255/35R20 · passenger car · Overview
255/35R20 tyre pressure
- Size
- 255/35R20
- Class
- passenger car
- Planning PSI
- 37
- Planning bar
- 2.55
255/35R20
37 psi / 2.55 bar
255 kPa · estimates for this size class
255/35R20 · 37 psi · 2.55 bar · 255 kPa — estimates. Placard wins.
255/35R20 is a passenger car size (255 mm section, 35 % aspect, 20-inch rim). A planning cold figure around 37 psi / 2.55 bar / 255 kPa is a starting map, not a second factory sticker. 20-inch plus-size car. 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.
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.
Estimated 255/35R20 pressure by load
Load moves the rear first on a passenger car. If the factory placard already has a laden column, use that — not this sketch for 255/35R20.
| 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 |
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 |
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
- 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.
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.
What is 255/35R20 in kPa?
255 kPa is the planning midpoint (100 kPa = 1 bar). 262 kPa is one PSI higher.
Handbook: placard · bar vs PSI · cold inflation · all sizes