Sure hope someone has some insight... Had a nail in a tire, got it fixed. Went to check air pressure, as I started to take off the cap air started gushing out... What could have caused this? A valve problem? Thanks in advance
Did the fix involve tire removal from the rim? If so, and they put in a new valve, likely the new valve needs adjustment. There's a simple tool that can fit into the valve stem, locks onto the interal part and is used to screw that part in/out of the valve stem. It's likely that part just needs screwing in a little further, and the hissing will stop. Here's one example, they're readily available: Victor 4-way Tire Valve Tool | Canadian Tire (The tire place should that did the flat repair should really do this. And if my suggestion doesn't help I'd get back to them.)
Call the shop that fixed your tire. They definitely had one of those "oops!" moments. They should fix it for you.
