Correct Lug Size?

[deerio]

So I bought my 320 with only 2-4 rusty lug nuts per wheel. I was going to buy a whole new set but the lug nuts I have seems to have too much resistance with application and removal.

I was thinking that the studs were 7/16" -20. However I have some new never been used 7/16"-20 nuts that won't even go a full turn without feeling like it's getting crossthreaded.

I was planning on chasing the threads with a die but would like to confirm what size and pitch the lugs truly are, thanks!

[deerio]

So just in case anyone else needs to know for future reference:

The studs ARE 7/16" - 20...

I had to chase practically every stud on all 4 hubs. Some were really rough the entire length of the stud, and others weren't too bad, but all of them needed to have a die run thru.