damn i have the same wheels and my stock caps snapped right in without anything them, they are actually a pain in the ass to even get them out , they are nice and snug..oh well lol. OP car looks so much better now!
that is pretty strange. My center caps were definitely too short to make that happen. taping them as suggested would be my only option to make the stock ones fit the teeth aren't long enough to reach the thread which they would snap into