MT-Helmets Thunder 4 R SV Highway B5 Full-Face Helmet – Matt Grey / Orange

One line on this page decides more purchases than the rest of it together: a Pinlock DKS435 Max Vision insert is in the box. Almost nothing at this price includes one, and it is the single accessory that turns a helmet from usable into trustworthy between October and March.

Why a visor fogs, and why ventilation cannot fix it

Fogging is condensation. Warm, saturated breath meets a surface below its dew point and the water leaves the air. The inside of a visor on a cold morning is exactly that surface.

Airflow removes fog only while you are moving. Sitting at a red light in November there is no airflow at all — and that is precisely when a visor mists, when your speed is lowest and a car is about to turn across you. No vent system, however good, solves a problem that only appears when the vents have nothing to work with.

What a Pinlock actually does

A Pinlock is a second lens held a fraction of a millimetre off the visor by two eccentric pins and sealed all round by a silicone bead. The trapped air is an insulator, so the inner surface stays above dew point and your breath finds nothing cold to condense on.

Max Vision means the lens is cut to the full width of the eye port instead of leaving a visible frame inside your peripheral vision — a real difference on a shoulder check. Fit it before the season, not at the roadside: the pins need adjusting until the bead just compresses, and that is a kitchen-table job.

About the Highway B5 finish

Matt throughout. The crown and the upper flank are a light, slightly cool grey; from the vent line the shell steps down through a mid grey into black at the chin bar, in hard-edged panels rather than a fade. A single orange wedge sits at the side vent, and THUNDER 4 R HIGHWAY runs in small type along the lower edge.

One accent colour on a three-value grey is a restrained way to build a helmet, and it has a practical side: grey panels of different lightness break up the shell's mass, so a fairly full sport-touring shape reads narrower than it is — without a graphic that will look dated in two seasons.

Ventilation: what MT enlarged for the R

The Thunder 4 R is the reworked Thunder 4 SV, and the intakes are one of the specific things MT made bigger. The other is the spoiler that covers the rear exhaust.

The pair matters more than either alone. Air moves through a helmet because of a pressure difference, not because a hole exists: intakes create high pressure at the brow, the exhaust creates low pressure at the tail, and the flow follows. A helmet with generous intakes and a poor outlet just presses air against your forehead and does nothing for the crown — which is where a full-face actually gets hot.

The nose deflector

A nasal deflector sits at the top of the chin bar and pushes your exhaled breath downwards instead of letting it run up the inside of the screen.

In mild weather it does most of the anti-fog work on its own, and it costs almost nothing. It is also the first part people take out because it touches the nose — and then wonder why the helmet started misting.

ECE 22.06 · no DOT published

The current European standard, mandatory since January 2024. Against the 22.05 it replaced: 18 impact points instead of five, several impact speeds, an oblique impact against an abrasive anvil measuring rotational loading, and a Brain Injury Criterion limit.

MT publishes no DOT marking for the Thunder 4 R. Several of their jets carry one; on the evidence available to us this model does not, and we state that rather than let the omission pass.

What the R changed

The 4 R is not a new helmet; it is the Thunder 4 SV reworked, and the SV had been MT's global best seller for two years before it. Four things were altered: larger air intakes, a reshaped spoiler, a revised screen-opening mechanism, and the Pinlock made standard equipment.

Only the last of those changes what you pay. The others are the kind of refinement that comes from a model selling in enough volume for the manufacturer to hear about its weak points — and the weak point most often named on the 4 SV was ventilation, which is exactly what MT went after.

Where it sits against the Braker SV

Below this helmet in our MT range sits the Braker SV, the entry to the same sport-touring class, and the two are worth putting side by side.

The Braker gives you the same HIRP construction, the same tool-free screen mechanism and the same drop-down shade for meaningfully less. What the Thunder adds is the Pinlock in the box, sizes up to 3XL, and the visor lock. If you ride through winter, the supplied anti-fog insert alone closes most of the price gap; if you ride in summer and daylight, the Braker is the same helmet class for less money.

Sizes and the rest of the equipment

Sizes run XS to 3XL, 53 to 66 cm. The MT-V-28C screen sits on the MT-M-28X mechanism with tool-free MT-QVSS release and a locking catch; a drop-down shade is built into the shell; the strap closes on a micrometric ratchet; the lining lifts out entirely and has recesses for MT-B01 Rider Sync speakers.

Washing the lining without ruining it

Not in a machine and never in a tumble dryer. The foam inside a cheek pad is closed-cell and does not survive a spin cycle; it comes back flatter, and a flattened pad is a helmet that has quietly become a size too large.

Hand-wash in lukewarm water with a little mild detergent, squeeze rather than wring, and dry away from radiators. Heat is what hardens helmet foam permanently.

What it does not have

• No DOT marking published.
• No independent safety rating. SHARP lists an older MT Thunder and Thunder 3 at four stars; those are different, earlier helmets and we do not carry their result across.
• No tinted screen in the box.

In the box

• MT Thunder 4 R SV helmet — Highway B5, matt grey and orange
• Protective bag, user manual and MT Helmets stickers
• Pinlock DKS435 Max Vision insert supplied as standard.

Size guide

Specification

• Model — MT-Helmets Thunder 4 R SV · Part number — 1375E15B52 (XS–3XL: …03 to …09)
• Colour / finish — Highway B5 — matt grey with orange
• Homologation — ECE 22.06 · no DOT published
• Safety rating — none for the 4 R; SHARP's Thunder entries are earlier models
• Type — full-face, sport-touring
• Shell — HIRP (High Impact Resistant Polymer), approx. 1,500 g
• Sizes — XS to 3XL (53–66 cm)
• Visor — MT-V-28C on the MT-M-28X mechanism, MT-QVSS quick release, visor lock
• Anti-fog — Pinlock DKS435 Max Vision included
• Sun visor — integrated drop-down shade
• Ventilation — enlarged intakes, reworked spoiler with rear exhaust
• Deflector — nose deflector fitted
• Retention — micrometric ratchet
• Interior — fully removable and washable, speaker pockets
• Communication — MT-B01 Rider Sync prepared; no system supplied
• Manufacturer — MT Helmets, Spain
• Care — hand-wash the lining in lukewarm water; never machine wash or tumble dry
• Replacement — after any impact, and after around five years regardless