Losing Air in All Tires!

Since the tires are only rated for 44 PSI max-cold and tires lose a little bit over time anyway, your experience is probably a realistic expectation.
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Leaky valve stems? Sabotage?

 

Same problem with my 06 Gen II. Lot's of Florida Summer heat build up during the day that eventually leaks out of hyperinflated tires. Had much better luck controlling my medium (40/38) tire pressures when I switched to a Nitrogen fill (vs 78% nitrogen regular air).

Still playing with tire pressures on my Gen III; when I find a happy PSI, I'll go for a NitroFill again.

Try Nitrogen; Good Luck.

 

I had this problem with my 2007 Prius. Everytime I check the tires they had lost some pressure. I bought a valve stim tool and checked all the valve stims. All were not fully seated. I tightened each one, but only firm. Did not over tighten and never lost any more pressure.

My 2010 seems to be ok and I don't lose any pressure. I still want to check the stims if I can find my tool.

 

The maximum cold tire inflation pressure can be found on the sidewall of the tire. Typically this is 44 psi. It might be lower or it might be higher than that number, depending upon the tire brand/model in service.

 

The sidewall value is the maximum rated cold pressure. Use more at your own risk.

 

It's possible that the place that changed your tyres last time did a bad job with the TPMS sensors, not resealing them correctly. I believe all 2006 and later models of Prius have TPMS in the US. Read Art's Automotive's article on the subject.

 

Take a squeeze spray bottle, mix up a solution of dish soap and water, spray it on the valve stems, and the beads all the way around. If you have much of a leak at all it should reveal itself by blowing soap bubbles.

5-10 psi a week is enough that you should be able to find it. I would suspect dirt or damage on the bead(s). If so you will have to remove the tires, clean the beads and the rims, and have them put back on with good bead sealer.

I had a set of Pirellies on some car once that I couldn't get them to seal on the beads, ever. I was always putting air in them.

Icarus

 

The tire shop is supposed to do that when they put new tires on. Whether they actually do, is another question

 

Yea well, the tire shop is suppose to torque the lug nuts by hand. After I got new tires on the Prius,, I went to double check the torque,, I used a 150 ft/lps 1/2 snap on clicker torque wrench. I couldn't break them. I finally put a 3' pipe cheater on a 1/2' breaker bar to get them cracked! Must have been ~250 ft/lps!

Icarus

 

51 cold max inflation pressure on my sidewall. This problem makes me want to check my air pressure on every fill up. Also the other post on the Tire Valve Core is a good reminder to get the old valve core remover out.

 

Like many things in life, if you don't do it yourself, it doesn't get done right

 

Adding to that: If you do it yourself and it gets screwed up, you know who to blame. If you aren't married, you can always blame yourself.

Tom

 

Well, to amend that: if you f*** it up, at least you did so with good intentions. Not like you went out of your way to rip yourself off, unless you have very deep and weird psychological problems

Blame the woman? See, I just KNEW there was a good reason to get married!

 

I think you're dancing on egg shells by inflating them that high. I would read the sidewall for the maximum infation pressure.. it's there. I wouldn't go over that pressure.

Now, most all tires will typically loose approx 2psi each month. If your loosing 5 to 10 psi then I believe there is an issue that may or may not be related to the high pressure you're putting in. To test, drop the pressure down to, say 46psi and see if the loss rate drops back to about 2psi per month. If it doesn't then there's a very slow leak and have each tire bubble tested.