Flat tires

[1964-M20E]

I have had two flat tires in the two months on the main gear one left and one right the cause has been the valve stems breaking.  The mechanic says it could be the tires (condors) slipping on the rims.  Anyone else have this problem?  Tire pressures have been good.  The previous owner put the tires on about 2.5 years ago a year before I bought the plane. 

Also for the pre J models are you using a straight valve stem or a 90 degree angled valve stem?

 

The good thing both have been there waiting for me before I went flying.

[stevesm20b]

I had the same problem with a straight valve stem breaking shortly after buying my aircraft.. I think it broke because every time you put air in your tire you have to pull the stem out away from the hub. The previous owner may have pulled the stem out and caused it to crack. I went to the 90 degree valve stem. The tubes with the 90 degree valve stems cost twice as much as the straight ones.