Based my experience using stock tyre Turanza ER370 (recommended 33 PSI front & 32 PSI rear). All good.

Once change to Ecopia EP200, 33 & 32 PSI somehow increase my fuel consumption, noisy & tyre feel like less air.

Pump up to 35 & 34 PSI. All optimized. They said EP200 compound is softer than average tyre.

For me recommended tyre pressure stated on door side or manual is for stock tyre. Good to follow.

But if change to different tyre brand / model, the optimum air pressure will be different.

Think so.

My benchmark is fuel consumption. Noise level & comfortness are subjective for me. Based on car insulation too.

By right, eco tyre should use less fuel than non eco tyre.

My understanding will be OEM tyre. Tyre originally fitted in upon purchasing the car.

I don't think same pressure applicable with tyre with same range / size. Unless exact same brand, size & model.

Eventhough same range / size, different tyre manufacturer or even different model will be using different compound, soft / hard sidewall, etc. That contribute to optimum tyre pressure.

Not so expert lah. Based on my experience & reading only.