Vehicle technology guide

Tyre pressure: calculator, charts and what actually matters

The patch of road your car actually touches is about the size of four palms — and how big it is comes down to air pressure. Here you can work out which pressure suits your vehicle and your load, sanity-check the value on your door pillar, and find the charts for cars and trailers.

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Checked on 2 August 2026 · Swiss law (VTS and OBV) as of 1 July 2026

Person checking the tyre pressure on a car's front wheel with a digital gauge

At a glance

  • 2.0 – 3.0 bar Usual range for cars What counts is always the value on the door pillar or inside the fuel flap.
  • Cold How to measure The car has stood for two hours or driven at most 3 km slowly.
  • Monthly Check interval Tyres lose around 0.1 bar a month all by themselves.
  • +0.2 bar When loaded or driving briskly TCS recommendation, if your car has no separate full-load column.
  • 1 bar = 14.5 psi Units 1 bar is also 100 kPa. Switzerland works in bar.
  • 1.6 mm Minimum tread depth (law) Art. 58 para. 4 VTS. The federal roads office recommends 3 mm in summer, 4 mm in winter.

Tyre pressure calculator

What binds is the value on your car's door pillar. The calculator tells you whether it still suits your load and how much reserve sits behind it — and works out the pressure for trailers, where there is no placard at all.

You will find it in the vehicle registration document under «kerb weight».
The number after the size: 235/45 R18 98V.
Standard applies at 2.5 bar, XL and HL at 2.9 bar.
Determines how the kerb weight is distributed across the axles.
Enter it and the calculator checks it instead of guessing.
Leave empty if your sticker only names one value.
Calculated at 75 kg per person.
Roof box, ski or bike rack including its own weight.
The weight the drawbar presses onto the coupling.

Where the correct tyre pressure for your car is printed

There is exactly one binding source, and it is stuck to your car. Every table on the internet — including the ones further down this page — is orientation.

  • The driver's door pillar

    The most common spot. Open the driver's door fully and look for the sticker on the B-pillar or the door frame. The values are usually split by front and rear axle and by load condition.

  • Inside the fuel flap

    The second most common spot, particularly on French and Italian makes.

  • The glovebox

    Either as a sticker in the lid or as a table in the owner's manual.

  • The owner's manual

    Always contains the full table — including values for tyre sizes your car never came with from the factory.

Reading the sidewall: 235/45 R18 98V

What the markings on the sidewall mean
MarkingMeaning
235Tyre width in millimetres.
45Aspect ratio in per cent: the sidewall is 45 % of the width, so around 106 mm here.
RRadial construction. Careful: depending on the manufacturer, «RF» means either Reinforced or Run Flat — two completely different things.
18Rim diameter in inches.
98Load index. 98 means 750 kg per tyre — but only at 2.5 bar. That coupling is exactly what the calculator makes visible.
VSpeed index. V stands for 240 km/h.
Tyre sidewall marked 235/45 R18 98V – width, aspect ratio, rim diameter, load index and speed index
Tyre sidewall embossed MAX LOAD 650 kg and MAX INFLATION 3.0 bar – the tyre's own ceiling, not the vehicle's operating pressure
This is the marking in question: MAX INFLATION 3.0 bar is the tyre's own ceiling. Your vehicle's operating pressure is on the door pillar and almost always sits below it.

Do not confuse them: the «MAX PRESS» value on the sidewall is the maximum permitted cold inflation pressure of the tyre — not your vehicle's operating pressure. Inflate to that and you will almost always be running far too hard.

How to measure tyre pressure properly

Five minutes at a petrol station, once a month. One thing matters above all: the tyre has to be cold.

  1. Look up the target valueDoor pillar, fuel flap or glovebox. Note both figures — front and rear are often different, and many cars have a second column for a full load.
  2. Measure coldThe car should have stood for two hours, or driven at most 3 km slowly. Do not measure in direct sunshine. Pick the nearest petrol station, not the cheapest.
  3. Unscrew the valve capsAll four — and put them somewhere they cannot roll away. Do not forget the spare wheel: it loses air just the same and gets used precisely when nobody has checked it.
  4. Seat the connector squarelyPress it on firmly and at right angles until the hissing stops. At an angle, air escapes and the reading comes out too low.
  5. Bring it to the target valueAdd or release air until it is right. Then re-check each wheel — petrol-station gauges are not calibrated and disagree with each other.
  6. Caps back onThey keep dirt and moisture out of the valve. Finally, reset the monitoring system in the on-board computer, otherwise it keeps warning you — or, worse, stops warning you properly.
Compressed-air station at a petrol station for checking and correcting tyre pressure

Can only measure warm? Then do not set the target value — set target plus 0.3 bar, and do not release any air afterwards. Michelin gives exactly this rule of thumb. The higher pressure in a warm tyre is by design; take it away and you drive under-inflated once it cools.

