275/35R18 · passenger car · Overview
Recommended pressure for 275/35R18 tyres
- Size
- 275/35R18
- Class
- passenger car
- Planning PSI
- 37
- Planning bar
- 2.55
275/35R18
37 psi / 2.55 bar
255 kPa · estimates for this size class
275/35R18 · 37 psi · 2.55 bar · 255 kPa — estimates. Placard wins.
275/35R18 is a passenger car size (275 mm section, 35 % aspect, 18-inch rim). A planning cold figure around 37 psi / 2.55 bar / 255 kPa is a starting map, not a second factory sticker. TPMS typically warns near 28 psi (about 25% below a 37 psi target). That is already a soft tyre.
What 275/35R18 means
A 275/35R18 on a passenger car is a geometry. Two cars can share the size and disagree on PSI because mass and axle split differ.
Wide rear 18-inch. Rim diameter 18 in; section 275 mm. Estimates on this page assume a typical load index for the passenger car class.
Estimated 275/35R18 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 275/35R18.
| 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
Use the table, then set a cold gauge. 255 kPa is 100 × 2.55 bar on this size.
| 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
This website maps size searches such as “275/35R18 psi”. It does not replace the VIN label. If the two disagree, the label wins.
Cars often seen on 275/35R18
These catalogue models are often seen on 275/35R18 or a close OEM neighbour. Open the vehicle chart for axle-specific PSI and bar.
How to set 275/35R18
- Park so the 275/35R18 tyres are cold (three hours, or less than about a mile).
- Read the door-pillar placard for that car — not the 275/35R18 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 275/35R18.
| 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 275/35R18 |
| 38 °C (heatwave tarmac) | 40 psi | 2.76 bar | 276 kPa | Do not bleed a hot 275/35R18 |
A cheap gauge and a monthly habit will do more for a set of 275/35R18 than nitrogen upsells.
Questions about 275/35R18
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 275/35R18 in kPa?
255 kPa is the planning midpoint (100 kPa = 1 bar). 262 kPa is one PSI higher.
Is 275/35R18 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 PSI should 275/35R18 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 275/35R18 and not share a sticker.
What is 275/35R18 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.
Handbook: placard · bar vs PSI · cold inflation · all sizes