New Balance Fresh Foam X Hierro Mid GTX review

Don't sleep on the Hierro Mid GTX if you are after the following:

• an uber-soft, well-cushioned hiking boot for light and moderate hikes
• a lightweight running shoe-based boot for the trails
• a stylish and versatile boot that feels at home on the trail and in the streets

Skip this New Balance boot if you need a more technical option for off-trail adventures and challenging multi-day trips.

For these scenarios, we recommend looking into the Salomon X Ultra 4 Mid GTX, the La Sportiva Ultra Raptor II Mid GTX, or even more rugged and expensive backpacking boots.

If you ever tried New Balance's Fresh Foam running shoes, you will find the familiar cushioned goodness in this mid-cut Fresh Foam X Hierro.

The boot packs a generous heel stack of 35.4 mm which is on par with the category average. However, the Fresh Foam X's cushy nature makes it feel even thicker than that! The foam maintains excellent impact protection for hours of hiking.

The balls of our feet also felt pampered thanks to the above-average forefoot stack of 25.3 mm. The boot's thick-foamed platform devoured every bump, root, and rock we stepped on during the wear test keeping us reasonably isolated from the trail.

New Balance built the Hierro Mid on the basis of the Hierro v7 trail running shoe which explains similarities in their stack heights and heel-to-toe drops.

Based on our caliper measurements, the Hierro Mid's drop comes in at 10.1 mm which is slightly higher than the brand's stated 8 mm (granted, NB claims their drop measurements to be approximate due to variances in the development and manufacturing process).

A 10-mm offset is slightly lower than the average of hiking boots but should feel nice and balanced for most hikers. It puts the heel in a moderately elevated position to lessen the strain on the Achilles.

We are happy to report that New Balance is not joking about the cushioning softness of the Hierro Mid GTX. Its Fresh Foam X midsole showed a record-breakingly low reading on our Shore A durometer!

At only 14.7 HA, it turned out to be the softest hiking boot midsole in our lab to date! Followed by the Boost foam of the Adidas Terrex Free Hiker 2 (15.4 HA).

The Hierro Mid essentially feels like a plush running shoe underfoot. Our steps felt well-cushioned, smooth, and effortless, even on hard-packed terrain. Not to mention that the post-hike fatigue felt as minimal as it can be.

Unfortunately, the boot's Fresh Foam X midsole comes with a drawback - it loses nearly half of its softness in cold weather.

To mimic chilly conditions, we kept the boot in the freezer for 20 minutes and repeated the durometer measurement. The latter showed 21.0 HA which is 43% firmer than the one we took at room temperature.

So if you're camping overnight and the temperature drops to 30°F (0°C) or below, expect the Hierro Mid to feel notably firmer than the day before. It will take some warming up to break it back in.

But the good news is that even in its frozen state, the Hierro Mid feels significantly plusher than the average hiking boot at room temperature.

At 4.7 mm, the boot's insole turned out to be thicker than that of the Hierro shoe (3.0 mm) but thinner than the average of hiking boot insoles.

Trying the Hierro Mid GTX in a standard D medium width felt exactly on point for our medium-width feet. But how does it compare to the other hiking boots? We poured a gel mold of its toebox to find out.

When the replica was ready, we measured its widest part with a digital caliper. At 92.6 mm, it turned out to be a tad narrower than average but not enough to tag it as narrow.

And yet, folks with wider feet will be glad to know that the NB Hierro Mid GTX is also available in wide and extra wide options.

With a standard width of 70.4 mm near the big toe, the boot's toebox is very mildly tapered. It offers sufficient wiggle room and doesn't squeeze the toes.

The boot's vertical space is slightly limited because of the dense toebox leather. At 26.1 mm, its toebox height is a couple of milimeters lower than average.

The low-cut Hierro v7 was a rather stable shoe already but the Hierro Mid GTX took it further by adding a tall and well-padded ankle collar, thick leather overlays, and other design tweaks to turn it into an actual hiking boot. It's more than just a running shoe with a higher ankle cut!

The boot offers excellent side-to-side containment on uneven terrain and doesn't let the foot buckle under the backpack load.

Thanks to its sturdier upper design, the boot has significantly higher torsional rigidity than its low-cut counterpart.

Assessing its stiffness on a 1-5 scale, we easily gave it the highest score of 5 because the boot refused to twist even one bit!

The Hierro Mid's heel counter strikes a fine balance between flexibility and stiffness delivering a secure lockdown with some degree of ankle mobility for comfortable descending.

We rated he boot's heel counter stiffness with a middle-ground score of 3 in our push-and-squeeze test.

There is a lot of visual bulk to the New Balance Fresh Foam X Hierro Mid GTX but in reality, it is not as chunky as some of the other hiking boots we've tested (like the Hoka Anacapa for example).

Applying our caliper to the widest part of the boot's midsole in the forefoot returned 109.3 mm. Even though it is slightly narrower than average, it is not a narrow platform by any means.