Measuring cold — and what temperature really does

A tyre is a sealed, practically rigid volume. Its pressure therefore rises and falls with absolute temperature. Work that out in gauge pressure instead of absolute pressure and you understate the effect — which is exactly what the widespread rule of thumb «0.1 bar per 10 °C» does. It only holds for a tyre at just under 1.9 bar; at 2.5 bar it is 0.12 bar, and on a trailer tyre at 3.5 bar already 0.15 bar.

A tyre filled to 2.5 bar at 20 °C in the lowlands — what it reads at other temperatures
TemperatureReadingDifference
-15 °C 2.09 bar −0.41 bar
-10 °C 2.15 bar −0.35 bar
-5 °C 2.20 bar −0.30 bar
0 °C 2.26 bar −0.24 bar
+5 °C 2.32 bar −0.18 bar
+10 °C 2.38 bar −0.12 bar
+20 °C 2.50 bar +0.00 bar
+30 °C 2.62 bar +0.12 bar
+40 °C 2.74 bar +0.24 bar
+50 °C 2.85 bar +0.35 bar

Calculated with Amontons/Gay-Lussac on absolute pressure, ambient pressure for 400 m above sea level.

The practical point: a tyre you filled correctly at 20 °C in August reads only about 2.15 bar at −10 °C in January. That is 0.35 bar of under-inflation without any puncture. Topping up after the first cold snap is the most important tyre pressure action of the year.

A cold tyre reads a lower pressure than the same tyre when warm

Altitude: why the pressure rises in the mountains

Not one of the guides that rank on page one for tyre pressure in Switzerland mentions altitude. Yet sooner or later everyone here drives over a pass. So, in order.

A gauge never measures the absolute pressure inside the tyre — it always measures the difference to the surroundings. The tyre is sealed, so the amount of air inside does not change as you climb. What changes is the reference: the air up there is thinner, so the same gauge on the same tyre reads higher. That makes the tyre marginally harder, not softer — load capacity and deflection depend on the gauge pressure, and that goes up.

Ambient pressure and the reading of a tyre filled to 2.5 bar at 400 m
Altitude Example Ambient pressure Tyre reading
0 m Sea level 1.013 bar 2.45 bar
400 m Zürich, Bern, Luzern, Zug 0.966 bar 2.50 bar
800 m Einsiedeln 0.921 bar 2.55 bar
1'200 m Andermatt 0.877 bar 2.59 bar
1'600 m Davos 0.835 bar 2.63 bar
2'000 m Grimsel Pass 0.795 bar 2.67 bar
2'400 m Nufenen Pass 0.756 bar 2.71 bar

Calculated with the barometric formula of the ICAO standard atmosphere, at constant temperature.

From Zurich at 400 m up to the Nufenen Pass at 2400 m the reading gains about 0.21 bar. At the same time it is typically 10 to 13 °C colder up there, which takes 0.12 to 0.16 bar back off. The net result is around 0.05 bar — less than most petrol-station gauges can resolve. There is nothing to adjust for an alpine pass.

The effect that really counts is seasonal: from 20 °C in August to −10 °C in January, the same tyre loses 0.35 bar. That is seven times the pass effect — and that is where the work is.

Car on an alpine pass road – at altitude the indicated tyre pressure rises

Load, trailers and nose weight

Trailer tyres run at 3 to over 6 bar — in places double what a car tyre carries. It looks arbitrary, but there is a simple reason and a standard behind it.

A car almost always runs well below the load limit of its tyres. A loaded trailer is designed so that the axle load is practically equal to the load capacity of its tyres. And load capacity comes from air pressure. That is why a trailer nearly always ends up at the top of the table — not because «maximum pressure» is a rule.

The ETRTO trailer rule

On trailers with a top speed of up to 100 km/h, a car tyre may carry 10 per cent more than it does on a car — in exchange for 0.2 bar more pressure. For C tyres it is 5 per cent more capacity at 6 per cent more pressure. Concretely: a 155/80 R13 with load index 79 carries 437 kg on a car at 2.4 bar, and 480 kg on a trailer at 3.0 bar.

  • C tyres have no standard pressure

    The «C» after the size stands for Commercial and is standardised under ECE-R54. Unlike car tyres there is no single reference pressure — depending on size and load rating it sits between 3.75 and 5.75 bar. That is why the calculator asks for the value from your plate in C mode instead of inventing one.

