This paper introduces an end-to-end untethered VR system design and open platform that can meet virtual reality latency and quality requirements at 4K resolution over a wireless link. High-quality VR systems generate graphics data at a data rate much higher than those supported by existing wireless-communication products such as Wi-Fi and 60GHz wireless communication. The necessary image encoding, makes it challenging to maintain the stringent VR latency requirements. To achieve the required latency, our system employs a Parallel Rendering and Streaming mechanism to reduce the add-on streaming latency, by pipelining the rendering, encoding, transmission and decoding procedures. Furthermore, we introduce a Remote VSync Driven Rendering technique to minimize display latency. To evaluate the system, we implement an end-to-end remote rendering platform on commodity hardware over a 60Ghz wireless network. Results show that the system can support current 2160x1200 VR resolution at 90Hz with less than 16ms end-to-end latency, and 4K resolution with 20ms latency, while keeping a visually lossless image quality to the user.