Dr. Wack "P21S" P21S "Reifen-Glanz" Tyre Care 400ml

The P21S "Reifen-Glanz" turns grey sidewalls black with no sling on the paint

What is the P21S "Reifen-Glanz"? A solvent-based spray dressing out of an aerosol can that pulls faded tyre sidewalls back to a satin black in a few minutes. Not meant for the tread, not for brake parts and not for anyone expecting material protection that holds for months.

P21S "Reifen-Glanz" is a sprayable tyre care product from Dr. Wack that leaves a thin, satin-gloss film on a dry tyre sidewall and tips faded grey back into black. The formula is solvent-based and does not mix with water, which is why the satin gloss is standing after a few minutes. A 400-millilitre can covers around 35 tyres. Most people search for it simply as P21S Reifenglanz.

The grey that disappears in the process is not road dirt. Tyre rubber carries antiozonants and protective waxes in the compound, and those migrate slowly from inside to the surface — the scene calls it blooming. Once up there they lay down as a film over the sidewall and catch ozone and UV before either can break the rubber chains apart.

When that protective film reacts with the oxygen in the air, it discolours to a dull grey-brown. For you that means what looks like a neglected tyre is the ageing protection doing its job and not a care mistake. The Reifen-Glanz does not take that layer off, it lays over the top and gives the sidewall back the colour the rubber had when it was new.

• Just under 11 ml per sidewall. By the manufacturer's figure a 400 ml can covers about 35 tyres, which is nearly nine sets of wheels out of one hand. Top it up after every second wash and it takes you through a whole season without swapping the can.
• The shine is standing before the buckets are put away. Because the formula is solvent-based and no water has to evaporate, the sidewall is dry to the touch rather than tacky after a few minutes. We give it 5 minutes before the car gets moved — that is enough even at ten degrees outside.
• A durability you can plan around instead of a promise. Dr. Wack states that the shine survives plenty of wet drives and around two to three trips through a car wash. That is not much against a dressing worked in with a pad, and it tells you in advance when to top it up.

Detailing1's tip from the shop: Fling marks on a freshly washed car, sling as the scene calls it, almost never come from the product, they come from the amount. Fog the sidewall until it glistens wet and you have laid down more than the rubber can take; the rest stands as a film of droplets and flies onto sills and arches in the first quick corner. We get a lot of messages about exactly those fine specks. Spray a single lap from 10 to 15 cm and then give the car 5 minutes.

The Reifen-Glanz belongs on a dry sidewall, never in the tread

The P21S Reifen-Glanz goes evenly onto clean, dry tyres from 10 to 15 centimetres away; any tread or wheel that catches some gets wiped off straight away with a soft cloth.

Dry is the harder condition of the two, not clean. On a damp sidewall the solvent-based film floats on the water instead of pulling into the top layer of rubber, and it dries off patchy. So after the wash, chamois the wheels first or give them 10 minutes to drip dry. And clean means degreased: if old tyre dressing or brake dust is still sitting on the sidewall, the new film bonds to that deposit instead of to the rubber. For that we run a tyre cleaner over the sidewall first.

The tread stays clear, and that is no formality. Dr. Wack explicitly rules out tyre treads along with brake discs and brake pads. A slick care film on the contact patch costs grip, and exactly where it counts: pulling away, braking, in a corner. If some does get into the tread while you spray, you wipe it off straight away and not after the drive.

On the amount, a simple sum helps. Just under 11 ml per sidewall is one lap, not a finger held down on the nozzle. Take the can twice round the tyre and you do not double the shine, only the amount that gets wiped off or flung off later. The film sits so thin that you can barely make it out in backlight — it only becomes visible once the sidewall is even.

The order at the wheel is always the same: the wheel first, then the tyre. Work the other way round and you rinse the fresh film straight back off with the cleaner. For that we take the wheel cleaner from the same line, let it run off, rinse and leave the wheel to dry. Only after that does the can come near it.

The shine lasts two car washes, the blooming it does not stop

The Reifen-Glanz is first of all a looks product. By the manufacturer's figure it survives plenty of wet drives and around two to three car washes, and it replaces no material protection for the rubber.

High gloss and material protection are two different goals, however much the shelves like to bundle them together. Shine comes from a thin film that throws light back in one direction instead of scattering it on the rough rubber surface. Material protection comes from the antiozonants being able to move up from inside the tyre. Dr. Wack additionally credits the film with keeping the tyres supple for longer — what it cannot do is resupply the ageing protection the rubber produces out of itself.

