An onboard wireless communication system for a vehicle, such as a tire pressure monitoring system (“TPMS”) is disclosed. The TPMS includes wheel-mounted radio frequency (“RF”) sensor/transmitters that transmit RF signals conveying tire pressure information, at least one RF relay element, and an RF receiver coupled to a TPMS processor. The RF relay element(s) relay the RF signals from the sensor/transmitters to the RF receiver to reduce the negative effect of electromagnetic field scattering caused by conductive parts of the vehicle.