Martin Motors · MM520 · Rear
Rear axle PSI and bar on the Martin Motors MM520
- 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 MM520 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 Martin Motors tyre.
Martin Motors MM520 placard versus sidewall
Sidewall PSI is a carcass maximum. Recommended operating pressure for this MM520 is the pillar sticker, near 34/34 psi.
Estimated pressure by tyre size (235/35R19 and others)
Planning cold pressures for sizes often seen on a passenger car. This MM520 sample opens with 235/35R19, then 275/35R18 and 225/40R18.
| Tyre size | Front PSI | Rear PSI | Front bar | Rear bar | Front kPa | Rear kPa | Note |
|---|---|---|---|---|---|---|---|
| 235/35R19 | — | 36 | — | 2.48 | — | 248 | Front 19-inch |
| 275/35R18 | — | 37 | — | 2.55 | — | 255 | Wide rear |
| 225/40R18 | — | 35 | — | 2.41 | — | 241 | Front 18-inch |
| 225/45R17 | — | 35 | — | 2.41 | — | 241 | Front sport size |
| 275/30R19 | — | 37 | — | 2.55 | — | 255 | Rear 19-inch |
| 245/40R18 | — | 36 | — | 2.48 | — | 248 | Square-ish sport |
| 255/35R18 | — | 36 | — | 2.48 | — | 248 | Rear stagger 18-inch |
| 255/40R17 | — | 36 | — | 2.48 | — | 248 | Rear stagger 17-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 | 34 psi / 2.34 bar | 35 psi / 2.41 bar |
| Motorway + luggage | 35 psi / 2.41 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 MM520.
How to set the MM520
- Park the Martin Motors MM520 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 MM520 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 Martin Motors MM520 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 MM520.
| 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 MM520 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 MM520 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 MM520 than nitrogen upsells.
Other Martin Motors models
Questions about this MM520
Front versus rear on the Martin Motors MM520?
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 MM520?
Mid-points are about 2.31 bar (231 kPa) front and 2.31 bar (231 kPa) rear.
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 235/35R19, 275/35R18 and 225/40R18 as a planning band.
What tyre pressure should a Martin Motors MM520 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.
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