This great sonar ranger from Devantech offers a wide range from 3cm to 3m. For further range see the SRF08. The SRF04 is interfaced using the one output line to ping the sensor and an input line to read the echo.
This is the SRF05 Ultrasonic ranger made by Devantech. The Ultrasonic detector can detect from ~4 inches to ~13 feet.
The MaxBotix low voltage MB1010 LV-MaxSonar-EZ1 offers very short to long-range detection and ranging, in an incredibly small package with ultra low power consumption. The MaxSonar-EZ1 detects objects from 0" to 254".
These large Tiller Traction Lug wheels are 13" in diameter. They come as pair and have steel 5/8" diameter shafts and bearings.
Pan and Tilt assembly for horizontal surface mount. Made using two Lynxmotion servo brackets. Perfect for your small remote piloted robot! Includes hardware.