  • The manufacturers contradict each other

    For the same nominal size, different trailer makers quote different values — for 225/55 R12C the documented spread runs from 5.3 to 6.2 bar, for 155 R13C from 2.8 to 3.5 bar. Usually the cause is a reinforced variant hiding behind the same designation. And the classic mix-up costs 1.5 bar: 185 R14 is a car tyre at 3.0 bar, 185 R14C a C tyre at 4.5 bar. So what counts is always your trailer's own plate, never a table off the internet — including this one.

  • Above 4.5 bar the valve becomes the issue

    Rubber snap-in valves of types TR413 and TR415 are only approved up to 4.5 bar cold. Trailers on 10- to 13-inch wheels, however, run at 6.25 bar. Those need metal valves — a point almost no tyre-pressure page mentions.

  • The petrol station often cannot do it

    Many station compressors barely get past 4 bar. For trailers with a high target pressure that means a garage, not a forecourt.

  • Nothing warns you on a trailer

    A tyre pressure monitoring system has only been mandatory for trailers since 1 April 2024, and only for the heavy O3 and O4 classes. An ordinary BE trailer has no warning light. It often stands for months, loses air while it does, and never says a word. Checking before every trip is therefore not advice on a trailer — it is what the manufacturers require.

  • On a trailer, age matters more than tread

    Tyres on trailers and caravans age faster than tyres that get driven — they stand, they sit in the sun, and they go brittle. The production date is the four-digit DOT number on the sidewall: «DOT 4518» means the 45th calendar week of 2018. The TCS recommends not using tyres over eight years old, even with tread left. Note: the frequently quoted six-year limit is a German rule from their 100 km/h approval scheme and does not apply in Switzerland.

  • FRT: not for the tow car

    If a tyre carries the marking «FRT» (Free Rolling Tyre) or «trailer use only», it may only go on axles that are neither steered nor driven. It is not a spare wheel for your car.

And the tow car?

The nose weight presses on the coupling — and that sits behind the rear axle. So it loads the rear axle by more than its own value while unloading the front, which noticeably changes steering and braking. In Switzerland the nose weight counts against the tow car's payload. The right move is therefore not a blanket surcharge but the «fully loaded» column from your car's own table — most cars have one. If yours does not, the TCS suggests about 0.2 bar more. The ADAC deliberately gives no blanket figure and points to the manufacturer table instead, where the gap between empty and fully loaded can reach 1 bar.

Speed limit for car-and-trailer combinations in Switzerland: 80 km/h as a rule (Art. 5 para. 1 lit. a no. 2 VRV), but since 1 January 2021 100 km/h on motorways and expressways if the trailer weighs at most 3.5 t and trailer, tow car and tyres are approved for it (Art. 5 para. 2 lit. c VRV). There is no plaque scheme as in Germany — the responsibility sits with the driver.

Estate car with a single-axle trailer – trailer tyres need a higher pressure than car tyres

Calculate trailer pressure

Tyre pressure charts

Every table lives in this page's source — including the collapsed ones. If you cannot or would rather not use the calculator, the values are still there.

Guide values by vehicle class
Guide values for cold inflation pressure by vehicle class
Vehicle class Examples 1–2 people Fully loaded
Small car VW Polo, Fiat 500, Toyota Aygo 2.0 – 2.3 bar 2.2 – 2.5 bar
Compact VW Golf, Ford Focus, Škoda Octavia 2.1 – 2.5 bar 2.3 – 2.8 bar
Mid-size / estate VW Passat, Audi A4 Avant 2.2 – 2.6 bar 2.5 – 3.0 bar
SUV / off-road Toyota RAV4, Škoda Karoq 2.3 – 2.8 bar 2.5 – 3.2 bar
Electric car VW ID.3, Tesla Model 3
Battery weight → often XL or HL tyres from the factory, with a higher target pressure.		 2.5 – 2.9 bar 2.7 – 3.2 bar
MPV / 7-seater VW Touran, Renault Espace 2.4 – 2.9 bar 2.7 – 3.3 bar
Van / transporter VW T6, Ford Transit, Fiat Ducato
C tyres. Rear axle noticeably higher than the front.		 2.8 – 3.5 bar 3.5 – 4.5 bar

This table is orientation, not a manufacturer figure. And that is meant more literally than it sounds: we compared the class tables in circulation and they contradict each other by up to 0.5 bar — for the rear axle of a small car one quotes 2.0–2.3 bar, another 1.8–2.0 bar, with no overlap at all. Neither cites a source. ADAC, Michelin and AMAG publish no class values for exactly this reason and point solely to the door pillar. Use the table to place the value you read there — not to replace it.

Load capacity: what a tyre carries at which pressure

This is the heart of the matter: the load index only applies at its reference pressure. As the pressure falls, so does the load capacity.

