Tachyon 8" Black GTX

This boot was engineered to be our lightest most flexible boot ever for training and special operations. With GORE-TEX and a polishable toe, it weighs in at a mere 35oz.

$220.00

$66.00

70% OFF

Color: Black

Size: 10

Width: Men's D - Medium

Boot Size Guide & Fit Reference

Footwear Reference

Boot Size Guide

Use the charts below to convert your foot length into the correct US, UK, and EU size. All measurements are in centimeters.

Men's Footwear Sizing

US sizes run from 5 to 16, including half sizes.

US	UK	EU	Foot Length (cm)
5	4.5	37.5	23.1
5.5	5	38	23.5
6	5.5	39	24.1
6.5	6	39.5	24.5
7	6.5	40	25.0
7.5	7	41	25.5
8	7.5	41.5	26.0
8.5	8	42	26.5
9	8.5	43	27.0
9.5	9	43.5	27.5
10	9.5	44	28.0
10.5	10	44.5	28.5
11	10.5	45	29.0
11.5	11	46	29.5
12	11.5	47	30.0
12.5	12	47.5	30.5
13	12.5	48	31.0
13.5	13	48.5	31.5
14	13.5	49	32.0
14.5	14	49.5	32.5
15	14.5	50	33.0
15.5	15	50.5	33.5
16	15.5	51	34.0

Women's Footwear Sizing

US sizes run from 5 to 11.

US	UK	EU	Foot Length (cm)
5	2.5	36	22.0
5.5	3	37	22.5
6	3.5	37.5	22.8
6.5	4	38	23.1
7	4.5	39	23.5
7.5	5	39.5	23.8
8	5.5	40	24.1
8.5	6	41	24.5
9	6.5	41.5	25.0
9.5	7	42	25.5
10	7.5	43	26.0
10.5	8	43.5	26.5
11	8.5	44	27.0

Width Reference

Regular width is standard. Wide (EE) is offered in select styles only.

Men's US	Women's US	Regular (cm)	Wide EE (cm)
5	6	8.6	9.7
5.5	6.5	8.6	9.7
6	7	8.9	9.9
6.5	7.5	9.1	9.9
7	8	9.1	10.2
7.5	8.5	9.4	10.4
8	9	9.7	10.4
8.5	9.5	9.7	10.7
9	10	9.9	10.9
9.5	10.5	9.9	10.9
10	11	10.2	11.2
10.5	11.5	10.4	11.2
11	12	10.4	11.4
11.5	12.5	10.7	11.7
12	13	10.9	11.7
13	14	11.2	12.2
14	15	11.4	12.4
15	16	11.7	12.7

How to Measure Your Foot

A four-step process for an accurate reading at home.

Prepare a flat surface

Place a sheet of paper against a wall on a hard floor. Wear the socks you plan to use with the boots.

Stand with heel at the wall

Stand upright with your heel lightly touching the wall. Keep your weight evenly distributed on both feet.

Mark your longest toe

Mark the paper at the tip of your longest toe. Repeat for the other foot and use the larger value.

Measure and convert

Measure from the wall edge to the mark in centimeters, then match it to the size chart above.

Fit Tips & Half-Size Notes

Practical guidance to help you choose between sizes.

Order true to size

Most styles fit true to size when measured against the chart. If you are between sizes, size down for snug fits and up for thicker socks.

Half-size up for insulated boots

Insulated and winter-lined styles pack in extra material. Order a half size up to preserve circulation and comfort.

Try with your hiking socks

Measure with the socks you intend to wear. A thicker sock can shift you into a half size or wider width.

Wide feet need EE

If your foot spreads when standing, choose a wide (EE) variant when available instead of sizing up in length.

Break-in is normal

Leather boots soften and conform after several short wears. A snug first fit usually opens up by half a size.

Toe room rule

Leave roughly a thumb's width of space at the longest toe when standing. This prevents bruising on descents.

Quantity

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