smart · forFour · Front
Front axle PSI and bar on the smart forFour
- Drivetrain
- front-wheel drive
- Body
- passenger car
- PSI F / R
- 32-35 / 32-35
- Bar F / R
- 2.2-2.4 / 2.2-2.4
psi front
34
2.31 bar · 231 kPa at the steering axle
32-35 psi F · 32-35 psi R · 2.2-2.4 / 2.2-2.4 bar · 231/231 kPa
A 3 psi miss on one front corner of this forFour shows up as a wander before the TPMS lamp bothers you. Target 34 psi (2.31 bar) cold. Under-inflation cooks the shoulders of a forFour; over-inflation wears the centre rib and bangs every cat’s eye.
smart forFour placard versus sidewall
Sidewall PSI is a carcass maximum. Recommended operating pressure for this forFour is the pillar sticker, near 34/34 psi.
Estimated pressure by tyre size (205/60R16 and others)
Planning cold pressures for sizes often seen on a passenger car. This forFour sample opens with 205/60R16, then 215/55R16 and 215/50R17.
| Tyre size | Front PSI | Rear PSI | Front bar | Rear bar | Front kPa | Rear kPa | Note |
|---|---|---|---|---|---|---|---|
| 205/60R16 | 34 | — | 2.34 | — | 234 | — | Taller 16-inch |
| 215/55R16 | 34 | — | 2.34 | — | 234 | — | Slightly wider 16-inch |
| 215/50R17 | 35 | — | 2.41 | — | 241 | — | Plus-size 17-inch |
| 245/40R18 | 36 | — | 2.48 | — | 248 | — | Wide touring 18-inch |
| 205/55R16 | 34 | — | 2.34 | — | 234 | — | Typical mid-compact OEM |
| 195/65R15 | 34 | — | 2.34 | — | 234 | — | Very common compact |
| 225/40R18 | 36 | — | 2.48 | — | 248 | — | Low-profile 18-inch |
| 185/65R15 | 33 | — | 2.28 | — | 228 | — | Small / older car |
Pressure against load
Load moves the rear of a passenger car first. If the factory placard already has a “laden” column, use that instead of these sketches.
| Condition | Front (est.) | Rear (est.) |
|---|---|---|
| Driver only | 34 psi / 2.34 bar | 34 psi / 2.34 bar |
| Full occupancy | 35 psi / 2.41 bar | 36 psi / 2.48 bar |
| Motorway + luggage | 36 psi / 2.48 bar | 36 psi / 2.48 bar |
Steering feel on the forFour lives on this axle. Do not drop front pressure to “soften” a plus-size 215/50R17; you will roll the sidewall in a roundabout.
How to set the forFour
- Park the smart forFour for at least three hours (cold tyres).
- Use a calibrated gauge, not the only meter on a forecourt hose.
- Set the placard for that axle — about 32-35 psi / 2.2-2.4 bar front and 32-35 psi / 2.2-2.4 bar rear on this catalogue row.
- Recheck all four. A 2 psi miss on a front-wheel drive forFour is enough to feel a pull.
- Refit valve caps and reset TPMS if the handbook asks for a relearn.
PSI, bar and kPa
PSI-led conversions for the smart forFour band (32-35 / 32-35).
| PSI | Bar | kPa |
|---|---|---|
| 30 | 2.07 | 207 |
| 32 | 2.21 | 221 |
| 33 | 2.28 | 228 |
| 33.5 | 2.31 | 231 |
| 35 | 2.41 | 241 |
| 36 | 2.48 | 248 |
| 38 | 2.62 | 262 |
| 40 | 2.76 | 276 |
| 44 | 3.03 | 303 |
| 50 | 3.45 | 345 |
| 60 | 4.14 | 414 |
Temperature drift
Roughly 1 psi per 5–6 °C. The table uses 34 psi as a 20 °C baseline for this forFour.
| Ambient | Gauge (front mid) | Bar | kPa | Note |
|---|---|---|---|---|
| −5 °C (hard frost) | 31 psi | 2.14 bar | 214 kPa | Gauge reads low; do not overfill once warm |
| 0 °C | 32 psi | 2.21 bar | 221 kPa | Gauge reads low; do not overfill once warm |
| 8 °C (UK winter morning) | 33 psi | 2.28 bar | 228 kPa | Gauge reads low; do not overfill once warm |
| 20 °C (set cold here) | 34 psi | 2.34 bar | 234 kPa | Baseline |
| 30 °C | 36 psi | 2.48 bar | 248 kPa | Do not bleed a hot tyre |
| 38 °C (heatwave tarmac) | 37 psi | 2.55 bar | 255 kPa | Do not bleed a hot tyre |
smart notes
No special smart exception: the forFour uses the door-pillar placard. Size estimates on this page only help if you have left the original load index behind.
Spare and inflator kit
A matching full-size spare on the smart forFour usually follows the higher axle (often the rear, near 32-35 psi). A space-saver is commonly 60 psi / 4.1 bar — read that tyre’s own sidewall. An inflator kit is not a spare; check the sealant date.
If the smart sticker and this page disagree, the sticker wins.
Other smart models
Questions about this forFour
Front versus rear on the smart forFour?
This row is 32-35 F / 32-35 R. Even when they match, a laden rear can justify a higher number if the sticker prints one.
What is that in bar and kPa for the forFour?
Mid-points are about 2.31 bar (231 kPa) front and 2.31 bar (231 kPa) rear.
What tyre pressure should a smart forFour use?
Catalogue reference is 32-35 psi front and 32-35 psi rear (2.2-2.4 / 2.2-2.4 bar), cold. Confirm on the door-pillar placard.
Is the sidewall number correct on a smart forFour?
No. Sidewall PSI is a maximum. The forFour placard is the operating target, near 32-35/32-35 psi.
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 · front vs rear · cold inflation