I have a John Deere 8410 lawn mower and the back left tire was found just flat the other morning. I put air into it and it held air for about 30 minutes while cutting the grass before it would start going flat again. I’ve asjed advance from neighbors and I get everything from patch it, to inject stuff into it, etc. when researching online I find that it could be off the rim or maybe there is a hole. Any help would be greatly appreciated.
If it is off the rim it will not reinflate,so if it reinflates that is ruled out.
Fill it with air, run a weak stream of water on the valve stem and look for bubbles, could be loose valve core or leak at base of the stem.
I would suspect a small hole. Fill it with air, jack the back of the mower up, pull the rod at the back that allows the wheels to turn free, take a garden hose and run a weak stream of water over the tire as you roll it. A stream of bubbles will be apparent at the leak.I do not recommend using the goo inside the tire, really messy when the time to change it comes, and is a hit and miss repair.