BMW · Z4 · Bar

BMW Z4 bar chart (2.2-2.4 / 2.2-2.4)

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 Z4 2.2-2.4 bar converts to about 32-35 psi. Use the table, not a guess. Under-inflation cooks the shoulders of a Z4; over-inflation wears the centre rib and bangs every cat’s eye.

Bar, PSI and kPa

Bar-led conversions around the BMW Z4. 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

BMW Z4 placard versus sidewall

Sidewall PSI is a carcass maximum. Recommended operating pressure for this Z4 is the pillar sticker, near 34/34 psi.

Estimated pressure by tyre size (205/55R16 and others)

If your BMW Z4 no longer wears the OEM diameter, start at the row nearest 205/55R16 or 195/65R15 and confirm with the tyre maker’s load table.

Tyre size	Front PSI	Rear PSI	Front bar	Rear bar	Front kPa	Rear kPa	Note
205/55R16	34	34	2.34	2.34	234	234	Typical mid-compact OEM
195/65R15	34	34	2.34	2.34	234	234	Very common compact
225/40R18	36	36	2.48	2.48	248	248	Low-profile 18-inch
205/60R16	34	34	2.34	2.34	234	234	Taller 16-inch
245/40R18	36	36	2.48	2.48	248	248	Wide touring 18-inch
225/50R17	35	35	2.41	2.41	241	241	Touring 17-inch
215/55R16	34	35	2.34	2.41	234	241	Slightly wider 16-inch
225/45R17	35	35	2.41	2.41	241	241	Sport 17-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	36 psi / 2.48 bar

How to set the Z4

Measure before the school run, not after the M25.
Write LF / RF / RR / RL. Do not keep Z4 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 Z4.

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

BMW notes

BMW run-flats still want the placard. Comfort settings in the iDrive do not replace the door-pillar figure on this Z4.

Spare and inflator kit

A matching full-size spare on the BMW Z4 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 BMW sticker and this page disagree, the sticker wins.

Other BMW models

316 230 220 214 118 135 223 125

Questions about this Z4

Front versus rear on the BMW Z4?

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.

How often should I check a Z4?

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

Is the sidewall number correct on a BMW Z4?

No. Sidewall PSI is a maximum. The Z4 placard is the operating target, near 32-35/32-35 psi.

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.

What is that in bar and kPa for the Z4?

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

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