255/40R19 · passenger car · kPa
255/40R19 kPa inflation table
- Size
- 255/40R19
- Class
- passenger car
- Planning PSI
- 37
- Planning bar
- 2.55
kPa
255
2.55 bar · 37 psi · 100 kPa = 1 bar
255/40R19 · 37 psi · 2.55 bar · 255 kPa — estimates. Placard wins.
Kilopascals show up on some Asian stickers and ISO sheets. 255 kPa is the planning midpoint for 255/40R19 (2.55 bar / 37 psi). 100 kPa = 1 bar. EV 19-inch aero wheel. These rows are estimates interpolated for the size, not OEM for a named VIN. 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.
kPa, bar and PSI
1 bar ≈ 14.5 psi; 1 psi ≈ 6.89 kPa. Planning midpoint for 255/40R19: 37 psi = 2.55 bar = 255 kPa.
| kPa | Bar | PSI |
|---|---|---|
| 228 | 2.28 | 33 |
| 234 | 2.34 | 34 |
| 241 | 2.41 | 35 |
| 248 | 2.48 | 36 |
| 255 | 2.55 | 37 |
| 262 | 2.62 | 38 |
| 269 | 2.69 | 39 |
| 276 | 2.76 | 40 |
| 283 | 2.83 | 41 |
| 290 | 2.90 | 42 |
| 296 | 2.96 | 43 |
| 303 | 3.03 | 44 |
| 310 | 3.10 | 45 |
| 317 | 3.17 | 46 |
| 324 | 3.24 | 47 |
| 331 | 3.31 | 48 |
| 338 | 3.38 | 49 |
Estimated 255/40R19 pressure by load
Plus-sizing to 255/40R19 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 | 37 psi / 2.55 bar / 255 kPa | 37 psi / 2.55 bar / 255 kPa |
| Typical occupancy | 38 psi / 2.62 bar / 262 kPa | 39 psi / 2.69 bar / 269 kPa |
| Motorway + luggage (sketch) | 39 psi / 2.69 bar / 269 kPa | 40 psi / 2.76 bar / 276 kPa |
What 255/40R19 means
A 255/40R19 on a passenger car is a geometry. Two cars can share the size and disagree on PSI because mass and axle split differ.
EV 19-inch aero wheel. Rim diameter 19 in; section 255 mm. Estimates on this page assume a typical load index for the passenger car class.
Placard versus sidewall
This website maps size searches such as “255/40R19 psi”. It does not replace the VIN label. If the two disagree, the label wins.
Temperature drift
Roughly 1 psi per 5–6 °C. The table uses 37 psi as a 20 °C baseline for 255/40R19.
| Ambient | Gauge | Bar | kPa | Note |
|---|---|---|---|---|
| −5 °C (hard frost) | 34 psi | 2.34 bar | 234 kPa | Gauge reads low; do not overfill once warm |
| 0 °C | 35 psi | 2.41 bar | 241 kPa | Gauge reads low; do not overfill once warm |
| 8 °C (UK winter morning) | 36 psi | 2.48 bar | 248 kPa | Gauge reads low; do not overfill once warm |
| 20 °C (set cold here) | 37 psi | 2.55 bar | 255 kPa | Baseline for this size sketch |
| 30 °C | 39 psi | 2.69 bar | 269 kPa | Do not bleed a hot 255/40R19 |
| 38 °C (heatwave tarmac) | 40 psi | 2.76 bar | 276 kPa | Do not bleed a hot 255/40R19 |
How to set 255/40R19
- Measure before the school run, not after the motorway.
- Write LF / RF / RR / RL. Do not keep 255/40R19 numbers in your head.
- Add air in short bursts toward the placard, using 37 psi only as a map.
- If one 255/40R19 is 4 psi down, hunt for a nail before you blame the weather.
- Log date, ambient temperature and the four readings.
Cars often seen on 255/40R19
These catalogue models are often seen on 255/40R19 or a close OEM neighbour. Open the vehicle chart for axle-specific PSI and bar.
If the door sticker and this 255/40R19 page disagree, the sticker wins.
Questions about 255/40R19
Is 255/40R19 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 255/40R19 in bar?
37 psi is 2.55 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 255/40R19 in kPa?
255 kPa is the planning midpoint (100 kPa = 1 bar). 262 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.
Can I run 255/40R19 at a lower pressure for comfort?
Not as a habit. A soft 255/40R19 cooks the shoulders and dulls steering. Keep load index and stay on the placard.
Handbook: placard · bar vs PSI · cold inflation · all sizes