Tube slipping

I'm having trouble with my tube slipping inside my tire. I use quality rim strips and keep the tires at the proper PSI...but... my valve stem creeps from it's 90 degree position. I'm concerned that the rim will cut the stem.

I've deflated the tube and corrected it but....it slips back!!

Any ideas on how to combat this? It happens on the front and rear tire.

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You do not need a parachute to skydive.
You only need a parachute to skydive twice.

Have you tried talc powder or baby powder on the tube and inside of the tire it helps to keep them from sticking it keeps the tire from grabbing the tube.

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norms-iron-works.tripod.com

Out here where I live goat head stickers are brutal. Over the years I adopted the trick of slime and heavy thick tubes. Maybe the thicker tubes don't move as much. Haven't had any problems. With flats or tube moving. Don't know if I can help you?

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One can do anything they set there mind to.... Do a good thing...
http://www.sdc.org/fattire/goatheads.html I get no flats..

i have had problems with the thinner tube i have specialised tube on my 49cc mb these are the thickest tubes i have ever seen i got mine for a song at a thrift store but i think there about 20 bucks a pop but well worth it my little ton is all dirt steets so flats are a problem as are my tubes slipping one thing ive noticed is on my 66cc cranbrook with coaster brakes they slip on the braking you can tell this by which way the stem is leaning might wanna check it out braking or accelerating, could help resolve the problem