Best Tire Pressure? on Lowered Prius

What Psi do you guys run on aftermarket wheels and suspensions? Did you guys try different Psi? What are the difference in ride quality and mpg that you have experienced?

After some hard work and a case of beer, I have managed to install lowering springs and sway bar on my Prius. So far I have driven about 250 miles on the new setup. I have tested tire pressure at 50/48 and 42/40psi so far on the Michelin MXM4s. 50 psi was way too rough of a ride so I back it all the way to 40, and now the car rides a little "too smooth" I don't know how to explain it, but it is smooth in a bad way? Going to go up to 45/43 tomorrow and take a joy ride.

Just took the on ramp at 55mph today (dusted a tailgating Mustang off my bumper he gave me a thumbs up as he passed me on the freeway) and the car felt great, minimum body roll with a little tire slip (traction light winked at me) at the turn exit (Due to inexperience driving the Prius I think). I don't think I will need to add any more braces for now, something in the back of my head strikes a little fear in me while taking that ramp "It's still a Prius, it doesn't have enough to power out of a slide, you gonna slide off the road!"

 

Agreed, I just haven't driven too many passenger cars besides the Civic that my wife had. At 50 psi, the Prius still felt alot better than my previous cars and it keeps me confident in the daily rain that we have here. I've just been spoiled since I got the Prius, to me it feels like a luxury sedan compare to the roadsters that I had before. So I really don't know what is good practice to keep on a daily basis. Perhaps I should have worded my question a little better.

What is a good Psi for a good balanced tire wear, suspension life, MPG etc.? I don't normally drive aggressively, I just like to have some seldom fun.

 

Thanks, gonna increase to mid 40's tomorrow. I guess I like to feel the road a little, with the Prius steering I already don't feel like I'm "driving" With tire pressure at 40 the car is very smooth but felt a little heavy at the turns if that makes sense. I'm bad at describing I'll do some trial and error, I'm sure I can get it just right sooner or later.

 

I was on a 55 mpg displayed tank before I did the install, my Fuelly is usually -2 compared to the display. I'm back at 50 mpg display after a few joyrides. I hate feeling guilty while having a little fun on the road The temps here swings much in the Spring. Low 40s in the morning and late night and 70s in the afternoon. I don't mind the rough rides at all, but something just didn't feel right with the 50psi and the new suspension. I think you are right F8L, the car is skipping over imperfections on the road. At 40 psi, to me the car lacks road feel. Mid 40s psi should bring me to a happy medium, we'll see. This is like trying to pick a perfect pair of running shoes. Minimalist is too hard on the feet and traditional ones feels too cushy makes my feet fall asleep. I am turning into quite an anal person with the Prius

 

I've put the rattles out of my mind after I read numerous complains on PC (it is normal even in a new car). I try not to cause any additional rattle myself but gave up on locating and stopping every little rattle that only happens in certain road conditions.