Porsche · Boxster · Bar

Porsche Boxster tyre pressure in bar

Drivetrain: rear-wheel drive
Body: passenger car
PSI F / R: 32-35 / 32-35
Bar F / R: 2.2-2.4 / 2.2-2.4

bar

2.31 / 2.31

32-35 / 32-35 psi · 231 / 231 kPa

32-35 psi F · 32-35 psi R · 2.2-2.4 / 2.2-2.4 bar · 231/231 kPa

2.3 bar is not 23 psi. On this Boxster 2.2-2.4 bar converts to about 32-35 psi. Use the table, not a guess. Under-inflation cooks the shoulders of a Boxster; over-inflation wears the centre rib and bangs every cat’s eye.

Bar, PSI and kPa

Bar-led conversions around the Porsche Boxster. 2.2-2.4 bar is not “32-35 divided by ten”.

Bar	PSI	kPa
2.07	30	207
2.21	32	221
2.28	33	228
2.31	33.5	231
2.41	35	241
2.48	36	248
2.62	38	262
2.76	40	276
3.03	44	303
3.45	50	345
4.14	60	414

Porsche Boxster placard versus sidewall

Sidewall PSI is a carcass maximum. Recommended operating pressure for this Boxster is the pillar sticker, near 34/34 psi.

Estimated pressure by tyre size (225/45R17 and others)

Planning cold pressures for sizes often seen on a passenger car. This Boxster sample opens with 225/45R17, then 275/30R19 and 255/40R17.

Tyre size	Front PSI	Rear PSI	Front bar	Rear bar	Front kPa	Rear kPa	Note
225/45R17	34	35	2.34	2.41	234	241	Front sport size
275/30R19	36	37	2.48	2.55	248	255	Rear 19-inch
255/40R17	35	36	2.41	2.48	241	248	Rear stagger 17-inch
225/40R18	35	35	2.41	2.41	241	241	Front 18-inch
245/40R18	35	36	2.41	2.48	241	248	Square-ish sport
275/35R18	36	37	2.48	2.55	248	255	Wide rear
235/35R19	36	36	2.48	2.48	248	248	Front 19-inch
255/35R18	35	36	2.41	2.48	241	248	Rear stagger 18-inch

Load notes

Load moves the rear of a passenger car first. If the factory placard already has a “laden” column, use that instead of these sketches.

Condition	Front (est.)	Rear (est.)
Driver only	34 psi / 2.34 bar	34 psi / 2.34 bar
Full occupancy	34 psi / 2.34 bar	35 psi / 2.41 bar
Motorway + luggage	35 psi / 2.41 bar	38 psi / 2.62 bar

How to set the Boxster

Measure before the school run, not after the M25.
Write LF / RF / RR / RL. Do not keep Boxster numbers in your head.
Add air in short bursts toward 34 psi (2.31 bar) front and 34 psi rear.
If one corner is 4 psi down, hunt for a nail before you blame the weather.
Log date, ambient temperature and the four readings.

Temperature drift

Roughly 1 psi per 5–6 °C. The table uses 34 psi as a 20 °C baseline for this Boxster.

Ambient	Gauge (front mid)	Bar	kPa	Note
−5 °C (hard frost)	31 psi	2.14 bar	214 kPa	Gauge reads low; do not overfill once warm
0 °C	32 psi	2.21 bar	221 kPa	Gauge reads low; do not overfill once warm
8 °C (UK winter morning)	33 psi	2.28 bar	228 kPa	Gauge reads low; do not overfill once warm
20 °C (set cold here)	34 psi	2.34 bar	234 kPa	Baseline
30 °C	36 psi	2.48 bar	248 kPa	Do not bleed a hot tyre
38 °C (heatwave tarmac)	37 psi	2.55 bar	255 kPa	Do not bleed a hot tyre

Porsche notes

No special Porsche exception: the Boxster uses the door-pillar placard. Size estimates on this page only help if you have left the original load index behind.

Spare and inflator kit

A matching full-size spare on the Porsche Boxster usually follows the higher axle (often the rear, near 32-35 psi). A space-saver is commonly 60 psi / 4.1 bar — read that tyre’s own sidewall. An inflator kit is not a spare; check the sealant date.

If the Porsche sticker and this page disagree, the sticker wins.

Other Porsche models

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Questions about this Boxster

What PSI if I plus-size toward 255/40R17?

Keep load index at or above OEM. Low-profile sizes usually stay at or slightly above the placard. Use 225/45R17, 275/30R19 and 255/40R17 as a planning band.

What is that in bar and kPa for the Boxster?

Mid-points are about 2.31 bar (231 kPa) front and 2.31 bar (231 kPa) rear.

How often should I check a Boxster?

Monthly, before a long trip, and after a 10 °C weather swing. Include a full-size spare.

Front versus rear on the Porsche Boxster?

This row is 32-35 F / 32-35 R. Even when they match, a laden rear can justify a higher number if the sticker prints one.

Should I bleed pressure after a motorway run?

No. Heat raises the gauge. Set cold only. Bleeding a hot tyre leaves it low the next morning.

Handbook: placard · bar vs PSI · front vs rear · cold inflation