The Donnelly EMP 700×38 tire is designed for aggressive mixed-terrain riding, striking a balance between speed, traction, and durability. It is a tubeless-ready gravel tire with deep center knobs and pronounced shoulder tread. This review provides a detailed, technical assessment of its performance characteristics, installation procedure, common setup issues, and optimization strategies.

Tools Required

• Tire levers
• Tubeless tire sealant
• Floor pump or compressor
• Tubeless-compatible rim tape
• Valve core remover
• Torque wrench (for axle reinstallations)

Installation Process of Donnelly EMP 700×38

Installing the EMP 700×38 tires requires attention to bead alignment, tubeless sealing, and rim compatibility. The tire’s casing is supple yet supportive, which aids in the mounting process but demands precise technique to avoid leakage or burping.

Start by confirming the rim is tubeless-ready. Apply tubeless tape if the rim isn’t pre-taped. Insert a tubeless valve and secure it. Mount one side of the tire bead, then add sealant into the casing before fully seating the second bead. Use a floor pump or compressor to rapidly seat the bead—compression must be evenly distributed around the rim to prevent wobbles. Spin and shake the wheel to distribute sealant before checking for any audible leaks or bead separations. Reinstall the wheel onto the bike, torquing the axle to the manufacturer’s specifications.

Adjustment and Bead Seating Precision

Proper bead seating is vital for consistent pressure retention and traction. The EMP’s bead locks securely onto most modern hookless and clincher rims. However, improper inflation can lead to partial seating. Inspect sidewall conformity by rotating the wheel and observing for any vertical run-out or side bulging. If detected, deflate the tire, reposition it, and reinflate while manipulating the sidewalls by hand to assist alignment.

Pressure tuning is equally critical. Donnelly recommends starting at 35–45 psi, adjusting based on rider weight and terrain type. For rougher surfaces, lowering the pressure to around 30 psi can enhance grip, but riders must ensure the tire doesn’t bottom out on the rim under load.

Maintenance and Durability Checks

Routine maintenance helps preserve tread life and tubeless integrity. Every few weeks, inspect the tire for embedded debris or slicing. The EMP’s tread features a relatively open design, making it easier to remove stuck gravel or thorns. Use a damp cloth to clean off dried mud or sealant. Replenish sealant every 2–3 months to maintain puncture protection.

Sidewall cuts are rare due to the reinforced casing, but always check the transition zone between tread and sidewall after each long ride. Monitor tread wear by observing the central knobs—if they begin rounding off or showing surface cracking, it’s time to rotate or replace the tire.

Troubleshooting Common Set-Up Issues

Tubeless leaks at the sidewall junction may occur if insufficient sealant is used or if the tire was mounted dry. Removing the tire and reapplying a liberal amount of sealant usually resolves the issue.

Poor bead seating might result from using a hand pump instead of a compressor. If a compressor is unavailable, a CO₂ inflator can temporarily substitute to generate a strong inflation burst. Avoid excessive pressure over 60 psi, which may damage the casing or the rim.

Burping under lateral loads—common in low-pressure scenarios—usually stems from under-inflation or loose bead engagement. Re-seat the tire with added sealant and slightly increase the pressure to minimize sidewall flex.

Customization and Performance Optimization

The EMP 700×38 can be customized for racing or endurance use through pressure and wheel choice. For riders focusing on speed over dry gravel, pairing with a lightweight carbon wheelset and inflating to 45 psi can reduce rolling resistance. For wet, technical courses, a pressure reduction to 30–32 psi increases footprint and improves grip.

Tubeless sealant selection can also affect performance. Latex-based sealants work best with this tire due to fast sealing properties, especially in colder environments. Adding tire inserts such as CushCore Gravel can prevent rim strikes and allow lower pressures without sacrificing security.

Compatibility with Drivetrain and Frame

The 700x38c size is compatible with most modern gravel and endurance frames that support up to 40mm clearance. Check chainstay and fork arch tolerances before installation. For riders using 1x drivetrains, the larger volume and traction of this tire pair well with wide-range rear cassettes, particularly on steep or loose climbs.

EMP tires are best matched with rims 21–25mm internal width. Wider rims increase tire volume and stability, while narrower rims may pinch the casing and degrade sidewall integrity.

Comparison with Similar Tires

Compared to other gravel tires like the WTB Resolute 700×42 and the Panaracer GravelKing SK 700×38, the EMP offers a more aggressive tread and superior cornering performance. The Resolute provides better flotation in muddy conditions due to its width, but it lacks the sharp knob definition found on the EMP. Meanwhile, the GravelKing SK is faster on pavement but underperforms on soft or loose ground.

The EMP 700×38 shines in mixed terrain where varied grip is essential. It offers a compromise between the speed of semi-slicks and the traction of true knobbies, making it a strong choice for riders who transition between dirt, gravel, and tarmac frequently.

Frequently Asked Questions

1. Is the Donnelly EMP 700×38 suitable for tubeless use?
Yes, it is tubeless-ready and performs best when mounted with sealant on compatible rims.

2. Can I use the EMP 700×38 on paved roads?
Yes, though it is optimized for off-road traction, it remains efficient on pavement due to the tightly spaced center tread.

3. What’s the recommended tire pressure range?
Start with 35–45 psi, adjusting based on rider weight and terrain. Lower for softer terrain, higher for pavement.

4. How often should I add tubeless sealant?
Check every 2–3 months and top off if levels are low. Frequency increases in hot or dry climates.

5. What terrain is best suited for the EMP 700×38?
It excels on gravel, hardpack, light mud, and broken pavement. It’s not ideal for deep mud or loose sand.

6. How does the EMP compare in terms of rolling resistance?
It rolls slightly slower than semi-slicks but outperforms them in grip and control on variable surfaces.

Conclusion

The Donnelly EMP 700×38 is a purpose-built, high-traction gravel tire that offers confident handling and durability across a range of terrains. Its balance of aggressive tread and reliable tubeless performance makes it a valuable addition to any rider’s quiver, especially those seeking versatility for adventurous routes. With proper installation and maintenance, it delivers consistent, high-level performance for gravel racing, bikepacking, and long-distance mixed-terrain cycling.