Load capacity in kg per tyre – standard tyres, reference pressure 2.5 bar
Load index 1.8 bar 2.0 bar 2.2 bar 2.4 bar 2.5 bar 2.6 bar 2.8 bar 3.0 bar
LI 84 (500 kg) 384 418 451 484 500 516 547 579
LI 88 (560 kg) 431 468 506 542 560 578 613 648
LI 91 (615 kg) 473 514 555 595 615 635 673 712
LI 94 (670 kg) 515 560 605 648 670 691 734 775
LI 97 (730 kg) 561 611 659 707 730 753 799 845
LI 99 (775 kg) 596 648 700 750 775 800 849 897
LI 101 (825 kg) 634 690 745 798 825 851 903 955
LI 104 (900 kg) 692 753 813 871 900 929 985 1041

Calculated from the load index table of UNECE Regulation No. 30 using the ETRTO relationship load capacity ∝ pressure0.80. The same arithmetic runs in the calculator above. The frequently quoted exponent 0.585 comes from the US standards and overstates European load capacity — we deliberately do not use it.

Load index table (LI 60 to 125)
Load index and the corresponding capacity per tyre
LIkgLIkgLIkg
60 250 82 475 104 900
61 257 83 487 105 925
62 265 84 500 106 950
63 272 85 515 107 975
64 280 86 530 108 1000
65 290 87 545 109 1030
66 300 88 560 110 1060
67 307 89 580 111 1090
68 315 90 600 112 1120
69 325 91 615 113 1150
70 335 92 630 114 1180
71 345 93 650 115 1215
72 355 94 670 116 1250
73 365 95 690 117 1285
74 375 96 710 118 1320
75 387 97 730 119 1360
76 400 98 750 120 1400
77 412 99 775 121 1450
78 425 100 800 122 1500
79 437 101 825 123 1550
80 450 102 850 124 1600
81 462 103 875 125 1650

Source: UNECE Regulation No. 30, Annex IV (LI 60–120); LI 121–125 from UNECE R54 via manufacturer documentation.

Trailers: pressure by size and by axle load
Cold inflation pressures quoted by trailer manufacturers (trailer service up to 100 km/h)
Tyre size LI kg / tyre Pressure Sources
135/80 R13 70 370 3.0 bar Matador (nur eine Quelle)
145/80 R13 75 425 3.0 bar Matador, Humbaur
155/70 R13 75 425 3.0 bar Matador, Humbaur
155/80 R13 79 480 3.0 bar Matador, Humbaur
155/80 R13 Reinf. 83 535 3.4 bar Matador, Böckmann
165/70 R13 79 480 3.0 bar Matador
165/70 R13C 88 585 3.75 bar Matador
185/70 R13 86 585 3.0 bar Matador, Humbaur, Böckmann
175 R14C 99 810 4.5 bar Matador
185 R14C 102 890 4.5 bar Matador, Humbaur, Böckmann, Unsinn
195 R14C 106 995 4.5 bar Matador, Humbaur
185 R15C 100 840 3.75 bar Matador
225/55 R12C – – 5.3 bar Böckmann, Unsinn
185/60 R12C – – 6.25 – 6.5 bar Unsinn, Böckmann, Anssems
195/55 R10C – – 6.25 bar Humbaur, Böckmann, Unsinn, Anssems
195/50 R13C 104 900 6.25 – 6.5 bar Humbaur, Böckmann, Anssems

Where the manufacturers disagree

Sizes for which different manufacturers quote different values
SizeDocumented spreadWhy
225/55 R12C 5.3 to 6.2 bar Largest documented spread for one and the same size designation – 0.9 bar.
155 R13C 2.8 to 3.5 bar Most likely reinforced variants hiding behind the same designation.
155/80 R13 2.8 to 3.4 bar The higher figure belongs to the reinforced variant (load index 83 instead of 79).
195/50 R13C 6.2 to 6.5 bar A small spread, but still relevant at this pressure level.

By axle load instead of by size

One manufacturer's mapping, quoting pressure by axle load
Axle loadCommon tyre sizesPressure
750 kg 145 R13 · 145/80 R13 · 155 R13 · 155/80 R13 2.8 bar
1000 kg 155/80 R13 2.9 bar
1200 – 1300 kg 185/70 R13 3.4 bar
1350 kg 195/70 R14 3.4 bar
1400 kg 185 R14 4.5 bar
1500 – 1750 kg 195/55 R10 · 195/50 R13 · 185/60 R12 6.25 – 6.5 bar

Your trailer's own plate is what counts. These figures come from manufacturer documentation and agree for the sizes listed — but they do not replace the specification for your particular vehicle.

