Open parts/{your rimpack}/Scripts and find cfg file of that rim. If you can't find check SRC folder inside scripts folder and open one by one with notepad (I suggest Notepad++). Than find line in cfg :
slot 0.025 0.000 0.000 0.000 0.000 0.000 2 ; this is which the rim connects to the tyre through
Numbers may be different, but you need to adjust red numbers.
PM. me if you have more questions.
