255/35R20 · passenger car · Bar
255/35R20 bar chart (2.55 bar planning figure)
- Size
- 255/35R20
- Class
- passenger car
- Planning PSI
- 37
- Planning bar
- 2.55
bar
2.55
37 psi · 255 kPa · not a second factory sticker
255/35R20 · 37 psi · 2.55 bar · 255 kPa — estimates. Placard wins.
A 255/35R20 C-type or LT carcass can live far above a hatchback bar figure. This page’s 2.55 bar sketch is for the passenger car class, not every car that can physically mount the tyre. Under-inflation cooks the shoulders of a 255/35R20; over-inflation wears the centre rib and bangs every cat’s eye. 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
Use the table, then set a cold gauge. 255 kPa is 100 × 2.55 bar on this size.
| Bar | PSI | kPa |
|---|---|---|
| 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 |
| 3.38 | 49 | 338 |
Estimated 255/35R20 pressure by load
Plus-sizing to 255/35R20 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 | 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 255/35R20 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 255/35R20 means
255/35R20 means a 255 millimetre section width, a sidewall that is 35 percent of that width, on a 20-inch rim. The R is radial construction.
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.
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
- Measure before the school run, not after the motorway.
- Write LF / RF / RR / RL. Do not keep 255/35R20 numbers in your head.
- Add air in short bursts toward the placard, using 37 psi only as a map.
- If one 255/35R20 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 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
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.
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.
When does TPMS warn on 255/35R20?
Direct TPMS typically flags about 25% below target — near 28 psi if you were aiming at 37. Fill to the sticker, not to the lamp.
What is 255/35R20 in kPa?
255 kPa is the planning midpoint (100 kPa = 1 bar). 262 kPa is one PSI higher.
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.
Handbook: placard · bar vs PSI · cold inflation · all sizes