Our verdict

The Addiction 15 excels as a niche shoe, masterfully prioritising stability and durability—qualities crucial for severe pronators. We found that Brooks maximised these features, albeit at the expense of weight and versatility, as we found that it's heavier compared to most competitors. Nevertheless, we believe it's an outstanding choice for runners who need firm support and don't mind its massive heft.

Pros

  • Plenty of stability
  • Incredible outsole durability
  • Effective GuideRails technology
  • Accommodates custom orthotics
  • Grippy on most surfaces
  • Ideal for bigger runners
  • Highly breathable
  • Fairly priced

Cons

  • Lacks flexibility
  • Quite heavy
  • Firm midsole

Audience verdict

79
Decent!

Who should buy

We're convinced the Addiction GTS 15 from Brooks excels in specific areas that make it a top pick for certain individuals. We think its:

  • Ideal for heavier runners seeking substantial support.
  • Perfect for those who prefer firmer cushioning and don’t mind added weight.
  • Excellent for runners concerned with pronation and outsole durability.

Brooks Addiction GTS 15

Who should NOT buy

Despite its strengths, we do not recommend the Addiction GTS 15 for certain runners. Those who prefer lighter footwear should steer clear of this model—instead, we suggest the Hoka Gaviota 5, which offers excellent support in a more manageable weight.

We also think that runners who find firmer foams uncomfortable might struggle with the Addiction GTS 15. While firmness does typically enhance support, if you're willing to sacrifice some stability, consider the ASICS Gel Kayano 30 or the Brooks Glycerin GTS 21 as better alternatives.

Brooks Addiction GTS 15 parts

Breathability

The Addiction GTS 15, which we purchased and tested in our lab, might not appear breathable at first glance due to its all-black colorway, right?

However, we discovered that it actually offers excellent ventilation. After conducting our eye-catching smoke test, we rated it 4 out of 5—a highly favourable score suitable for all seasons.

Our examination with a light revealed the secret behind its optimal ventilation. The engineered mesh upper features hundreds of tiny holes that effectively allow air and moisture to pass through.

Brooks Addiction GTS 15 microscope

Intrigued by the abundance of ventilation holes, we next examined them under our microscope.

Brooks Addiction GTS 15 mesh

We observed that the mesh cleverly opens slightly every few millimetres with remarkable precision.

Concluding this section, we analysed the sliced upper and found the material to be well padded, providing a perfect balance of comfort and breathability.

Test results
Addiction GTS 15 4
Average 3.8
Compared to 235 running shoes
Number of shoes
1
Breathability
5

Durability

Toebox durability

We already know that the Addiction boasts good ventilation, but does this compromise its durability? Surprisingly, no.

After our Dremel test, when the sandpaper tip ceased spinning, we discovered only minor damage. This translates to a 3/5 on our durability scale—a very positive result indeed!

Brooks Addiction GTS 15 Toebox durability
Test results
Addiction GTS 15 3
Average 2.4
Compared to 169 running shoes
Number of shoes
1
Toebox durability
5

Heel padding durability

The good news continues with the heel padding.

We found only minimal, very reasonable damage after our tests, so we've upgraded its rating to 4 out of 5!

Brooks Addiction GTS 15 Heel padding durability
Test results
Addiction GTS 15 4
Average 3.2
Compared to 165 running shoes
Number of shoes
1
Heel padding durability
5

Outsole hardness

As we flipped the shoe, our focus turned to the hardness of the Blown Rubber outsole.

Brooks Addiction GTS 15 blown rubber

The outsole coverage is impressive. We also discovered countless cutouts that enhance the shoe's longitudinal flexibility.

We pressed our Shore C durometer and recorded a measurement of 89.4 HC, indicating its robust nature. This shoe is just built like a tank.

Brooks Addiction GTS 15 Outsole hardness
Test results
Addiction GTS 15 89.4 HC
Average 80.5 HC
We use an average of four tests. The photo shows one of those tests.
Compared to 286 running shoes
Number of shoes
52.1 HC
Outsole hardness
93.0 HC

Outsole durability

The high hardness of the outsole suggested promising results for our final Dremel test.

True to our expectations, after the Dremel concluded its work, we observed a minor 0.6 mm indentation, indicating an excellent potential for longevity.

Brooks Addiction GTS 15 Outsole durability
Test results
Addiction GTS 15 0.6 mm
Average 0.9 mm
Compared to 147 running shoes
Number of shoes
0.0 mm
Outsole wear
2.0 mm

Outsole thickness

We had already proven the fantastic durability of the outsole, but when we measured its thickness with our vernier callipers, we were astounded. At 6.0 mm, it's one of the thickest outsoles we've ever tested in our lab, especially notable since it's made of hard rubber, not a super-soft blend like the ASICS Cumulus 26.

Brooks Addiction GTS 15 rubber

This suggests that the outsole will likely last a veeeery long time. However, we also discovered that such a thick, hard outsole can mute the ride, sometimes making it feel like a brick.