On durability, the honest placing: two to three car washes is the ceiling, not the norm. A heavy country downpour with spray off the front wheel visibly thins the film on the inner sidewall after a single drive, and spray dressings always last less time than dressings worked into the sidewall with a pad or a sponge. If you want black tyres after the wash, plan the can in as a fixed last step and not as a twice-a-year appointment.

The inner sidewall is the most thankless surface on the wheel. Nobody sees it, but it takes the full spray out of the arch and loses the film first. Spray only the outside and you have a two-tone wheel after the first wet drive. In winter the road salt comes on top, and at single-figure temperatures the solvent flashes off noticeably slower — then the sidewall wants 10 minutes of rest rather than 5.

Two things the spray cannot do. It does not stop the blooming — the grey-brown sidewall comes back as soon as the film has worn off, because the supply comes out of the rubber itself. And it is no replacement for checking your tyres: tread depth, age and pressure stay your job, and no dressing changes that. If you want an even look for wash day, the can is right. If you want weeks of durability, you need a dressing to work in.

The can is built for the day of the sale, not for the season

The P21S "Reifen-Glanz" earns its place with anyone who washes regularly themselves and wants the tyres done as the last job in under two minutes per wheel.

The can is strongest where looks count in a short window: a used car before the sales conversation, photos before the listing goes up, the car before the weekend. Dr. Wack names used cars as a use case itself, and that is about right. The messages we get about it mostly land in spring, when four- or five-year-old summer wheels come back out of storage and the sidewalls are grey instead of black after the winter.

The can fits less well for the wet-look fan. The result is satin gloss, not a wet high gloss; if you are after the greasy look, a gel is the better shout. And if you wash twice a year you get little out of it, because nothing of the film is left by the next time. For beginners, on the other hand, the aerosol can is the simplest route to black tyres: no applicator, no dosing, no gloves.

An aerosol can is always a compromise between active ingredient and propellant. At around 35 tyres out of 400 ml, that compromise sits well over on the active side: just under 11 ml per sidewall, spread over a single lap. It is dialled in where Dr. Wack has run the lab, production and filling under one roof since the 2024 new build, in Baar-Ebenhausen. How other cans, gels and foams solve the same job is over in tyre care.

The move no manufacturer prints on the can: do not spray onto the tyre, spray onto an old applicator or a folded piece of kitchen roll and take that once round the sidewall. You get through less product, nothing lands on the wheel, the caliper or the arch liner, and the film comes out more even than any freehand lap. That is where tyre care most often falls down — not on the product, on the way it goes on.

How to use the P21S "Reifen-Glanz"

One lap per sidewall, then five minutes of rest

The tyre goes under the can clean and dry. After the wash that means chamois the wheels or give them around 10 minutes to drip dry. On damp rubber the film floats and dries off patchy. If old tyre dressing or brake dust is still sitting on the sidewall, run a tyre cleaner over it first, or the new film bonds to the old deposit instead of to the rubber.

Shake the can hard, then spray evenly onto the sidewall from 10 to 15 cm away. One lap is enough. Reckon on just under 11 ml per tyre, which is around 35 tyres out of a 400 ml can. If you want to keep the overspray out of it altogether, spray onto an old applicator or a folded piece of kitchen roll and take that round the sidewall — cleaner and more even than freehand.

Everything that reached the tread, the wheel or the arch liner gets wiped off straight away with a soft cloth. Not later, but before it dries on. A slick care film has no business on the contact patch, and even less on the disc and the pads.

Then leave it standing 5 minutes before the car gets moved. In that time the solvent flashes off and the film goes dry to the touch. Drive off straight away and the excess flings off with the wheel rotation onto sills, arches and the rear end. With a fortnightly wash you top it up every second round, and the sidewall stays evenly dark.

Notes: If the tyre is standing in the sun and hand-warm, the solvent flashes off too fast and the film goes streaky; better to move the car into the shade then. By the manufacturer's figure the shine survives plenty of wet drives and around two to three car washes — plan it in as a recurring step, not as lasting protection. It does not stop the antiozonants blooming, and the grey-brown sidewall comes back as soon as the film is gone. No care product replaces tread depth, tyre age and pressure. Store the can cool and shaded and do not leave it lying in a hot boot in summer.