or Extra Load, XL, rather than heavy-duty LT constructions, which suits daily driving and occasional adventure. If you tow or haul near max capacity, verify load requirements before purchase, rotate regularly, and maintain the vehicle-recommended pressures to support even wear and consistent traction.
Popular sizes for the AT3 4S
Top-searched sizes include 275/60R20, 265/70R17, and 275/55R20, common fits for late-model trucks and SUVs. Availability can vary by season and region, and some wheel diameters may offer multiple load options. Use your vehicle's door-jamb label or owner's manual to confirm exact size and load index, then filter by that specification to view in-stock AT3 4S listings. If you do not see your size, our team can suggest a comparable fit or advise on the correct variant within the Discoverer line based on your payload and driving mix.
Load and ply rating explained
Most AT3 4S sizes are P-metric SL, Standard Load, or XL, Extra Load. Instead of old-school ply counts, focus on the load index number printed on the sidewall, it directly indicates how much weight each tire can support. XL sizes offer a higher maximum load and may ride slightly firmer at the same pressure. If your use involves frequent towing, payloads near the vehicle's limits, or rougher terrain at lower pressures, verify your required load index and consider whether a heavy-duty LT construction in a different model is a better match, and when in doubt follow the vehicle placard.
Tread depth and recommended pressure
New tread depth for the AT3 4S varies by size, so check the specs for your selected fitment. For daily driving, maintain the tire pressure listed on your vehicle's door-jamb label, not the sidewall maximum. Rotate every 5,000 to 8,000 miles, or per your vehicle's schedule, to encourage even wear. Legally, tires are worn out at 2/32 in., but for winter performance you should replace around 4/32 to 5/32 in., since snow and slush traction depends heavily on depth and siping.
Price, Warranty & Value
Pricing for the Discoverer AT3 4S varies by size and load rating. Expect mid-range pricing that reflects its blend of on-road refinement and year-round capability, including 3PMSF winter certification. Cooper backs the AT3 4S with a limited warranty, and coverage details, including any treadwear protections, depend on size and use, with periodic promotions or rebates available. Consider total value, since strong wet and snow performance, quiet highway manners for an A/T, and broad size coverage make it a smart pick for mixed driving.
Availability and replacement status
In some markets and sizes, the Discoverer AT3 4S is being phased out in favor of the Cooper Discoverer Road+Trail AT, which builds on similar all-weather goals while retaining 3PMSF certification. Many AT3 4S sizes are still in circulation, and inventory varies by region. If your preferred size is limited or out of stock, we can confirm current availability or suggest the closest in-line successor to match your driving needs. You will see live stock and pricing after selecting your exact size and load index.
AT3 4S vs. AT3 LT and XLT
All three tires share an all-terrain mission, but they target different uses. The AT3 4S prioritizes everyday comfort, wet grip, and winter readiness in P-metric and XL sizes, ideal for commuters, family road trips, and light trail use. AT3 LT and XLT step up with LT-metric constructions, a heavier-duty casing, and more aggressive features for towing, hauling, and rough off-road surfaces. If you mostly drive on pavement with occasional dirt or snow, the AT3 4S fits best, while regular heavy loads or air-down off-road use call for an LT-spec alternative within the family.