Featuring outriggers on both lateral and medial side of the forefoot, the Hierro Mid never allowed our feet to buckle (or even feel like it was about to).

The wide and square-shaped heel is another cornerstone of the boot's stability. It kept our landings surefooted no matter how bumpy or rocky the trail got.

As a running shoe sibling, the Hierro Mid GTX managed to keep some of its smaller brother's flexibility in the forefoot. Even though its thick synthetic and leather overlays detracted from the pliability, it still proved to be bendier than most other hikig boots.

According to our force gauge, it took 40% less force to bend this NB boot to a 90-degree angle compared to the average hiking boot.

The added flexibility made the Hierro Mid GTX feel more comfortable and sneaker-like as well as more suitable for urban settings.

Gladly, the boot remained relatively flexible in chilly conditions. Repeating the force gauge measurement after a 20-minute freezer session, the Hierro Mid only got 16% stiffer.

Despite its beefy silhouette, the NB Hierro Mid clocks in at only 13.7 oz (388g). About 5 ounces lighter than the average hiking boot, it feels incredibly easy and non-taxing on foot. Amazing platform-to-weight ratio!

As a waterproof boot with a Gore-Tex membrane, solid leather overlays, and a very tightly-woven upper textile, the Hierro Mid can get pretty toasty at 60°F (15°C) and above.

Not a tiny streak of smoke passed through the boot's seams or pores in our breathability test. It is a 100% sealed upper that works best in the cooler season - spring, fall, and mild winter (not warm enough for harsh conditions).

Thus, we didn't hesitate to give this New Balance boot the lowest breathability score - 1 out of 5.

The boot's waterproofing works like a charm - be it in puddles, wet grass and underbrush, rain, or snow. We have zero complaints about the GTX itself.

But please keep in mind that the Hierro's flood level is not as high as the boot itself. Because its tongue is only semi-gusseted, there is a high risk of overflow if the water goes above the ankle level (around the fabric "Gore-Tex" branding on the side of the boot).

The brand's Toe Protect feature covers the Hierro Mid's toebox perimeter in the shape of a sturdy leather overlay. In addition to protecting the upper textile from scuffs and scratches, it also serves as a toe bumper to dampen the impact with rocks and roots.

But it's not just the leather that's wear-resistant in this boot. Based on our Dremel test, even the textile fabric on top of its toebox is ready for some action.

After 12 seconds of appying sandpaper to the top of the toebox, it showed merely cosmetic damage and earned a high toebox durability score of 4 out of 5.

The collar fabric, on the other hand, showed less resistance to abrasion and developed a hole in less than 4 seconds of sandpaper drilling. And when the inner lining loses its integrity, it affects the boot's waterproofing capacity too!

That's why we rated the Hierro Mid's heel padding durablity as low as 2 out of 5.

New Balance employs Vibram rubber to make the Hierro Mid's outsole. With an average reading of 85.5 HC, it showed decent hardness on our Shore C durometer test which is a good sign of longevity.

The boot's rubber blend also showed strong performance in our most abrasive Dremel test - 18 seconds of sandpaper drill at 10K RPM speed.

Having put up a fight, the Vibram rubber didn't let the Dremel burn more than 0.6 mm of its lug. This result is even better than average of hiking boots!

Our caliper measured 2.0 mm of outsole thickness (excluding the lugs) which is a little thinner than average. But considering the longevity of rubber, it shouldn't be a problem.

With a lug depth of 4.1 mm, the NB Fresh Foam X Hierro Mid GTX is just as toothy as the average hiking boot.

We found its Vibram Megagrip outsole to be effective on various types of surfaces but it is most as home on moderate terrain. We felt confident climbing up and over downed trees, stomping through puddles and light dirt, and even stepping on wet rocks.

What's more, each lug of this Vibram Megagrip iteration is studded with several micro dots which help the boot latch onto the ground harder during steep ascents and descents. The tackiness of these baby teeth was especially apparent during boulder-hopping.

On the downside, this Hierro boot has its limitations when it comes to braking on steep descents and conquering rock-heavy trails with some scrambling.

In our opinion, the New Balance Fresh Foam X Hierro Mid GTX is reasonably priced for what it has to offer. As a comfort- and cushioning-oriented day hiking boot for moderate terrain, its MSRP is somewhere in the middle of its closest competition - the Merrell Moab 3 Mid GTX and the Hoka Anacapa 2 Mid GTX.

None of the boot's components are reflective.

The tongue and collar of this New Balance hiking boot are adequately padded. Our caliper recorded a standard 10.7 mm of tongue thickness.

The half-length gussets of the Hierro Mid don't go all the way up its tongue. On one hand, it lowers the boots waterproofing capacity by lowering its flood level but on the other hand, you it offers some ankle freedom if you choose to loosen up the lacing.

A large finger loop at the back helps with the on-the-off. Its sturdy nature suggests that it's here to stay and won't snap after one use.

If you wear custom orthotics, you can easily swap the boot's removable insert for one of those.