rear tire pressure goes down to 25 or so psi if it sits 2 days or more.

Kiwicol said:

They tore theTurbo mate, you are never gonna break a bead on a tire. You can surely break a bead away from a rim, (it's a process) but you will never break a tires bead. It's made of lots of wires encased in rubber and wound into a circle. Then ends are then either pressed into each other or the bead is spiral wrapped with strong nylon line . No leverage from any tire fitting tool will break the bead wires, just not possible.
Rubber sealing surface
I used to make tires n beads n steel belts n tube's etc.

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I had a brand new tire mounted the machine made a loud pop then it did it again the machine made another loud pop what happened was the guy tore off about 4 inches off rubber with I call the bead. I took it from the tire shop and silaconed the tear on both sides and drove I till it was almost wore out.
I also bought a tire that had a nail in it but when they took it off same thing.

Dunno what happened to my 'quote' but anyway . . . Tearing rubber away from the rim area, yep you can do that absolutely, but that rubber is not the bead. The bead it steel wires encased inside that rubber. Tearing the rubber is not breaking the bead, it's tearing rubber. Just sayin . . . I attached a description of what a tires bead is, so we're all talking about the same thing.

gunpilot75 said:

Been that way since new (it's got 4700 miles now). I put 40plus into the rear and ride. come back, still 40 plus....sits a day or 2 days really and it's down to 25 psi. Never goes below that. Any idea why?

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Is the bike a Storm and if so do they come with TPMS's? I've had sealing problems with them in the past.

There really shouldn't be any bead seating problems with alloy wheels on a bike that new. My van tyres lose pressure but it's old and has steel rims which have rusted causing poor sealing on the bead. I'd be surprised if there's any corrosion on your alloy rims as yet.

The reason I say try parking the bike with the weight on the valve is that you say it doesn't lose pressure when riding, only when parked. There is far less pressure on the valve when the wheel is spinning than when left parked. I had a faulty valve on my Ford pickup once (a TPMS valve). It was fine driving it around all day, but it went flat over night when parked. Replacing the valve core didn't fix it so it was a sealing problem at the valve seat. I had it booked in at a tyre fitters to be fixed but it was going flat overnight and my compressor had broken so I had no way of pumping it up to get to the fitters next day. It was the fitter who told me to park it with the weight off the valve and that would slow the leak. He was right. I did that and was able to drive it next morning.

See if you can screw in the valve within the stem. If it’s a hair loose…..

Those slow leaks can be hard to find. I have a couple going on now. Soap and water will work, with lot's of patience. The last new Bridgestone I carefully mounted a couple months ago, has a small leak somewhere. Takes a couple weeks to go down, so I just air it before I ride, and say screw it. Changing these rear tires is a bit too much for this 75 year old fart! Ha!