Brooks Addiction GTS 15 Outsole thickness
Test results
Addiction GTS 15 6.0 mm
Average 3.2 mm
Compared to 305 running shoes
Number of shoes
0.0 mm
Outsole thickness
6.6 mm

Weight

When we first handled the Addiction GTS 15 in our lab, we anticipated it would tip the scales at well over 10 oz. However, at 12.5 oz or 353g, it feels like too much.

These shoes are HEAVY, and we feel they are only suitable for those willing to sacrifice lightness for durability.

Brooks Addiction GTS 15 Weight
Test results
Addiction GTS 15 12.45 oz (353g)
Average 9.38 oz (266g)
Compared to 306 running shoes
Number of shoes
5.26 oz (149g)
Weight
12.56 oz (356g)

Cushioning

Heel stack

We recently observed that the Addiction GTS 15 is packed with more foam than before. Now, it's essential to assess in the lab Brooks' claims by measuring its stack.

Brooks Addiction GTS 15 foam

The shoe features a heel height of 36.5 mm, which offers substantial cushioning. However, it's important to note that not all of this height is due to foam—as we've previously demonstrated, much of it includes the hard rubber outsole... and the insole.

Brooks Addiction GTS 15 Heel stack
Test results
Addiction GTS 15 36.5 mm
Average 33.7 mm
Compared to 305 running shoes
Number of shoes
7.6 mm
Heel stack
45.7 mm

Forefoot stack

The forefoot cushioning is notably thinner than the heel, measuring just 24.4 mm. This design suggests us that the shoe is specifically tailored for heel strikers, offering a clear indication of its intended user base.

Brooks Addiction GTS 15 Forefoot stack
Test results
Addiction GTS 15 24.4 mm
Average 25.0 mm
Compared to 305 running shoes
Number of shoes
7.6 mm
Forefoot stack
36.9 mm

Drop

As you might guess from our previous tests, this shoe has a substantial drop. Brooks reports it as 12.0 mm, and our measurements show 12.1 mm. This minimal discrepancy is truly impressive, as we typically encounter variances of 3 or 4 mm.

With its high drop and reduced cushioning in the forefoot, it's clear that this motion control shoe is made for those who strike the ground with the rearfoot.

Brooks Addiction GTS 15 Drop
Test results
Addiction GTS 15 12.1 mm
Average 8.7 mm
Compared to 305 running shoes
Number of shoes
-0.8 mm
Drop
16.1 mm

Insole thickness

The insole, at 5.6 mm, is slightly more cushioned than what we typically find in running shoes. However, it's important to note that this shoe is far from being an average daily trainer.

Brooks Addiction GTS 15 Insole thickness
Test results
Addiction GTS 15 5.6 mm
Average 4.5 mm
Compared to 301 running shoes
Number of shoes
1.5 mm
Insole thickness
7.3 mm

Midsole softness

Note: a low durometer measurement equals a soft material, whereas a high measurement means it's firm.

Two words fully describe this shoe—heavy and firm. We've discussed its weight, and now it's time to evaluate its foam.

During our test runs, the BioMoGo DNA foam felt exceptionally firm, and with a measurement of 30.1 HA on our durometer, our findings confirm this. Yet, we're not taken aback by this result. A firm midsole is crucial for a motion control shoe as it provides essential support for those with severe pronation issues.

Brooks Addiction GTS 15 Midsole softness
Test results
Addiction GTS 15 30.1 HA
Average 21.4 HA
We use an average of four tests. The photo shows one of those tests.
Compared to 233 running shoes
Number of shoes
8.5 HA
Midsole softness (soft to firm)
41.5 HA

Difference in midsole softness in cold

To evaluate the Addiction GTS 15's performance in extremely cold conditions, we placed it in a freezer for 20 minutes before conducting another test with the durometer. Following the freeze, it showed a change of 14.9%, which is outstanding.

Brooks Addiction GTS 15 Difference in midsole softness in cold
Test results
Addiction GTS 15 14.9%
Average 25.5%
Compared to 232 running shoes
Number of shoes
0%
Difference in midsole softness in cold
100%

Stability

Lateral stability test

The Addiction GTS 15 may resemble a brick, but its stability is unmatched. We can't recall another shoe that offers such a robust sense of stability for heel strikers.

This remarkable stability is also partly due to Brooks' GuideRails technology.

Brooks Addiction GTS 15 GuideRails

Essentially, these are two hard plastic pieces embedded into the sides of the heel, guiding the feet forward and preventing collapse—and they certainly do their job!

Torsional rigidity

This shoe is geared specifically to those with severe pronation issues. Given this, it was no surprise that bending or twisting the Addiction GTS 15 proved incredibly challenging. Consequently, we awarded it a top score of 5/5 for its massive rigidity.

Naturally, a shoe built for substantial stability isn't expected to be flexible, yet this one is exceptionally rigid, akin a carbon-plated model.

