235/50R18 · SUV / crossover · Overview
235/50R18 tyre pressure
- Size
- 235/50R18
- Class
- SUV / crossover
- Planning PSI
- 35
- Planning bar
- 2.41
235/50R18
35 psi / 2.41 bar
241 kPa · estimates for this size class
235/50R18 · 35 psi · 2.41 bar · 241 kPa — estimates. Placard wins.
Searches for “235/50R18 pressure” usually want a number. Use 35 psi (2.41 bar) only as a sketch; the door-pillar placard on the car that wears this size still wins. A 10 °C overnight drop takes roughly 1 psi (0.07 bar) off a closed 235/50R18.
What 235/50R18 means
235/50R18 means a 235 millimetre section width, a sidewall that is 50 percent of that width, on a 18-inch rim. The R is radial construction.
18-inch CUV. Rim diameter 18 in; section 235 mm. Estimates on this page assume a typical load index for the SUV / crossover class.
Estimated 235/50R18 pressure by load
Plus-sizing to 235/50R18 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 | 35 psi / 2.41 bar / 241 kPa |
| Typical occupancy | 36 psi / 2.48 bar / 248 kPa | 37 psi / 2.55 bar / 255 kPa |
| Motorway + luggage (sketch) | 37 psi / 2.55 bar / 255 kPa | 38 psi / 2.62 bar / 262 kPa |
PSI, bar and kPa
Convert around the 235/50R18 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 |
Placard versus sidewall
The sidewall of a 235/50R18 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 235/50R18
These catalogue models are often seen on 235/50R18 or a close OEM neighbour. Open the vehicle chart for axle-specific PSI and bar.
How to set 235/50R18
- Park so the 235/50R18 tyres are cold (three hours, or less than about a mile).
- Read the door-pillar placard for that car — not the 235/50R18 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 235/50R18.
| 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 235/50R18 |
| 38 °C (heatwave tarmac) | 38 psi | 2.62 bar | 262 kPa | Do not bleed a hot 235/50R18 |
If the door sticker and this 235/50R18 page disagree, the sticker wins.
Questions about 235/50R18
Is the sidewall number correct for 235/50R18?
No. Sidewall PSI or kPa is a maximum for the carcass. Operating pressure is the door-pillar placard.
What is 235/50R18 in kPa?
241 kPa is the planning midpoint (100 kPa = 1 bar). 248 kPa is one PSI higher.
Is 235/50R18 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.
When does TPMS warn on 235/50R18?
Direct TPMS typically flags about 25% below target — near 26 psi if you were aiming at 35. Fill to the sticker, not to the lamp.
Can I run 235/50R18 at a lower pressure for comfort?
Not as a habit. A soft 235/50R18 cooks the shoulders and dulls steering. Keep load index and stay on the placard.
Handbook: placard · bar vs PSI · cold inflation · all sizes