I have the TireMinder TM77 pressure monitoring system and am getting ready to install the transmitters the rear duals. To catch the outside tires (which are mounted with the valve stems on the inside) I added Wheelmaster 135 degree valve stem extensions which fit nicely. I do worry that the weight of the transmitter will cause the extension to move up or down which may loosen the extension on the tire valve and cause a leak. Has anyone used this setup? Any problems or successes? Appreciate your help.