Test results
Addiction GTS 15 5
Average 3.3
Compared to 284 running shoes
Number of shoes
1
Torsional rigidity
5

Heel counter stiffness

We anticipated a similar result in this test, yet we were surprised. Instead of a rigid, steel-like heel counter, Brooks opted for a more balanced approach akin to daily trainers, with a moderate stiffness rating of 3/5.

This design choice enhances comfort, particularly for those with sensitive heels, and seems wise given the shoe's sufficient stability.

Test results
Addiction GTS 15 3
Average 2.8
Compared to 268 running shoes
Number of shoes
1
Heel counter stiffness
5

Midsole width in the forefoot

We confirmed the presence of reflective elements, though we found them only in the toebox and their visibility is less than impressive.

Brooks Addiction GTS 15 Midsole width in the forefoot
Test results
Addiction GTS 15 113.5 mm
Average 113.8 mm
Compared to 306 running shoes
Number of shoes
100.5 mm
Midsole width in the forefoot
126.5 mm

Midsole width in the heel

Our initial observation was thoroughly confirmed when we measured a remarkably wide 99.9 mm at the heel—providing a massive, stable landing platform that distinctly stands out from average shoes.

This expansive design offers exceptional support for rearfoot strikers!

Brooks Addiction GTS 15 Midsole width in the heel
Test results
Addiction GTS 15 99.9 mm
Average 90.5 mm
Compared to 306 running shoes
Number of shoes
74.9 mm
Midsole width in the heel
106.6 mm

Flexibility

Stiffness

The Addiction GTS 15, obviously lacking a plate, had a moderate performance in our 90-degree bend test with a force of 30.1N. It's essential for the shoe to maintain some flexibility longitudinally, given its extreme rigidity in torsional tests—this flexibility is key for enhancing comfort.

Remember, while it's critical for a supportive shoe to control lateral forces, having a sole that can flex longitudinally poses no issues in that regard and enhances the overall comfort for daily runs and various activities.

Test results
Addiction GTS 15 30.1N
Average 29.1N
We use an average of four tests. The video shows one of those tests.
Compared to 288 running shoes
Number of shoes
2.2N
Stiffness
94.4N

Difference in stiffness in cold

We repeated the test after chilling the shoe for 20 minutes, mirroring our midsole softness assessment. 

The outcome showed only a 12.5% increase in stiffness, confirming that the shoe retains considerable flexibility.

Test results
Addiction GTS 15 12.5%
Average 35.9%
Compared to 288 running shoes
Number of shoes
0%
Difference in stiffness in cold
148%

Size and fit

Toebox width at the widest part

Our initial measurement in the toebox—always taken at the widest part—showed that the Addiction GTS 15 spans an accommodating 97.4 mm in our US 9 (D) pair, comfortably fitting most foot sizes.

Moreover, it's quite impressive that Brooks offers this model in a full range of widths: Narrow (B), Regular (D), Wide (2E), and Extra-Wide (4E). There are only a handful of models on the shelves offering such a variety of widths!

Brooks Addiction GTS 15 Toebox width at the widest part
Test results
Addiction GTS 15 97.4 mm
Average 98.4 mm
Compared to 306 running shoes
Number of shoes
89.5 mm
Toebox width at the widest part
109.1 mm

Toebox width at the big toe

We took a second measurement in the big toe area, and it registered slightly lower than expected at 75.8 mm. However, for those needing extra room in the toe cap—as we mentioned earlier—this shoe is available in 2E and 4E sizes.

Brooks Addiction GTS 15 Toebox width at the big toe
Test results
Addiction GTS 15 75.8 mm
Average 78.2 mm
Compared to 180 running shoes
Number of shoes
60.4 mm
Toebox width at the big toe
92.5 mm

Tongue: gusset type

We shifted our focus to the tongue area and noted that the tongue is not gusseted. However, for £140, we find this acceptable, though not ideal.

Brooks Addiction GTS 15 Tongue: gusset type
Test results
Addiction GTS 15 None

Comfort

Tongue padding

The tongue is exceptionally comfortable, featuring a single thick slab of foam measuring 7.5 mm.

Brooks Addiction GTS 15 tongue

We've found that it's enough to protect the instep, even when tightening the laces tightly, without being excessively padded.

Brooks Addiction GTS 15 Tongue padding
Test results
Addiction GTS 15 7.5 mm
Average 5.6 mm
Compared to 303 running shoes
Number of shoes
0.5 mm
Tongue padding
14.2 mm

Heel tab

In line with most Brooks shoes, we didn't find a heel tab on the Addiction GTS 15.

Brooks Addiction GTS 15 Heel tab
Test results
Addiction GTS 15 None

Removable insole

The insole, dubbed by Brooks as Ultimate Sockliner, features a contoured design that cradles the feet, much like a bathtub, enhancing stability. We've also observed that it's removable.

Brooks Addiction GTS 15 Removable insole
Test results
Addiction GTS 15 Yes

Misc

Reflective elements

We confirmed the presence of reflective elements, though we found them only in the toebox and their visibility is less than impressive.

Test results
Addiction GTS 15 Yes