Tires: air loss in goodyear tires, goodyear tires, aluminum rims

Question
about 3-4 years ago i bought 4 goodyear tires, medium price, for my 2001 pontiac gtp.  it has aluminum rims.  i live in minnesota so it does get kind of chiily here.  every since i bought these tires they have lost approx. 5 to 10 pounds of air every two weeks.  the tires they replaced were the eagles but i didn't want that expensive a tire since i don't do high performance driving.  i keep the car parked in the garage, winter and summer.  in the summer the air loss is only about 5 pounds but still a loss and on a regular basis.  any ideas?  i don't want to go back to the dealer as he'll just soak me for either advice or new tires.

Answer
Bob,

It might not be the tires.  It might be the rims.  

It is common for there to be a bit of corrosion in the interface between the tire and the rim.  But you need to be sure in order to know what your next step should be.

You need to immerse the tire and wheel assembly to see where the leaks are.  I've used a large sink, but I have heard of people using a kiddy wading pool.  Just remember that the assembly will float so you need to get some bricks to weigh it down.

You are looking for small leaks, so patience will be rewarded.  Also, leaks THROUGH the aluminum are not unheard of and they will look more like little tiny bubbles forming in the surface of the wheel, more like carbonated soda.