jack that tire up, remove core.. deflate tire.
pump or garvity feed ballast liquid into tire using a piece of rubber line pushed over the valve stem. 5/16 maybee.. whatever fits your stem. then a pump. drill pump.. etc..
use a burp valve.
many people put in a concentrat like ww fluid or af first. then add water. the ballast can go in without the burp valve usually.. then hookup a water hose ( garden hose ).. and fill it hitting the burp button now and then.
when you have fluid over the top of the top of the rim, remove hose and slap valve core in. then air tire up to propper pressure.
obviously start with stem at top.. etc.
if you are tubeless and tire comes off bead/rim at deflate. you have a problem. which is why I like tubes....