For the first 5k miles of i3 BEV ownership, I inflated all tires to 10 psi over the recommended pressure which put the pressure of the rear tires at the sidewall maximum pressure of 51 psi and the front tires at 43 psi. After 5k miles, I measured the tread depth at 3 locations across the width of each tire, inside, center, and outside. Tread wear was uniform across the width of each tire, so I did not measure any increased wear in the center of the tread. I think the wear pattern of radial ply tires is less sensitive to inflation pressure than that of old bias ply tires.
I then reduced the inflation pressure to the recommended pressures. After another 5k miles, I will measure the tread wear again, but that hasn't happened yet. I immediately sensed that the rolling resistance of the tires was significantly greater. Our i3 did not roll as freely and was more difficult to push by hand. However, I did not quantify this difference by measuring a difference in efficiency. iRemote/BMW Connected reported a 5.5 mi/kWh average during the first 5k miles. After driving ~3k miles at the recommended inflation pressure, my average efficiency has dropped to 5.1 mi/kWh. However, I can't claim that all of this decrease was due to the reduced inflation pressure. For example, I probably used climate control more often because during the first 5k miles, I did not drive our i3 during the summers as I began doing during the current 5k mile test period.
Traction and ride quality are almost certainly reduced at higher inflation pressures. Neither of these was a problem for me However, had I needed to make an emergency stop, I might not have been able to stop in as short a distance at higher inflation pressures.
I think that higher inflation pressures protect wheels against damage when driving over a sharp pothole edge because the tires can't collapse as easily thus exposing the wheel to damage from the pothole edge. Higher inflation pressure does transfer more of the bump absorption to the suspension, but so do the aftermarket lower-height springs that some owners install. I haven't read about any suspension damage caused by these springs, so I'm not concerned about higher inflation pressure damaging the suspension.
If I don't measure any tread wear advantage running the recommended inflation pressure, I'll probably increase the inflation pressure again as I did for 15 years driving our Honda Insight without any tire or suspension damage.
2014 BMW i3 Arravani Grey, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, JuiceBox EVSE