The Donnelly EMP gravel tire gets its name from the airport code for Emporia, Kansas, arguably the place that put gravel racing on the map. As the most aggressive gravel tread in the Donnelly's line-up, the EMP is ready to rail miles of gravel and mix it on the trail.

Donnelly EMP Highlights

  • Tight tread block pattern and aggressive shoulder lugs offer excellent grip.
  • Soft rubber compound rides fast on road and gravel with minimal reverb.
  • Integrated puncture protection belt under the tread is hardly noticeable in weight.
  • Reinforced tubeless casing wears well and prevents sidewall cuts.
  • Excellent braking traction on quick and bombed-out gravel descents.
  • The larger size is great for shredding single track and gravel quickly.
  • Size: 700x45 (tested) 700x35
  • Weight: 537 grams
  • Price:$60.00

Rating: 4.5/5.0

Gravel is pretty predictable, right? Long roads covered in...gravel, and then the fastest person wins the ride/race, and we all eat burritos and drink beer. Wrong! Well, the drinking and eating part, yes. But all gravel roads are not equal. Those who frequent rides Dirty Kanza will need a different tire than those racing the Hilly Billy Roubaix or KeyStone Gravel. For those that require both grip and fast-rolling on the hard-packed surface, the EMP from Donnelly could be your best bet.

The Tread

The tread on the Donnelly EMP is something you would expect to see on a World Cup cross country tire: fast-rolling and able to grip dry terrain. The tightly-spaced knobs allow rolls quickly and bites when climbing or sprinting.

The tread pattern offers above-average traction with surprisingly low rolling resistance. As you roll this tire on its side, the combination of a more open tread pattern and aggressive side knobs offer incredible cornering capabilities. Beefy side-knobs take a page from the equally combative BOS cyclocross tire (named for wintry Boston 'cross conditions) and provides predictable cornering control. The center tread design borrows slightly from Donnelly's MSO which, to date, was considered the most aggressive in their ever-expanding gravel stable (and a favorite of Kanza racers.)

Since the EMP is a Dirty Kanza terrain style tire, the tread excels on both fire road drag racing and hard-packed trails. Weighing just 537 grams, the EMP is respectably light, considering the puncture protection belt and generous knobs.

Setup and inflation

The Donnelly EMP mount quickly, and the bead was tight enough to inflate with a floor pump. Paired with my FSA AGX carbon wheels with a 26.1 mm wide internal these tires are massive. They fit cleanly on Salsa Journeyman and used as an exclusive front tire on my Specialized Crux. The secure fit is worth noting, this secure fit is standard amongst most mountain tires but is uncommon with gravel and cyclocross tires.

The Ride:

My first rides on the EMP were on the road and eventually led to the gravel promised land. On the pavement and blown out country road near my house the EMP offers little difference to the average gravel tire. The ride is smooth and with the large volume - very comfortable but nothing groundbreaking. When I rolled from the pavement to the gravel though, the EMP felt great, confident in the terrain and able to turn with ease. On larger chunks of gravel and rock, the tire floats, keeping the rider comfortable and less strain on the lower back and arms. I can see this being a considerable advantage on long days and race where the rider attrition is the limiting factor of finishing. The side knobs dig into the dry earth when emersed but keep the momentum rolling forward and steering predictable.

On dry and buff singletrack the EMP rolls fast and feels like an XC dry race tire. The star of the EMP is the cornering knobs and the tightly spaced center tread - these are paramount in making the tire fast-rolling but controllable when the rider comes across deep sand and mud.

The EMPs only weakness is the thick and soupy mud that can pop up on singletrack visits. Though the EMP has no notions of being a mud hero, it is nice to know that if the precipitation comes falling, you can still stay at the same pace. When I encountered mud, I noticed the tightly spaced knobs do not shed as quickly as its PDX brethren. The dirt tends to build up until you hit a paved sector or a full-on water emersion. Mud accumulation is not uncommon in gravel-specific tires but is the only thing that holds the EMP back from being a genuinely all-conditions tire.


The Donnelly EMP features an excellent, fast-rolling tread with options the will fit a CX frame, gravel, and monster-cross. If I had to pick a target market, I would say the EMP is for riders that want to go fast without anything to hold them back. The EMPs puncture protection is top-notch, and I've yet to get a flat on my review samples. Keep an eye on the forecast if you plan on riding in the dirt, but when on the road and gravel the EMP is solid performer, rain or shine. If you plan on racing the Dirty Kanza or an event like it put the EMP on your shortlist and get ready for a fast ride.

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