Converting bar, psi and kPa
1 bar = 100 kPa = 14.5038 psi
barpsikPa
1.8 26.1 180
2.0 29.0 200
2.2 31.9 220
2.4 34.8 240
2.5 36.3 250
2.6 37.7 260
2.8 40.6 280
3.0 43.5 300
3.2 46.4 320
3.5 50.8 350
4.0 58.0 400
4.5 65.3 450
5.0 72.5 500
6.0 87.0 600
6.5 94.3 650

Switzerland and Europe work in bar, the sidewall usually states psi, and Japanese and Korean vehicles quote kPa. Mistake 35 psi for 3.5 bar and you inflate to almost double.

Speed index
Speed symbol and permitted top speed
Symbolkm/h
L120
M130
N140
P150
Q160
R170
S180
T190
U200
H210
V240
W270
Y300

Source: UNECE Regulation No. 30 §2.29.1. Commercial-vehicle tyres use the same km/h mapping; that series additionally starts at K (110 km/h) and ends at H. The index says up to which speed the load capacity applies — it does not override any speed limit.

Winter, summer and all-season tyres

Winter tyres need more pressure — you read that everywhere. The manufacturers, however, disagree, and the real point is a different one.

  • The argument about the winter surcharge

    Continental recommends 0.2 bar more for winter tyres in one place and states elsewhere that no winter surcharge is needed. Tyre retailers generally recommend it, vehicle manufacturers rarely mention it. In other words: set it and you do nothing wrong; leave it out and you do not either.

  • The real winter issue is temperature

    A tyre correctly filled to 2.5 bar at 20 °C in August reads only about 2.15 bar at −10 °C in January. Those 0.35 bar are not a measuring error but a real loss in effect — and considerably more than the surcharge people argue about. Topping up after the first cold snap is the single most important winter action.

  • Do it at the wheel change

    Wheels that sat in a cellar for six months have lost air. The target pressure is the same as in summer — it belongs to the car, not to the season. Important: after the change, re-teach the monitoring system, otherwise it either warns constantly or stops warning at all.

  • All-season tyres

    Exactly the same manufacturer figure applies as for summer and winter tyres. There is no separate all-season pressure.

  • Winter tyres and the speed index

    Winter tyres are the only ones allowed to carry a lower speed index than the car can reach — but then they must bear the snowflake symbol and be rated for at least 160 km/h, and the retailer has to give you a sticker for your field of view (Art. 59 paras. 3 and 4 VTS).

The warning light and the tyre pressure monitoring system

The yellow horseshoe with an exclamation mark is the most-searched tyre pressure question of all — and the worst explained.

Tyre pressure warning light: yellow tyre cross-section with an exclamation mark

  • What the light means

    At least one tyre is significantly under-inflated. Pull over at the next safe opportunity and check all four wheels, even if nothing looks wrong: you cannot see 0.5 bar of under-inflation on a modern tyre.

  • When it blinks first and then stays on

    Then the system is reporting a fault, not a pressure loss — typically a flat sensor battery, a sensor that was not re-taught after a wheel change, or a defective sensor. The pressure may be perfectly fine. Check it anyway, then go to a garage.

  • Direct or indirect

    Direct systems have a pressure sensor in every wheel and show real bar values. Indirect systems infer it from the ABS wheel speeds: a tyre with less air has a smaller rolling circumference and turns faster. Indirect systems are cheaper but need a reset after every correction — and they do not notice when all four tyres are equally low.

  • Do not forget the reset

    After every pressure correction and every wheel change the system has to be re-initialised — depending on the car via a button in the glovebox, a menu in the on-board computer, or at a garage. Skip it and you either get a permanent warning or, worse, a warning calibrated to the wrong reference.

  • A monitoring system does not replace checking

    A European field measurement on over a thousand vehicles still found 8 per cent of cars with a monitoring system running dangerous under-inflation of 0.5 bar or more. These systems warn late and barely cover the slow, even loss.

  • Mandatory in Switzerland

    For newly registered cars the requirement comes via Art. 103 para. 5 VTS, which refers to EU law — mandatory there for all new M1 registrations since 1 November 2014. Older cars need no system, and direct imports without EU whole-vehicle approval are exempt until the start of 2027. So «my car has no tyre pressure warning» is not automatically a defect.

Too little or too much pressure: what actually happens

The figures on this topic get copied from one site to the next. Here they come with a source — and with the spread, where the sources disagree.

