I'm having problems with repeated flats wheel with an aero rim and a 700x38c tire. The tire is rated for 50-85 PSI. I can ride the bike at low pressure (40-50 PSI), but every time I try to go to 85 PSI it ends in disaster, because the tube goes flat overnight.

I keep getting repeated holes in the belly of the tube at around 3/4" away from the valve stem, like this:







The rim tape seems smooth to the touch around the area where I get those rips, and I don't notice any rough or spiky bits there.

Am I not installing the valve stem straight enough? Is the tube just failing at higher pressure? I'm so frustrated with the constant flats, and I hate riding at low pressure. Help a brotha out? Please?