2021 Peterbilt 389 Tire Size & Pressure

Quick answer

• OEM Tire Sizes: Steer Axle: 11R22.5, 295/75R22.5; Drive Axle: 11R22.5, 295/75R22.5
• Recommended Cold Tire Pressure: Varies significantly based on load and tire type. Refer to the vehicle's tire placard for specific recommendations.
• Bolt Pattern: 10-hole, 285.75mm bolt circle (hub-piloted)
• Wheel Size: 22.5 x 8.25 inches (typically)
• Load Index/Speed Rating: Varies greatly depending on specific tire. Consult tire sidewall for details.
• Spare Tire Size: Varies. Often unmounted or a used take-off.
• TPMS Frequency: Not typically equipped with TPMS in the same manner as light-duty vehicles.

Tire Sizes by Trim

For the 2021 Peterbilt 389, "trim" often relates more to vocation and axle configuration than distinct passenger car-like trims. Tire sizes are primarily chosen based on the intended use, gross vehicle weight rating (GVWR), and axle GAWRs.

While these are common, Peterbilt offers a wide range of factory-installed tire options to suit various applications, including different tread patterns for highway, regional, or vocational use.

Recommended Replacement Tires

When replacing tires on a Peterbilt 389, selecting the right tire is crucial for safety, fuel efficiency, and longevity. Consider these popular options:

• Michelin X Line Energy Z (Steer) / D (Drive) - Premium Tier: Known for excellent fuel economy and long tread life, ideal for long-haul applications. Expect a higher price point.
• Goodyear Fuel Max S (Steer) / D (Drive) - Mid-Premium Tier: A strong contender for fuel efficiency with good mileage and traction, offering a balance of performance and value.
• Bridgestone R283A Ecopia (Steer) / M713 Ecopia (Drive) - Mid-Premium Tier: Designed for fuel efficiency and durability, often a popular choice for fleets looking to optimize operating costs.
• Cooper PRO Series (Steer & Drive options) - Mid-Tier: Offers a more budget-friendly option without sacrificing too much on performance, suitable for various applications.

Always ensure the replacement tires meet or exceed the load and speed requirements of the vehicle as specified on the tire placard.

When to Inflate to Max Load PSI

For heavy-duty trucks like the 2021 Peterbilt 389, tire pressure is not a set value but rather a dynamic parameter that depends heavily on the actual load being carried. You should never simply inflate to the "max PSI" molded on the tire sidewall unless you are consistently carrying the absolute maximum allowable load for that tire.

Instead, always refer to the vehicle's door placard (or often, a separate decal on the frame rail or in the glove box for heavy trucks) for recommended cold inflation pressures. These placards usually provide pressure recommendations based on the Gross Axle Weight Ratings (GAWR).

To determine the correct tire pressure:

1. Weigh your truck: Get accurate axle weights (steer, drive, trailer if applicable) when loaded as you would typically operate it.
2. Consult a tire manufacturer's load/inflation table: Tire manufacturers provide detailed charts that correlate tire size, ply rating/load range, and inflation pressure with carrying capacity. Based on your actual axle weights, find the minimum pressure required to safely support that load.
3. Add a safety margin: It