Documented consequences of incorrect tyre pressure
EffectOrder of magnitudeContext
Extra fuel 0.3 l/100 km or up to 6 per cent at «too low» tyre pressure (TCS — the figure is not tied to any bar value). The percentage claims vary a lot: the German environment agency says 5 per cent per 0.5 bar, Continental about 2.5 per cent, the US Department of Energy only 1.5 per cent. At 15,000 km and 7 l/100 km that comes to roughly CHF 30 to 105 a year.
Wet braking distance up to +11 m at 1 bar off the target value (Michelin). The source does not state the initial speed.
Dry braking distance gets shorter Surprising, but measured: across several hundred braking runs DEKRA found the dry braking distance actually decreases as pressure drops. The catch is that steering precision and evasive behaviour deteriorate markedly, and the tyre overheats and wears. So under-inflation is no good idea on a dry road either — just not for the reason most guides give.
Aquaplaning up to 2× the risk if all four tyres are 0.5 bar low (TCS). The contact patch becomes flatter and wider, and the water is displaced less effectively.
Tyre life −20 % at 20 per cent under-inflation — 40,000 km become 32,000 km (Michelin).
How common it is 28 – 41 % of cars run at least 0.3 bar low — 41 per cent without a monitoring system, 28 per cent with a direct one (field measurement on 1,037 vehicles in Italy and Portugal, 2018). There is no Swiss survey on this.

The wear pattern gives the pressure away

Three tyre treads compared: shoulder wear from under-inflation, even wear at the correct pressure, centre wear from over-inflation
Wear pattern and cause
ConditionWhat you see on the tyre
Too little pressureBoth outer shoulders wear down while the centre stays. The tyre buckles inwards under the load.
Correct pressureEven wear across the whole width of the tread.
Too much pressureOnly the centre wears. The tread bulges outwards and the contact patch shrinks to a narrow strip.

A word on proportion: you occasionally read that a substantial share of all accidents traces back to low tyre pressure. That cannot be substantiated. Drawing on the federal accident statistics, the Swiss council for accident prevention records technical defects as a cause in fewer than 1 per cent of accidents involving serious injury — and notes that low tyre pressure is «rarely documented as a cause» among them. Tyre pressure is a comfort, cost and wear issue with a safety component, not a mass killer. That does not make it unimportant, just more honest.

Swiss law and fines

First surprise: there is no legally prescribed tyre pressure in Switzerland. The ordinance on the technical requirements for road vehicles does not name a single inflation figure for tyres.

  • What applies instead

    Art. 58 para. 1 VTS merely requires «pneumatic tyres of sufficient load capacity» — and a tyre only has sufficient capacity at the correct pressure. On top of that sits the general clause of Art. 29 SVG: vehicles may only be operated in a roadworthy condition. Art. 57 para. 1 VRV turns that into a duty on the driver to satisfy themselves of it. So the actual number always comes from the manufacturer.

  • Tread depth: 1.6 mm

    That is the one hard number (Art. 58 para. 4 VTS), and it applies «across the entire tread» — the worst point counts, not the average. Summer and winter tyres are treated alike. The federal roads office, however, recommends considerably more: at least 3 mm in summer and 4 mm in winter.

  • No winter tyre requirement

    The word «winter tyre» does not appear once in the traffic regulations ordinance. But anyone who causes an accident or obstructs traffic on unsuitable tyres lands via Art. 29 SVG at Art. 93 SVG — where the range runs from a fine to three years' imprisonment.

  • Fines

    A defective tyre costs CHF 100 as a fixed penalty, and the same again for a trailer (OBV annex 1 nos. 402.1 and 402.2). The keeper can be fined the same amount for putting the vehicle on the road — though not twice over if keeper and driver are the same person. Studded tyres outside the permitted window from 1 November to 30 April cost CHF 60, and studs on the motorway another 60. A fixed penalty is capped at CHF 300; beyond that it becomes a criminal report.

  • Overloading is directly connected

    Overload and you do not just need more air, you risk a fine of your own: from CHF 100 for up to 100 kg of excess weight, CHF 200 for combinations up to 3.5 t carrying more than 100 kg too much (OBV no. 300.1). What is assessed is the combined weight — car plus trailer.

Not legal advice. The original texts on fedlex.admin.ch are what govern. You will find specific fine amounts in the fines calculator.

Why this comes up in driver training

The vehicle and safety check is part of the practical driving test. Examiners ask you to point out control items on the car — lights, indicators, wipers, fluid levels and, yes, the condition of the tyres. If you can answer «where is the prescribed tyre pressure for this vehicle?» by opening the driver's door, you have made a good start. And anyone taking the test in their own car has to present it in a roadworthy state anyway — a tyre under 1.6 mm of tread is a reason to be turned away, not a blemish.

Frequently asked questions about tyre pressure

How many bar of tyre pressure does my car need?

On the great majority of cars the figure sits between 2.0 and 3.0 bar. What actually binds, though, is your manufacturer's specification — on the driver's door pillar, in the fuel flap or in the glovebox. Small cars are typically 2.0 to 2.3 bar, the compact class 2.1 to 2.5 bar, SUVs 2.3 to 2.8 bar and vans 3.0 to 4.5 bar. Those class figures are orientation, not a manufacturer statement for your car.

