The valve is the least likely issue. They may be dry rotted, which is noticeable by cracks in the rubber. There could also be a bead blend. Aluminum rims will always suffer from this. The easiest way to identify the problem is to remove the wheel from the vehicle, fill it to the specified pressure and spray it down with soapy water. The leak will create bubbles. If it's due to a crack, the tire is junk but if the leak is between the rim and tire the rim can be cleaned up and the tire remounted.

If there is a valve in the tire, it shouldn't be leaking from there. Ten year old tires are old. They have cracks you may not be able to see. If you have a large pool of water, take the tire and dunk it vertically and see if any air comes out.

The seal between the tire and the wheel has failed because the wheel has dried out. Take the tires to a shop and have them deflate and reseal them to the rim. You can't do it because once you let all the air out of tires you will not be able to get them to expand to fit the wheel without a tire machine. Depending on how the tires were stored they may not be any good anyway. Look at the side wall and see if you see small lines that indicate cracking if you do the tire will fail on you.

Hi the issue is sunlight actually it gets in every where and it breaks down the cells of the ribber within the tires. so they have perished.

ten year old tires regardless of storage are toast.. tires dry rot in less than five years.. now if you TRY to take them into a shop they most likely will turn you away due to they may explode.. then you put them on the car and they WILL explode soon enough..

forget it

I have tires that were stored in my friend's garage for about ten years.(with rims) they have 80% tread life left. But yesterday i filled them up with air and they lost air in a day. Is it just bcz they are old or bcz they might have some issue with valve?