What would cause my 2 front tires to be slowly leaking air?

Since it's both, it is likely that the bead sealer has a leak, perhpas the tires got pretty flat over the winter and the way they were stored broke the seal.

It is not likely to be two valve leaks or two slow punctures.

Take it back to the shop and ask them to refit them to the rims.

Bad seal at the bead (where the tire meets the rim)

Bad valve ......either the internal screw in the middle , or the base where the valve goes into the rim.

Or a small puncture .

submerging the tire and rim in water is really the only way to tell..

Real soapy water in a spray bottle will show the air bubbling sometimes from the areas.

Usually a tire shop will have to take the rim off the car and set it down in a tub of water to find the small air bubbles leaking.

It could be many different things depending on "What happened to them" while they were in storage or when they were off your vehicle. It sounds to me like a cheap and easy fix. Not expensive. Most of this you can do yourself. First, fill the tires up with air and see if you can FEEL or HEAR the air and MARK the spot with a crayon. Second, check the whole tire to see if you see any metal wire, screw, nail, or anything that looks like a HOLE and MARK the spot. Third, apply some soapy water mixture around the tire area, valve stem, and rim. If you see air bubbles then MARK the spot. Lastly, dunk and hold the entire tire and rim under water and look for air bubbles. Either the tire will need a PLUG, a NEW VALVE STEM, or just REMOVED FROM THE RIM and PUT BACK ON. Costs $10.00 to $40.00 both tires

A couple different things coule be causing them to leak. Cracks in the valve stems, or in the sidewall. The valve stem core could be loose, and needs to be tightened.

Some tires have a bar code sticker around where the rim meets the tire so it doesn't always seal.

The rims themselves might have slight bends in them so they aren't sealing properly.

If you've got the time and patience, you can always take the tires off, and dunk them in a large container of water. Any leaks'll quickly become apparent. =)

I'm not a tire expert or car expert but the first thing I would do is just inspect your tires, a slow leak is usually caused by a puncture, it could be a nail or thorn still in your tire.

I would first just go to wal-mart or something and get that Slime tire sealant. http://www.slime.com/product/74/Tire-Sealant.html

It's really easy to use and if anything is punctured it should usually fix it... just squeeze it in with the tube and drive around for 10 minutes or so. It's not a permanent fix but it's cheap.

I doubt you would need new stems... but if the slime doesn't help I would then get it checked out.

new valve stems or they didnt seal a round bead of tire after you fil them throw some soapy water on tires and watch for bubbles easy to find that or just go a head an d go back to where you had them mounted at have them check

ur rims might be dented- did u maybe hit a pothole? The same thing happened to me and when i took it to the tire place- the inside of my rim had the SMALLEST little nook in it- and because of that- my tire had a really slow leak.

Bring your car to Walmart, for $9.50 per tire they will repair them

If they can not repair them, NO CHARGE