I have a MINI 2004 and recently noticed my rear left tire keeps loosing air and go flat in one week period. I do not have flat run tires. The other three are fine. Even if it is winter season, why not the other three ? Anyone out there with same problem ? Thanks for replying back.

 

I had a similar problem on my last MINI. No nails or screws. Turned out that the wheel had a crack. Wouldn't hurt to have that checked.

 

I'd test the valve first with a little spit or some soapy water to see if that's the problem. Then around the bead. if nothing shows up you could test it in a tub of water to see where the leak is. Good luck!

 

Bring it to a tire store to check for a nail.

 

My right rear loses air too. I lose about three pounds a month while the other tires stay at 38 pounds. I tightened the valve core, but I haven't taken the tire off and put it in a tub of water - I worked at a tire store in high school. I think you should take it to a tire shop as that is a lot of air to lose in a week.

 

Get a valve stem cap that has the slotted end which is used to tighten the valve stem. Use it to check if valve is possibly loose. It does happen.
GF San Diego

 

There are many things that can cause a tire to lose air. If you can't find the source of the leak, take it to a tire shop. Chances are that it will be something you can't repair yourself and you will need their services anyway.