Lawnmower tyre keeps deflating even after replacing

[Harry Bloomfield]

I thought you could tell by the valve. Tubeless have a big rubber seal, and tubed a screw down metal collar

Not the modern tubes, they just have the rubber poking through, then the brass at the end.

 

[lostinthelight]

.

 

[Mottie]

Tighten the valve core!

 

[robinbanks]

Well, perhaps first take the valve core out and check there isn't something stuck in it before you tighten it to oblivion and damage the seal (further)

And object lesson of the day; a bit of spit on your finger and wiped over the valve so it forms a skin of spit over the hole will let you see if the valve is leaking or not - a check worth doing whenever you interact with a valve

Also, side note, machines that operate in dirty environments are more prone to end up with crap in the entrance to the valve, which is then blown in when inflating. If the vehicle has ever been operated without its valve cap, perhaps place the the airline near the valve entrance but not over it and blow some air round to clear the valve before fitting the hose to it proper and inflating the tyre..

 

[Mottie]

No valve cap - let some air out to clear any obstruction before inflating.