255/35R20 · passenger car · PSI
What PSI for 255/35R20 tyres?
- Size
- 255/35R20
- Class
- passenger car
- Planning PSI
- 37
- Planning bar
- 2.55
psi
37
2.55 bar · 255 kPa · passenger car planning figure
255/35R20 · 37 psi · 2.55 bar · 255 kPa — estimates. Placard wins.
If someone typed “255/35R20 psi”, they want Imperial. Start near 37 psi on an unladen passenger car, then confirm the vehicle placard. Sidewall max is not the target. A 10 °C overnight drop takes roughly 1 psi (0.07 bar) off a closed 255/35R20. 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.
Estimated 255/35R20 pressure by load
These 255/35R20 load steps are ± a few PSI from 37. They are not a licence to ignore a printed second column on a van or estate.
| 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 |
PSI, bar and kPa
1 bar ≈ 14.5 psi; 1 psi ≈ 6.89 kPa. Planning midpoint for 255/35R20: 37 psi = 2.55 bar = 255 kPa.
| PSI | Bar | kPa |
|---|---|---|
| 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 |
| 48 | 3.31 | 331 |
| 49 | 3.38 | 338 |
What 255/35R20 means
A 255/35R20 on a passenger car is a geometry. Two cars can share the size and disagree on PSI because mass and axle split differ.
20-inch plus-size car. Rim diameter 20 in; section 255 mm. Estimates on this page assume a typical load index for the passenger car class.
Placard versus sidewall
If a forum says “all 255/35R20 run 37 psi”, ignore it. A Qashqai and a Golf can share a size and not share a sticker.
Cars often seen on 255/35R20
These catalogue models are often seen on 255/35R20 or a close OEM neighbour. Open the vehicle chart for axle-specific PSI and bar.
How to set 255/35R20
- Park so the 255/35R20 tyres are cold (three hours, or less than about a mile).
- Read the door-pillar placard for that car — not the 255/35R20 sidewall maximum.
- If the sticker is missing, 37 psi / 2.55 bar is only a passenger car 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 37 psi as a 20 °C baseline for 255/35R20.
| 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 255/35R20 |
| 38 °C (heatwave tarmac) | 40 psi | 2.76 bar | 276 kPa | Do not bleed a hot 255/35R20 |
A cheap gauge and a monthly habit will do more for a set of 255/35R20 than nitrogen upsells.
Questions about 255/35R20
Is the sidewall number correct for 255/35R20?
No. Sidewall PSI or kPa is a maximum for the carcass. Operating pressure is the door-pillar placard.
What PSI should 255/35R20 tyres be?
A passenger car planning figure is about 37 psi cold (2.55 bar / 255 kPa). Confirm on the vehicle placard — two cars can share 255/35R20 and not share a sticker.
Is 255/35R20 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 255/35R20 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.
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.
Handbook: placard · bar vs PSI · cold inflation · all sizes