The Donnelly EMP 700×38 is a tubeless-ready gravel tire designed for aggressive terrain, offering exceptional traction and durability. With its tightly packed center tread and prominent side knobs, this model is ideal for riders who need a tire that can handle everything from rocky trails to loose gravel. This guide covers everything you need to install, adjust, maintain, and optimize the EMP 700×38 tires on your gravel bike.

Tools Required

• Tire levers
• Tubeless valve stems (if running tubeless)
• Tubeless sealant
• Floor pump or air compressor
• Bead lubricant or soapy water
• Clean rags
• Digital tire pressure gauge

Tire Overview and Design Specifics

The EMP 700×38 is named after Emporia, Kansas, home of the iconic gravel race Unbound Gravel. Donnelly designed this model for high-speed control and cornering stability. The center tread is composed of densely spaced knobs for reduced rolling resistance, while the side knobs are spaced to enhance grip on loose corners.

Its 38mm width offers a balance between speed and comfort. The tubeless-ready casing supports lower pressure riding without risking pinch flats. This makes it suitable for long-distance gravel adventures where comfort, traction, and reliability are critical.

Preparing the Rim for Tubeless Setup

Before installation, ensure the rim is tubeless compatible and prepped with a tubeless rim tape. The tape should be tightly sealed across the spoke holes, with no air gaps. Press a tubeless valve firmly into the drilled hole, ensuring the rubber base creates a tight seal against the rim bed. Secure it with the locknut from the outside.

Inspect the rim to confirm cleanliness and proper sealing. Any dust or old sealant residue should be thoroughly wiped away before proceeding.

Mounting the EMP 700×38 Tire

Begin by aligning the tire branding with the valve stem for visual consistency and easier location of leaks or punctures during rides. Mount one side of the tire bead onto the rim by hand, starting opposite the valve and working your way around.

Once one side is seated, add the recommended volume of tubeless sealant inside the tire. Insert the second bead into the rim starting at the valve and progressing in both directions. The final section near the valve may be tight; use tire levers cautiously to avoid damaging the bead.

Spray soapy water around the bead and sidewalls. This helps the tire seat more easily and reveals any air leaks once inflated.

Inflating and Seating the Tire Bead

Using a high-volume floor pump or compressor, inflate the tire quickly to 40–50 psi to snap the bead into place. You should hear multiple loud pops as the bead seats correctly around the rim.

Inspect the entire circumference of the tire. A consistent inner line—called the bead line—should be visible just above the rim edge. If the bead line disappears at any point, deflate and reseat that section before reinflating.

Once properly seated, spin the wheel and bounce it gently to help distribute the sealant evenly.

Tire Pressure and Performance Tuning

Tire pressure significantly affects performance. For the EMP 700×38, most riders will find optimal pressure between 30–45 psi, depending on rider weight, terrain, and riding style.

Lower pressures (30–35 psi) offer better traction and comfort on rough terrain. Higher pressures (40–45 psi) reduce rolling resistance for faster gravel or mixed surfaces. Always test tire pressure before each ride using a reliable gauge.

Over time, adjust based on ride feel, but avoid going below the manufacturer’s minimum recommended pressure.

Maintenance and Long-Term Care

Tubeless tires require periodic maintenance. Every few weeks, inspect for punctures, sidewall abrasions, and sealant levels.

Sealant typically dries out within 2–6 months depending on climate and usage. Remove the tire and add fresh sealant as needed. Reinspect the bead for integrity and ensure the valve is not clogged or leaking.

If the tire casing begins to show signs of aging, such as severe cuts or weakened sidewalls, replace it promptly.

Troubleshooting Common Installation Issues

Bead won’t seat: Use more soapy water and a compressor. In some cases, removing the valve core briefly allows more air to enter quickly for an initial bead lock.

Air leak at valve: Check that the valve is snug and seated against the rim tape. Use a valve core tool to retighten or replace the valve if needed.

Slow air loss: Spin and shake the wheel to distribute sealant. If leaks persist, inspect for bead gaps or casing damage. Add more sealant or reinstall tire.

Customization and Performance Optimization

To tailor the EMP 700×38 for varied terrain:

• Use lightweight sealant for race-day speed and standard sealant for durability.
• Pair with wider rims (21–25mm internal width) for a more stable tire profile and increased air volume.
• Combine with lower rolling-resistance front tires for speed-biased setups or with a matching rear EMP for aggressive grip and control.

Consider rotating tires every 1,000–1,500 miles to even out tread wear and extend service life.

Compatibility With Other Drivetrain and Wheel Systems

The EMP 700×38 fits most modern gravel bikes using 700c wheels with sufficient clearance. Check your frame’s maximum tire clearance, especially if equipped with fenders or integrated mounts.

It’s compatible with both hookless and hooked tubeless rims, though always confirm the manufacturer’s pressure limits for hookless applications. For tube users, a standard 700×35–43c tube works well.

This tire integrates well with 1x and 2x drivetrains. Riders using wide-range cassettes or compact cranksets will benefit from the added grip and control on steep or loose inclines.

Comparing the EMP 700×38 to Similar Gravel Tires

Compared to the Donnelly X’Plor MSO 700×40, the EMP offers superior side grip and better high-speed cornering. The MSO leans more toward mixed surface use, while the EMP thrives in rougher conditions.

When compared to the WTB Riddler 700×37, the EMP has more pronounced tread for improved traction but at the cost of slightly higher rolling resistance. The Riddler suits faster, drier conditions, whereas the EMP excels in technical gravel and soft surfaces.

For riders seeking maximum speed, the Panaracer GravelKing SK 700×38 is a popular alternative with lower rolling resistance but less aggressive tread.

Final Thoughts

Installing the Donnelly EMP 700×38 tires is a straightforward process when using the right techniques and tools. Their robust tubeless design, grippy tread pattern, and dependable casing make them a top choice for serious gravel riders tackling challenging terrain.

Regular maintenance, proper inflation, and thoughtful component pairing will help you maximize performance and extend the life of these tires.