Is 2.5 bar of tyre pressure good?

2.5 bar is a perfectly plausible value for a mid-size car or a compact SUV — it would be on the high side for a small city car and clearly too low for a van. «Good» is whatever your manufacturer specifies for your tyre size and load condition. Incidentally, 2.5 bar is also the reference pressure at which the load index of a standard car tyre applies.

Is 3 bar too much tyre pressure?

Not as such. Plenty of MPVs, vans and fully loaded estates run 3 bar and more as standard. It is too much when it sits well above the manufacturer figure: the tread then bulges, the contact patch shrinks, the tyre wears in the middle and comfort suffers. The maximum cold inflation pressure is 3.2 bar for normal car tyres up to speed symbol T, and 3.5 bar for H, V, W, Y as well as XL, Reinforced and HL tyres.

Is 17 too high a tyre pressure?

The other way round: 17 is far too little — but the question mixes up the units. 17 psi is only 1.17 bar. That is dangerous under-inflation. A normal car value of 2.4 bar corresponds to about 35 psi. Rule of thumb: 1 bar is 14.5 psi, and 1 bar is 100 kPa.

Is 2 bar of tyre pressure too little?

For most vehicles yes, at least marginally. 2.0 bar is at the very bottom of what occurs at all and applies at best to light small cars with one person aboard. As soon as you are loaded or driving something bigger, 2.0 bar is not enough. From 0.5 bar below target the literature speaks of dangerous under-inflation.

How do I calculate the correct tyre pressure?

Physically, a tyre's load capacity depends on its inflation pressure: a tyre with load index 91 carries 615 kg — but only at 2.5 bar. From the wheel load you can therefore work backwards to the minimum pressure. That is exactly what the calculator on this page does: it distributes your weight across the front and rear axle, works out the load per tyre and from that the pressure required. The result is a minimum — your manufacturer's figure deliberately sits above it and must never be undercut.

Does tyre pressure have to be measured cold?

Yes. Every manufacturer figure applies to a cold tyre. «Cold» means, per Michelin: the car has stood for two hours or driven at most 3 km slowly. After half an hour on the motorway the pressure sits 0.3 to 0.5 bar higher — release air down to the target then and you drive markedly under-inflated once it cools. If you must measure warm, inflate to target plus 0.3 bar.

How much does temperature change tyre pressure?

A tyre is a sealed volume, so its pressure rises and falls with absolute temperature. On a tyre at 2.5 bar, 10 °C of difference means about 0.12 bar. From 20 °C in summer to −10 °C in winter that is 0.36 bar — a tyre correctly filled in August is genuinely under-inflated in January. The common rule of thumb «0.1 bar per 10 °C» only holds for a tyre at just under 1.9 bar and understates the effect at every usual pressure.

Do I have to adjust tyre pressure in the mountains?

No. The effect is real but small, and largely cancels itself out. A gauge measures the pressure difference to the surroundings. Drive from Zurich at 400 m up to 2000 m and the ambient pressure falls by about 0.17 bar — so the indicated tyre pressure rises by the same amount. At the same time it is around 10 °C colder up there, which takes roughly 0.12 bar back off. The net result is about 0.05 bar, less than most gauges can read. One thing worth knowing: the tyre gets marginally harder at altitude, not softer.

How many bar does a 750 kg trailer need?

That does not depend on the total weight but on the tyre. Typical 750 kg trailers run 145 R13 or 155/80 R13 and are specified by their makers at around 2.8 to 3.0 bar. Trailers on small wheels such as 195/50 R13C or 195/55 R10C, by contrast, need 6.25 to 6.5 bar. What binds is your trailer's plate: different manufacturers quote figures for the same tyre size that differ by up to 0.9 bar.

Why do trailer tyres need so much more pressure than car tyres?

Because they almost always work at their load limit, and load capacity comes from air pressure. On top of that sits an ETRTO rule: on trailers with a top speed of up to 100 km/h a car tyre may carry 10 per cent more than on a car — in exchange for 0.2 bar more pressure. For C tyres it is 5 per cent more capacity at 6 per cent more pressure. A 155/80 R13 carries 437 kg on a car at 2.4 bar and 480 kg on a trailer at 3.0 bar.

Do I have to raise the tow car's tyre pressure when towing?

Yes — but do not apply some arbitrary surcharge; take the «fully loaded» column from your car's own table. The nose weight presses on the coupling behind the rear axle, counts against the tow car's payload in Switzerland, and loads the rear axle while unloading the front. If your car has no full-load column, the TCS suggests around 0.2 bar more.

What does the yellow tyre pressure warning light mean?

