Proton · 418 · Bar
Proton 418 bar chart (2.2-2.4 / 2.2-2.4)
- 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
bar
2.31 / 2.31
32-35 / 32-35 psi · 231 / 231 kPa
32-35 psi F · 32-35 psi R · 2.2-2.4 / 2.2-2.4 bar · 231/231 kPa
2.3 bar is not 23 psi. On this 418 2.2-2.4 bar converts to about 32-35 psi. Use the table, not a guess. TPMS typically warns near 25 psi (about 25% below target). That is already a soft tyre, not a fill target.
Bar, PSI and kPa
Bar-led conversions around the Proton 418. 2.2-2.4 bar is not “32-35 divided by ten”.
| Bar | PSI | kPa |
|---|---|---|
| 2.07 | 30 | 207 |
| 2.21 | 32 | 221 |
| 2.28 | 33 | 228 |
| 2.31 | 33.5 | 231 |
| 2.41 | 35 | 241 |
| 2.48 | 36 | 248 |
| 2.62 | 38 | 262 |
| 2.76 | 40 | 276 |
| 3.03 | 44 | 303 |
| 3.45 | 50 | 345 |
| 4.14 | 60 | 414 |
Proton 418 placard versus sidewall
If the Proton sticker is painted over, the handbook is next. This website is a map, not a replacement VIN label.
Estimated pressure by tyre size (215/50R17 and others)
215/50R17 is the first planning size here. 225/40R18 is usually the plus-size or LT step. Keep load index at or above original equipment.
| Tyre size | Front PSI | Rear PSI | Front bar | Rear bar | Front kPa | Rear kPa | Note |
|---|---|---|---|---|---|---|---|
| 215/50R17 | 35 | 35 | 2.41 | 2.41 | 241 | 241 | Plus-size 17-inch |
| 195/65R15 | 34 | 34 | 2.34 | 2.34 | 234 | 234 | Very common compact |
| 225/40R18 | 36 | 36 | 2.48 | 2.48 | 248 | 248 | Low-profile 18-inch |
| 215/55R16 | 34 | 35 | 2.34 | 2.41 | 234 | 241 | Slightly wider 16-inch |
| 245/40R18 | 36 | 36 | 2.48 | 2.48 | 248 | 248 | Wide touring 18-inch |
| 205/55R16 | 34 | 34 | 2.34 | 2.34 | 234 | 234 | Typical mid-compact OEM |
| 225/45R17 | 35 | 35 | 2.41 | 2.41 | 241 | 241 | Sport 17-inch |
| 205/60R16 | 34 | 34 | 2.34 | 2.34 | 234 | 234 | Taller 16-inch |
Load notes
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 | 34 psi / 2.34 bar | 35 psi / 2.41 bar |
| Motorway + luggage | 35 psi / 2.41 bar | 38 psi / 2.62 bar |
How to set the 418
- Measure before the school run, not after the M25.
- Write LF / RF / RR / RL. Do not keep 418 numbers in your head.
- Add air in short bursts toward 34 psi (2.31 bar) front and 34 psi rear.
- If one corner 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 34 psi as a 20 °C baseline for this 418.
| 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 |
Proton notes
No special Proton exception: the 418 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 Proton 418 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.
A cheap gauge and a monthly habit will do more for this 418 than nitrogen upsells.
Other Proton models
Questions about this 418
Front versus rear on the Proton 418?
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 tyre pressure should a Proton 418 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.
What PSI if I plus-size toward 225/40R18?
Keep load index at or above OEM. Low-profile sizes usually stay at or slightly above the placard. Use 215/50R17, 195/65R15 and 225/40R18 as a planning band.
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 the sidewall number correct on a Proton 418?
No. Sidewall PSI is a maximum. The 418 placard is the operating target, near 32-35/32-35 psi.
Handbook: placard · bar vs PSI · front vs rear · cold inflation