Originally Posted by dirty hippie
...... I heard air coming out. It looks like the base of the stem valve has cracked and slowly leaking air....
So what are my options?
Sounds like you should replace the valve stem for sure as you have spotted a crack in the rubber; they deteriorate with sun, oil and age. May as well do all if they are about same age when appropriate to be on the safe side.
To find the precise point of the leak, soapy water solution or even spit can pinpoint the exact location via visible formation of bubbles. A hiss is sometimes tough to find, but a wet finger can sometimes feel the small cold escape of air.
If checking valve stems, where cracks may not yet be visible, and an air leak is not actually yet coming from the base of the stem, you could test with a soapy solution to see if there are any bubbles arising at the top of the stem from the small needle valve at the core.
If the needle valve is the source of the leak, you well may be able in the short term, to remove the valve inside. [using the inverted cap of an old bicycle tire cap /or small tool you could buy]. After deflating the tire, replace a new valve in the stem and save dismounting the tire. [Try and be careful with air blast releasing the valve, bleed down first, and eye protection, jackstands etc etc]
Regarding the jacking points, the Honda Insight Owners Manual, referring to 'changing a flat tire says:
"Locate the jacking point nearest
the tire you need to change. It is
pointed to by an arrow molded into
the underside of the body."
nb. Make sure to get the proper length of valve stem:
If the valve stems are overly long sticking beyond the tire, what could cause a crack prematurely is if they would be snagged on curbs when parking and bent sideways as so to crack.
[In the unlikely instance you have old school hubcaps on steel rims or somesuch , make sure the valve stem holes in the hubcaps are properly aligned with the valve stem protruding out it's hole in a hub cap and not bent.]
If valve stem is cracked, the others might not be far off so preventive maintenance might pay off.
The valve stem afaik
is replaced by being pulled from the inside out, and is something you may be able to do yourself if you have access to sufficient air pressure to re-seat the bead after breaking it and installing a new stem. Use a bit of the soapy liquid stuff they brush on. I did this with an old pickup truck tire recently because of a crack at the valve stem base as well.
There may be a DIY shop with a tire dismounting machine in your area that makes dismounting the bead easy. Their charge is $4 per tire if you do it yourself.
Be sure there's caps on all the valve stems as a first line of defense for leaking tires.