UK · EU reference Tyre Pressure

235/55R18 · SUV / crossover · Bar

235/55R18 bar chart (2.41 bar planning figure)

Size
235/55R18
Class
SUV / crossover
Planning PSI
35
Planning bar
2.41

bar

2.41

35 psi · 241 kPa · not a second factory sticker

235/55R18 · 35 psi · 2.41 bar · 241 kPa — estimates. Placard wins.

European stickers print bar. 235/55R18 often sits near 2.41 bar on a SUV / crossover (35 psi / 241 kPa). 2.41 bar is not “35 divided by ten”. TPMS typically warns near 26 psi (about 25% below a 35 psi target). That is already a soft tyre.

Bar, PSI and kPa

Convert around the 235/55R18 band. 2.41 bar is about 35 psi — not 23, not 33 unless the maths says so.

BarPSIkPa
2.1431214
2.2132221
2.2833228
2.3434234
2.4135241
2.4836248
2.5537255
2.6238262
2.6939269
2.7640276
2.8341283
2.9042290
2.9643296
3.0344303
3.1045310
3.1746317
3.2447324

Estimated 235/55R18 pressure by load

Plus-sizing to 235/55R18 from a taller OEM tyre usually keeps the same placard if the load index is equal or higher.

ConditionFront (est.)Rear (est.)
Driver only / unladen35 psi / 2.41 bar / 241 kPa35 psi / 2.41 bar / 241 kPa
Typical occupancy35 psi / 2.41 bar / 241 kPa36 psi / 2.48 bar / 248 kPa
Motorway + luggage (sketch)36 psi / 2.48 bar / 248 kPa37 psi / 2.55 bar / 255 kPa

Placard versus sidewall

If a forum says “all 235/55R18 run 35 psi”, ignore it. A Qashqai and a Golf can share a size and not share a sticker.

What 235/55R18 means

Read 235/55R18 as width / aspect R rim. Nothing in the size string is a pressure. Pressure lives on the car, not moulded as 205 or 55.

Plus-size mid-SUV 18-inch. Rim diameter 18 in; section 235 mm. Estimates on this page assume a typical load index for the SUV / crossover class.

Cars often seen on 235/55R18

These catalogue models are often seen on 235/55R18 or a close OEM neighbour. Open the vehicle chart for axle-specific PSI and bar.

Hyundai TucsonKia SportageMazda CX-5

How to set 235/55R18

  1. Park so the 235/55R18 tyres are cold (three hours, or less than about a mile).
  2. Read the door-pillar placard for that car — not the 235/55R18 sidewall maximum.
  3. If the sticker is missing, 35 psi / 2.41 bar is only a SUV / crossover planning figure for this size.
  4. Set all four with a calibrated gauge. A 3 psi miss on one corner shows up as a wander.
  5. Refit valve caps and reset TPMS if the handbook asks for a relearn.

Temperature drift

Roughly 1 psi per 5–6 °C. The table uses 35 psi as a 20 °C baseline for 235/55R18.

AmbientGaugeBarkPaNote
−5 °C (hard frost)32 psi2.21 bar221 kPaGauge reads low; do not overfill once warm
0 °C33 psi2.28 bar228 kPaGauge reads low; do not overfill once warm
8 °C (UK winter morning)34 psi2.34 bar234 kPaGauge reads low; do not overfill once warm
20 °C (set cold here)35 psi2.41 bar241 kPaBaseline for this size sketch
30 °C37 psi2.55 bar255 kPaDo not bleed a hot 235/55R18
38 °C (heatwave tarmac)38 psi2.62 bar262 kPaDo not bleed a hot 235/55R18

If the door sticker and this 235/55R18 page disagree, the sticker wins.

Questions about 235/55R18

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.

Can I run 235/55R18 at a lower pressure for comfort?

Not as a habit. A soft 235/55R18 cooks the shoulders and dulls steering. Keep load index and stay on the placard.

Is the sidewall number correct for 235/55R18?

No. Sidewall PSI or kPa is a maximum for the carcass. Operating pressure is the door-pillar placard.

What is 235/55R18 in kPa?

241 kPa is the planning midpoint (100 kPa = 1 bar). 248 kPa is one PSI higher.

What PSI should 235/55R18 tyres be?

A SUV / crossover planning figure is about 35 psi cold (2.41 bar / 241 kPa). Confirm on the vehicle placard — two cars can share 235/55R18 and not share a sticker.

Handbook: placard · bar vs PSI · cold inflation · all sizes