Martin Motors · MM620 · PSI
Martin Motors MM620 tyre PSI
- 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
34 / 34
Catalogue mid-points, front / rear · 2.2-2.4 / 2.2-2.4 bar
32-35 psi F · 32-35 psi R · 2.2-2.4 / 2.2-2.4 bar · 231/231 kPa
PSI is the Imperial reading most UK motorists still see on garage hoses. For the Martin Motors MM620 the catalogue row is 32-35 psi front and 32-35 psi rear. A 10 °C overnight drop takes roughly 1 psi (0.07 bar) off a closed Martin Motors tyre.
Martin Motors MM620 placard versus sidewall
Sidewall PSI is a carcass maximum. Recommended operating pressure for this MM620 is the pillar sticker, near 34/34 psi.
PSI, bar and kPa
PSI-led conversions for the Martin Motors MM620 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 |
Estimated pressure by tyre size (185/65R15 and others)
Planning cold pressures for sizes often seen on a passenger car. This MM620 sample opens with 185/65R15, then 195/65R15 and 225/50R17.
| Tyre size | Front PSI | Rear PSI | Front bar | Rear bar | Front kPa | Rear kPa | Note |
|---|---|---|---|---|---|---|---|
| 185/65R15 | 33 | 33 | 2.28 | 2.28 | 228 | 228 | Small / older car |
| 195/65R15 | 34 | 34 | 2.34 | 2.34 | 234 | 234 | Very common compact |
| 225/50R17 | 35 | 35 | 2.41 | 2.41 | 241 | 241 | Touring 17-inch |
| 225/45R17 | 35 | 35 | 2.41 | 2.41 | 241 | 241 | Sport 17-inch |
| 245/40R18 | 36 | 36 | 2.48 | 2.48 | 248 | 248 | Wide touring 18-inch |
| 215/55R16 | 34 | 35 | 2.34 | 2.41 | 234 | 241 | Slightly wider 16-inch |
| 205/60R16 | 34 | 34 | 2.34 | 2.34 | 234 | 234 | Taller 16-inch |
| 215/50R17 | 35 | 35 | 2.41 | 2.41 | 241 | 241 | Plus-size 17-inch |
How to set the MM620
- Park the Martin Motors MM620 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 MM620 is enough to feel a pull.
- Refit valve caps and reset TPMS if the handbook asks for a relearn.
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 |
Temperature drift
Roughly 1 psi per 5–6 °C. The table uses 34 psi as a 20 °C baseline for this MM620.
| 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 |
Martin Motors notes
No special Martin Motors exception: the MM620 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 Martin Motors MM620 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 Martin Motors sticker and this page disagree, the sticker wins.
Other Martin Motors models
Questions about this MM620
Front versus rear on the Martin Motors MM620?
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 PSI if I plus-size toward 225/50R17?
Keep load index at or above OEM. Low-profile sizes usually stay at or slightly above the placard. Use 185/65R15, 195/65R15 and 225/50R17 as a planning band.
Is the sidewall number correct on a Martin Motors MM620?
No. Sidewall PSI is a maximum. The MM620 placard is the operating target, near 32-35/32-35 psi.
How often should I check a MM620?
Monthly, before a long trip, and after a 10 °C weather swing. Include a full-size spare.
What is that in bar and kPa for the MM620?
Mid-points are about 2.31 bar (231 kPa) front and 2.31 bar (231 kPa) rear.
Handbook: placard · bar vs PSI · front vs rear · cold inflation