The horseshoe symbol with an exclamation mark indicates that at least one tyre is significantly low. Pull over at the next safe opportunity and check all four wheels, even if nothing looks wrong: you cannot see 0.5 bar of under-inflation. If the light blinks first and then stays on, that is a system fault rather than necessarily a pressure loss. After correcting the pressure or changing wheels, the system has to be reset or re-taught.

Is a tyre pressure monitoring system mandatory in Switzerland?

For newly registered cars, yes: Art. 103 para. 5 VTS refers to EU law, which has required a tyre pressure monitoring system for all new M1 registrations since 1 November 2014. Older vehicles need none. For trailers the requirement has only applied since 1 April 2024 and only to the heavy O3 and O4 classes — so an ordinary BE trailer has no warning light. Which is exactly why you have to check it yourself.

How much fuel does low tyre pressure cost?

The TCS puts the extra consumption at up to 0.3 l/100 km, or up to 6 per cent. At 15,000 km a year and 7 l/100 km that is roughly 45 litres or about 90 francs. The sources vary considerably, though: the German environment agency cites 5 per cent per 0.5 bar, the US Department of Energy only about 1.5 per cent. An honest answer is therefore a range of roughly CHF 30 to 105 a year.

Does low tyre pressure lengthen the braking distance?

On a wet road yes — Michelin cites up to 11 metres of difference at 1 bar off target, though without stating the initial speed. On a dry road it is surprisingly the other way round: across several hundred braking runs DEKRA measured the dry braking distance getting shorter as pressure fell. The catch is that steering precision and evasive behaviour deteriorate, and the tyre overheats and wears. So under-inflation is still a bad idea on a dry road — just not for the reason most guides give.

How often should tyre pressure be checked?

Once a month, on cold tyres, plus before any longer trip. Tyres lose air by diffusion all on their own — the TCS cites around 0.1 bar a month, Michelin 0.07 bar, while the ADAC is considerably more conservative at 0.1 bar over three months. If a tyre loses noticeably more, that is not normal seepage but a job for a garage.

Is a nitrogen filling worth it?

Not for an ordinary car. Normal air is already 78 per cent nitrogen, and commercial tyre gas about 90 per cent. The ADAC measured that the pressure difference stays within a few hundredths of a bar even after months and advises against it; the TCS puts it similarly. The temperature effect is exactly the same with nitrogen, and it does not replace regular checking either.

Do winter tyres need more pressure?

The manufacturers disagree. Continental recommends 0.2 bar more, but states elsewhere that no winter surcharge is needed. What is not in dispute is the actual point: the cold season itself drops the pressure by up to 0.35 bar. Fill to the target value in winter, measuring cold, and you have done everything right — the surcharge is a matter of taste, the topping-up is not.

Is there a legally prescribed tyre pressure in Switzerland?

No. The ordinance on the technical requirements for road vehicles does not contain a single inflation value for tyres. Art. 58 para. 1 VTS merely requires «pneumatic tyres of sufficient load capacity» — and a tyre only has that at the correct pressure. Legally, tyre pressure is therefore covered by the general roadworthiness requirement of Art. 29 SVG. The only hard number concerns tread depth: 1.6 mm under Art. 58 para. 4 VTS, and a defective tyre carries a CHF 100 fixed penalty.

The vehicle check is on the test — and you can practise it

Tyre pressure, tread depth, warning lights: the practical test asks about them, and in your first lesson someone explains them on a real car. Find a driving school near you.

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Sources

  1. UNECE Regulation No. 30, Annex IV — load index table (LI 60–120).
  2. Swiss Ordinance on the Technical Requirements for Road Vehicles (VTS, SR 741.41), in particular Art. 58, 59, 61/62, 103 para. 5 and Art. 187.
  3. Swiss Fixed Penalty Ordinance (OBV, SR 314.11), annex 1 nos. 402 and 502, as of 1 July 2026.
  4. Swiss Traffic Regulations Ordinance (VRV, SR 741.11) and Road Traffic Act (SVG, SR 741.01), Art. 29 and 93.
  5. ETRTO Standards Manual, load/inflation tables; Continental tyre guide 2025, tables 1–4 and the trailer operating rules.
  6. TCS: tyre pressure monitoring systems test, tyre FAQ, CO₂ fact sheet.
  7. Michelin Switzerland: «Which tyre pressure for my car?» and «How to inflate tyres».
  8. ADAC: «The right tyre pressure»; DEKRA Road Safety on inflation pressure and braking distance.
  9. Swiss council for accident prevention (bfu) / sinus-plus.ch, based on federal accident statistics, on technical defects as an accident cause.
  10. Federal roads office (ASTRA) blog «Winter tyres: from October to Easter» on recommended tread depths.

Last checked on 2. August 2026.