OMM Core Tights Review

Overview

The Core Tights are an ultralight valley-to-summit PrimaLoft® Active leg piece for long winter runs, camping, and cold days in the hills.

Part of OMM’s Core Range — made entirely from PrimaLoft® ACTIVE ultra-light insulating fabric — the tights are built from a synthetic plume woven through a knitted mesh, aiming to offer the warmth of a fleece at less than half the weight.

They’re squarely aimed at trail runners, mountain marathoners, and fastpackers who need a serious insulation layer without the bulk or the sweaty overheating that traditional fleece tights tend to produce.

Key Specs

Spec	Detail
Weight	130g
Fabric	PrimaLoft® ACTIVE 75g/m²
Recycled Content	58% post-consumer recycled
Knee Panels	Stretch nylon (Flexile)
Waistband	Wide elasticated
Seams	Flatlock
Reflective Details	Yes
Certifications	bluesign®, Oeko-Tex
Fit	Slim/Fitted
Comparison	See how Core Tights compares to similar gear

Performance

The headline story with the Core Tights is the PrimaLoft® ACTIVE construction, and it’s genuinely different from a standard fleece tight. The fabric weaves PrimaLoft fibres onto a mesh, giving a super-high-volume and open structure that is exceptional at creating air pockets to insulate the wearer. The trade-off is baked right into the design: near-total air permeability means the lightest breeze can take away the trapped heat — but this also allows you to keep the Core layer on even when you’ve warmed up, thermoregulating by removing or unzipping your shell instead.

In practice, that means these tights are a two-piece system, full stop. The fabric does not provide any wind protection, so you will need a soft- or wind-shell over them if there is any cold wind. Once you accept that, the system genuinely works. Unlike conventional insulating trousers that can make you very sweaty, the Core Tights solve that problem — and when combined with overtrousers, they’re formidable in bad weather.

Wet performance is a real strength. Core works wet or dry with strong wicking properties to ensure you won’t stay wet for long, and the synthetic fill keeps insulating even when damp — a meaningful advantage over any down-based layer on a rain-soaked UK ridge.

The construction details are well thought-out for active use. Flatlock seams are positioned away from high-chafe areas to ensure comfort, while reflective logos provide visibility during low-light conditions. Panels of stretch nylon Flexile over the knees provide added protection with good wind and water resistance in that high-wear zone, and the wide elasticated waistband stays comfortable when layering.

One durability flag worth raising: PrimaLoft® ACTIVE’s open-mesh construction is inherently vulnerable to snagging. All weights of PrimaLoft Active are extremely vulnerable to snagging, so scrambling terrain, pack hipbelts, and bramble-covered trails all represent real risks to the fabric’s longevity. The Flexile knee panels address the highest-contact zone, but the rest of the tight is delicate by design.

They are very comfortable and cosy, and could easily be incorporated into a sleep system

— a genuine bonus for fastpackers looking to squeeze double-duty out of every gram. At 130g, that’s a compelling argument.

Pros & Cons

Pros

• Genuinely ultralight at 130g for a full-length insulated tight
• PrimaLoft® ACTIVE delivers fleece-level warmth at a fraction of the packed volume
• Continues to insulate when wet — reliable in UK-style mountain conditions
• Air permeability prevents overheating during high-output activity
• Flexile knee panels add targeted wind/water resistance where it matters most
• Flatlock seams reduce chafe risk during long efforts
• Doubles as a sleep layer, adding system versatility
• Strong sustainability credentials: 58% post-consumer recycled material, bluesign and Oeko-Tex approved
• Reflective detail useful for pre-dawn or post-dusk outings

Cons

• Useless without a wind layer — not a standalone option in any breeze
• The open-mesh PrimaLoft® ACTIVE fabric snags easily; longevity on rocky or technical terrain is a concern
• No pockets — not even a small key loop
• Narrow seasonal window: too warm for shoulder-season use, too vulnerable for aggressive winter scrambling without careful care
• OMM’s fitted cut may not suit everyone; sizing runs slim

Who Should Buy This

The Core Tights are built for endurance athletes, fastpackers, and trail runners who demand performance in all conditions.

More specifically, they shine for anyone doing high-output winter running or mountain marathons who needs real insulation without the bulk of a fleece tight — and who already carries a wind or waterproof shell layer as standard. They’d also appeal to the ultralight backpacker looking to shave grams from their sleep system. They’re not the right pick for a casual winter hiker who wants an all-in-one solution, or anyone doing technical scrambling where snag risk is high.

Verdict

The OMM Core Tights do something genuinely hard: they deliver meaningful insulation at 130g with enough breathability to keep a moving body from overheating. The mandatory shell pairing isn’t a flaw — it’s a system design that actually works — but you need to go in eyes open about that dependency and the fabric’s fragility. For winter trail runners and fastpackers already using a lightweight overtrouser, these are one of the most weight-efficient insulation options on the market for legs. Rating: 7.5/10.