2018 Kenworth T680 Tire Size, Pressure & Wheel Specs

For commercial operators and fleet managers, keeping a 2018 Kenworth T680 properly rubbered is critical for fuel efficiency, safety, and maximizing uptime. The T680 is a flagship Class 8 aerodynamic tractor, meaning tire selection directly impacts its bottom-line performance.

Below is your comprehensive ASE-certified guide to the tire sizes, pressures, and wheel specifications for the 2018 Kenworth T680.

Quick answer: 2018 Kenworth T680 Tire Specs

• OEM tire size: 295/75R22.5 (Steer & Drive) is the most common aerodynamic spec, with 11R22.5 and 285/75R24.5 available depending on the chassis build.
• Recommended cold tire pressure (door placard): Typically 105–110 PSI (Front/Steer) and 100 PSI (Rear/Drive), though this varies strictly by the GAWR on your specific VIN placard.
• Bolt pattern: 10x285.75mm (Hub-piloted).
• Wheel size: 22.5" x 8.25" (Standard) or 24.5" x 8.25".
• Load index/Speed rating: Load Range G (14-ply) or Load Range H (16-ply). Speed rating L (75 mph) or M (81 mph).
• Spare tire size: Full-size matching spare (if equipped; many fleets opt out of onboard spares to save weight).
• TPMS frequency: 433 MHz (commonly Bendix SmarTire systems).

Tire sizes by application

Class 8 trucks like the Kenworth T680 don't use "trims" in the traditional passenger-car sense. Instead, tire sizes are dictated by the application (Linehaul, Regional, or Heavy Haul) and wheel specification.

Note: Always verify the steer axle weight rating before stepping down in tire size or ply rating.

Recommended replacement tires

When replacing tires on the T680, you need low rolling resistance for the steer axle and high-traction, long-life rubber for the drives.

1. Michelin X Line Energy Z (Steer) / D (Drive) – Premium Tier The industry standard for linehaul fuel efficiency. These SmartWay-verified tires offer exceptional mileage and predictable handling.
2. Bridgestone R213 Ecopia (Steer) / G3000 (Drive) – Premium Tier A highly durable combination that fights irregular wear while maintaining low rolling resistance. Excellent casing for retreading.
3. Yokohama 114R (Steer) / 712L (Drive) – Mid-Tier A reliable, cost-effective alternative for fleets looking to balance upfront cost with long-term performance and retreadability.
4. Goodyear Endurance LHS / LHD – Premium Tier Designed for long miles to removal, providing great lateral stability for drivers tackling cross-country routes.

When to inflate to max load psi

Because the 2018 Kenworth T680 is a heavy-duty commercial truck, tire pressure is inextricably linked to axle loads.

You should inflate your tires to the maximum cold PSI listed on the tire sidewall (typically 110 to 120 PSI for Load Range G or H) only when your actual scaled axle weight requires it according to the tire manufacturer's load and inflation tables.

For example, a steer axle rated for 13,200 lbs running 295/75R22.5 tires will require approximately 110 PSI to safely carry the load. Running 120 PSI on an empty trailer or light load will lead to center-tread wear, a harsh ride, and suspension fatigue. Always match your pressure to your typical loaded state.

Lug nut torque & pattern

The 2018 Kenworth T680 uses industry-standard hub-piloted wheels.

• Bolt Pattern: 10 on 285.75 mm
• Hardware: M22 x 1.5 studs with two-piece flange nuts
• Torque Specification: 450 to 500 ft-lbs.
• Tightening Sequence: Always use a standard 10-lug star pattern (e.g., 1-6-3-8-5-10-2-7-4-9) to ensure the wheel seats squarely against the hub.

Tech Tip: Hub-piloted wheels must be re-torqued after the first 50 to 100 miles of operation following a wheel removal.

Common tire issues for this vehicle

• Irregular Steer Tire Wear: The T680's aerodynamic stance can sometimes mask alignment issues. River wear (edge wear) or cupping on the steer tires usually indicates a need for a three-axle alignment, worn kingpins, or worn shock absorbers.
• Drive Tire Heel/Toe Wear: Often caused by mismatched tire diameters in dual assemblies or aggressive braking habits. Always ensure duals are matched within 1/4-inch in circumference.
• TPMS Sensor Failures: The internal wheel-mounted sensors on commercial TPMS systems can be damaged by careless tire mounting/dismounting or battery death (batteries typically last 5-7 years, putting 2018 models right in the failure window).

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