235/45R17 · passenger car · Bar
Recommended bar for 235/45R17
- Size
- 235/45R17
- Class
- passenger car
- Planning PSI
- 36
- Planning bar
- 2.48
bar
2.48
36 psi · 248 kPa · not a second factory sticker
235/45R17 · 36 psi · 2.48 bar · 248 kPa — estimates. Placard wins.
A 235/45R17 C-type or LT carcass can live far above a hatchback bar figure. This page’s 2.48 bar sketch is for the passenger car class, not every car that can physically mount the tyre. A 10 °C overnight drop takes roughly 1 psi (0.07 bar) off a closed 235/45R17. Low-profile {sz} does not want a “softer” pressure to recover ride. Stay at or slightly above the car’s original placard if load index is kept.
Bar, PSI and kPa
Convert around the 235/45R17 band. 2.48 bar is about 36 psi — not 23, not 33 unless the maths says so.
| Bar | PSI | kPa |
|---|---|---|
| 2.21 | 32 | 221 |
| 2.28 | 33 | 228 |
| 2.34 | 34 | 234 |
| 2.41 | 35 | 241 |
| 2.48 | 36 | 248 |
| 2.55 | 37 | 255 |
| 2.62 | 38 | 262 |
| 2.69 | 39 | 269 |
| 2.76 | 40 | 276 |
| 2.83 | 41 | 283 |
| 2.90 | 42 | 290 |
| 2.96 | 43 | 296 |
| 3.03 | 44 | 303 |
| 3.10 | 45 | 310 |
| 3.17 | 46 | 317 |
| 3.24 | 47 | 324 |
| 3.31 | 48 | 331 |
Estimated 235/45R17 pressure by load
These 235/45R17 load steps are ± a few PSI from 36. They are not a licence to ignore a printed second column on a van or estate.
| Condition | Front (est.) | Rear (est.) |
|---|---|---|
| Driver only / unladen | 36 psi / 2.48 bar / 248 kPa | 36 psi / 2.48 bar / 248 kPa |
| Typical occupancy | 37 psi / 2.55 bar / 255 kPa | 38 psi / 2.62 bar / 262 kPa |
| Motorway + luggage (sketch) | 38 psi / 2.62 bar / 262 kPa | 39 psi / 2.69 bar / 269 kPa |
Placard versus sidewall
The sidewall of a 235/45R17 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.
What 235/45R17 means
A 235/45R17 on a passenger car is a geometry. Two cars can share the size and disagree on PSI because mass and axle split differ.
Wide 17-inch sport. Rim diameter 17 in; section 235 mm. Estimates on this page assume a typical load index for the passenger car class.
Cars often seen on 235/45R17
These catalogue models are often seen on 235/45R17 or a close OEM neighbour. Open the vehicle chart for axle-specific PSI and bar.
How to set 235/45R17
- Measure before the school run, not after the motorway.
- Write LF / RF / RR / RL. Do not keep 235/45R17 numbers in your head.
- Add air in short bursts toward the placard, using 36 psi only as a map.
- If one 235/45R17 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 36 psi as a 20 °C baseline for 235/45R17.
| Ambient | Gauge | Bar | kPa | Note |
|---|---|---|---|---|
| −5 °C (hard frost) | 33 psi | 2.28 bar | 228 kPa | Gauge reads low; do not overfill once warm |
| 0 °C | 34 psi | 2.34 bar | 234 kPa | Gauge reads low; do not overfill once warm |
| 8 °C (UK winter morning) | 35 psi | 2.41 bar | 241 kPa | Gauge reads low; do not overfill once warm |
| 20 °C (set cold here) | 36 psi | 2.48 bar | 248 kPa | Baseline for this size sketch |
| 30 °C | 38 psi | 2.62 bar | 262 kPa | Do not bleed a hot 235/45R17 |
| 38 °C (heatwave tarmac) | 39 psi | 2.69 bar | 269 kPa | Do not bleed a hot 235/45R17 |
Keep 235/45R17 on the printed band for that car; 36 psi is a size sketch, not a second VIN label.
Questions about 235/45R17
Can I run 235/45R17 at a lower pressure for comfort?
Not as a habit. A soft 235/45R17 cooks the shoulders and dulls steering. Keep load index and stay on the placard.
Is 235/45R17 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.
What is 235/45R17 in kPa?
248 kPa is the planning midpoint (100 kPa = 1 bar). 255 kPa is one PSI higher.
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 235/45R17 in bar?
36 psi is 2.48 bar. Add a tenth of a bar if the placard’s laden column is higher, which is common on vans that wear this size.
Handbook: placard · bar vs PSI · cold inflation · all sizes