A question about tire pressures, please...

Good idea, but are you aware of the stereotypes and complaints about Prius drivers already driving too slow?

 

IMO safety and common sense comes first, stereotypes and complaints can be ignored. Besides that, if you are a "slow" driver of a Prius, you should be found in the right hand lane. As long as you are not impeding traffic and going with the flow there should be no problems.

 

Julia's first comment was the "Do not seat beads above 40 psi" warning and yet that same Yokohama tire has a maximum sidewall pressure of 51 psi. I also found it strange but a non-problem since my beads were seated prior to my Prius purchase in June. (The warning is for the tire installer. That "pop" you hear as he initially inflates the new tire is the "seating of the beads".) I promptly set them to the sidewall maximum, 51 psi, although they've probably dropped a bit in two months. I personally have never managed to get any center wear on low rolling resistance tires. They seem impervious to it. I ran 60 psi on my RE92's (2000 Insight) and they still rounded off on the edges, rather than got bald in the center.

I've slowly gotten my average MPG from an initial 50 to a bit over 54. Reduced need for AC has helped hugely, since it appears to give a 5 MPG hit. Of course, impending cooler weather (Atlanta) will more than offset that by November. I was getting 74 for the last tank in the Insight but consider the additional doo-dads and space a reasonable offset for the slight increase in per-mile cost. I really look forward to driving the car.

 

You can get close to that too probably if you set it to max sidewall pressure which will make your car ride like very rough and hit pot holes harder than a sledge hammer. It will beat the car's chassis to death.
Try it. Pump them up and see if I'm wrong.

 

Did you ever get your 12V battery sorted out? less than 44 sounds like you might still be trying to constantly charge the 12V.

 

Oh no, let's not try to place any more doubts in Julia's mind, she must be so sick of the hassle that the battery swap caused her already. Tons of people doing mostly shorter trips never do better than about 44 MPG average.

Honestly I think that some people here are making Julia paranoid about her Prius (even though they have best of intentions ). First they got her thinking that a few tenths of a volt difference in the battery will turn her car to crap and then to thinking that her car will become almost uncontrollable if she increases the tires by a few psi from 35 to 40.

We have to start trying to "unparanoidize" Julia now.