235/55R18 · SUV / crossover · PSI
235/55R18 PSI chart (35 psi planning figure)
- Size
- 235/55R18
- Class
- SUV / crossover
- Planning PSI
- 35
- Planning bar
- 2.41
psi
35
2.41 bar · 241 kPa · SUV / crossover planning figure
235/55R18 · 35 psi · 2.41 bar · 241 kPa — estimates. Placard wins.
If someone typed “235/55R18 psi”, they want Imperial. Start near 35 psi on an unladen SUV / crossover, then confirm the vehicle placard. Sidewall max is not the target. Under-inflation cooks the shoulders of a 235/55R18; over-inflation wears the centre rib and bangs every cat’s eye.
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.
| Condition | Front (est.) | Rear (est.) |
|---|---|---|
| Driver only / unladen | 35 psi / 2.41 bar / 241 kPa | 36 psi / 2.48 bar / 248 kPa |
| Typical occupancy | 35 psi / 2.41 bar / 241 kPa | 37 psi / 2.55 bar / 255 kPa |
| Motorway + luggage (sketch) | 36 psi / 2.48 bar / 248 kPa | 38 psi / 2.62 bar / 262 kPa |
PSI, bar and kPa
Convert around the 235/55R18 band. 2.41 bar is about 35 psi — not 23, not 33 unless the maths says so.
| PSI | Bar | kPa |
|---|---|---|
| 31 | 2.14 | 214 |
| 32 | 2.21 | 221 |
| 33 | 2.28 | 228 |
| 34 | 2.34 | 234 |
| 35 | 2.41 | 241 |
| 36 | 2.48 | 248 |
| 37 | 2.55 | 255 |
| 38 | 2.62 | 262 |
| 39 | 2.69 | 269 |
| 40 | 2.76 | 276 |
| 41 | 2.83 | 283 |
| 42 | 2.90 | 290 |
| 43 | 2.96 | 296 |
| 44 | 3.03 | 303 |
| 45 | 3.10 | 310 |
| 46 | 3.17 | 317 |
| 47 | 3.24 | 324 |
What 235/55R18 means
235/55R18 means a 235 millimetre section width, a sidewall that is 55 percent of that width, on a 18-inch rim. The R is radial construction.
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.
Placard versus sidewall
The sidewall of a 235/55R18 may say 51 psi or 350 kPa. That is a carcass maximum. Operating pressure is the tyre-information placard on the driver’s door pillar.
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.
How to set 235/55R18
- Park so the 235/55R18 tyres are cold (three hours, or less than about a mile).
- Read the door-pillar placard for that car — not the 235/55R18 sidewall maximum.
- If the sticker is missing, 35 psi / 2.41 bar is only a SUV / crossover planning figure for this size.
- Set all four with a calibrated gauge. A 3 psi miss on one corner shows up as a wander.
- 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.
| Ambient | Gauge | Bar | kPa | Note |
|---|---|---|---|---|
| −5 °C (hard frost) | 32 psi | 2.21 bar | 221 kPa | Gauge reads low; do not overfill once warm |
| 0 °C | 33 psi | 2.28 bar | 228 kPa | Gauge reads low; do not overfill once warm |
| 8 °C (UK winter morning) | 34 psi | 2.34 bar | 234 kPa | Gauge reads low; do not overfill once warm |
| 20 °C (set cold here) | 35 psi | 2.41 bar | 241 kPa | Baseline for this size sketch |
| 30 °C | 37 psi | 2.55 bar | 255 kPa | Do not bleed a hot 235/55R18 |
| 38 °C (heatwave tarmac) | 38 psi | 2.62 bar | 262 kPa | Do not bleed a hot 235/55R18 |
A cheap gauge and a monthly habit will do more for a set of 235/55R18 than nitrogen upsells.
Questions about 235/55R18
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.
What is 235/55R18 in bar?
35 psi is 2.41 bar. Add a tenth of a bar if the placard’s laden column is higher, which is common on vans that wear this size.
What is 235/55R18 in kPa?
241 kPa is the planning midpoint (100 kPa = 1 bar). 248 kPa is one PSI higher.
Is 235/55R18 the same as a plus-size swap?
Only if that is the size you fitted. Overall diameter should stay close to OEM. Pressure still follows the car, with load index at or above original.
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.
Handbook: placard · bar vs PSI · cold inflation · all sizes