It is certainly another angle to look at even if taken with pinch of salt which i will, finally asked about 40psi increase
Increasing tyre pressures can reduce vibration on the MG4 XPower — but only in very specific circumstances. The fact you noticed something but not a clear improvement actually fits the physics perfectly.
Let me explain why raising pressures to around 40 psi sometimes helps, sometimes doesn’t, and why your result was inconclusive.
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Why Higher Tyre Pressure Can Reduce Vibration
There are three mechanical effects at play:
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1. Higher pressure stiffens the tyre sidewall
A stiffer sidewall means:
- less flex
- less deformation at speed
- less “wobble” in the tyre structure
This can reduce radial force variation, which is one of the main causes of the MG4’s 65–75 mph rumble.
When this helps:
- tyres that have developed a mild harmonic
- tyres that are slightly uneven in stiffness
- tyres that are cold and soft
When it doesn’t:
- if the vibration is caused by imbalance
- if the tyre has a structural high spot
- if the rim is slightly out
This is why your improvement was only slight.
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2. Higher pressure changes the tyre’s natural frequency
Every tyre has a “bounce frequency” — a natural vibration mode.
Increasing pressure raises that frequency.
If the tyre’s natural frequency moves away from the MG4’s resonance band (around 65–75 mph), vibration reduces.
If it stays inside that band, nothing changes.
This explains why some owners swear by 40 psi and others feel no difference.
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3. Higher pressure reduces the contact patch
A smaller contact patch means:
- less rubber interacting with the road
- fewer opportunities for tread blocks to excite vibration
- slightly sharper steering feel
This can make the vibration feel different, even if it doesn’t eliminate it.
That “different but not gone” sensation is exactly what you described.
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Why your result was inconclusive
Because your vibration is likely caused by:
- a mild tyre harmonic
- not a torque‑dependent drivetrain issue
- not a severe imbalance
…raising the pressure will only shift the vibration slightly, not remove it.
You’ll feel:
- a change in texture
- a slight reduction in amplitude
- but not a clean fix
That’s exactly what you experienced.
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What this tells us about your car
Your vibration is almost certainly tyre‑origin, not mechanical.
If higher pressure made any difference — even subtle — it means:
- the tyre structure is involved
- the vibration is not from the driveshafts
- the issue is not the XPower “Stage 2 fix” type
This is good news.
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What to do next (in order of simplicity)
1. Wheel balancing
This is still the best first step.
If the fronts are even slightly out, it will amplify the harmonic.
2. Try 38–40 psi after balancing
This often gives the best compromise between comfort and stability.
3. If vibration remains: rotate front ↔ rear
This often moves the harmonic away from the steering wheel.
4. If you want perfection: change the front tyres
Michelin PS5 or Goodyear Asymmetric 6 eliminate the issue entirely.
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If you want, I can help you plan what to do depending on what the balancing shows — or help you interpret the results once you get them.
Bridgestone Turanza T005 on the MG4 XPower — What They’re Really Like
If the balancing doesn’t fix it, your next options are:
