My truck a 1998 Chevy blazer has been sitting for the past 4 years and I just noticed that the tires are completely flat why all of a sudden unless someone punctured them
all tires will always lose air over time. thats why its important to check your tire pressure. your tires will also lose pressure in cold weather. your tires will even gain pressure as you are driving and they heat up. they will go back down as the tire cools.
The tires are junk now anyway, but tires lose air over time.
Sitting for four years and “suddenly completely flat” are mutually exclusive.
Did you monitor their air pressure on an ongoing basis over the past four years?
If not, then they did not “suddenly” go flat.
If those tires are more than 7 years old, they are now junk–even if they hadn’t lost pressure,
It can start with a slow loss over time but once it gets to a certain low pressure, the tire no longer seals very well against the the wheel. Then air is lost faster until they are flat. You can probably inflate them again if you can get a decent seal against the rim but likely you won’t without cleaning the rim. But like said if you are planning to drive it, you need new tires anyway.
If your premise correct, you are absolutely right, there’s no other explanation than someone or something punctured or otherwise let the air out of all four tires.
How often did you look at the inthe last 4 years? As every one else including me says they will lose pressure over time the more time without inflating them the faster they lose air.
That’s why if you drive on a tire that’s down to 15# or less, you are likely to create a loss of the seal between the tire and the rim, and it will go flat because of the flex.