Here you can select all the iPSW files you need to install on your iPad Device.
The latest ios firmware ipsw files are given and you can download any beta version of the software for all iPad Models if needed. Please note that it is free and does not require a jailbreak, developer ID or a UDID .Just tap on the Download button and download will start.
Also the latest updated ios 12 beta ipsw files for iPad Models are updated regularly.
Just open the Firmware version. Scroll down and select your Model to start downloading the .ipsw firmware.