Caterham · Seven 420 · Rear
Caterham Seven 420 rear tyre pressure
- 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 rear
34
2.31 bar · 231 kPa at the rear axle
32-35 psi F · 32-35 psi R · 2.2-2.4 / 2.2-2.4 bar · 231/231 kPa
Loaded Seven 420 rears often need the sticker’s second column, not a copy of the front 32-35 psi figure. A 10 °C overnight drop takes roughly 1 psi (0.07 bar) off a closed Caterham tyre.
Caterham Seven 420 placard versus sidewall
If the Caterham sticker is painted over, the handbook is next. This website is a map, not a replacement VIN label.
Estimated pressure by tyre size (225/50R17 and others)
If your Caterham Seven 420 no longer wears the OEM diameter, start at the row nearest 225/50R17 or 205/60R16 and confirm with the tyre maker’s load table.
| Tyre size | Front PSI | Rear PSI | Front bar | Rear bar | Front kPa | Rear kPa | Note |
|---|---|---|---|---|---|---|---|
| 225/50R17 | — | 35 | — | 2.41 | — | 241 | Touring 17-inch |
| 205/60R16 | — | 34 | — | 2.34 | — | 234 | Taller 16-inch |
| 185/65R15 | — | 33 | — | 2.28 | — | 228 | Small / older car |
| 215/50R17 | — | 35 | — | 2.41 | — | 241 | Plus-size 17-inch |
| 245/40R18 | — | 36 | — | 2.48 | — | 248 | Wide touring 18-inch |
| 215/55R16 | — | 35 | — | 2.41 | — | 241 | Slightly wider 16-inch |
| 205/55R16 | — | 34 | — | 2.34 | — | 234 | Typical mid-compact OEM |
| 225/40R18 | — | 36 | — | 2.48 | — | 248 | Low-profile 18-inch |
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 |
A family passenger car with a boot full of luggage should use the laden rear figure if Ford, VW or Mercedes printed one. Otherwise the modest steps in the load table are only a sketch for this Seven 420.
How to set the Seven 420
- Measure before the school run, not after the M25.
- Write LF / RF / RR / RL. Do not keep Seven 420 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.
PSI, bar and kPa
PSI-led conversions for the Caterham Seven 420 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 Seven 420.
| 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 |
Caterham notes
No special Caterham exception: the Seven 420 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 Caterham Seven 420 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 Caterham sticker and this page disagree, the sticker wins.
Other Caterham models
Questions about this Seven 420
Front versus rear on the Caterham Seven 420?
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.
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 Caterham Seven 420?
No. Sidewall PSI is a maximum. The Seven 420 placard is the operating target, near 32-35/32-35 psi.
What is that in bar and kPa for the Seven 420?
Mid-points are about 2.31 bar (231 kPa) front and 2.31 bar (231 kPa) rear.
What PSI if I plus-size toward 185/65R15?
Keep load index at or above OEM. Low-profile sizes usually stay at or slightly above the placard. Use 225/50R17, 205/60R16 and 185/65R15 as a planning band.
Handbook: placard · bar vs PSI · front vs rear · cold inflation