whats the thread size on stock size studs?

[tonys87]

here is the problem i bought some wheel adapters for the grand national off ebay.. they are 5x4.75 to 5x4.75 and have 12mm 1.5 inch studs, they also came with the needed lug nuts to hold down the adapter. evrything went on perfect till i went to mount the gta wheel with the studs that i already had the wheels mounted on(before the adapter with spacer).. but they wont screw on properly on to the adapter but were fine on the studs on the car... whats the deal. i wanna get this right, the last thing i need is a wheel flying off. so here are some questions i need answered..

what the thread size on the GN'S
do they have 12mm lug nuts with the extra thread on the outside for the plastic covers? thanks

 

[pacecarta]

gm GN lug threads are metric 12mm x1.5 (thread pitch ...not length)

if the studs on the adapter are 12mm 1.5 then the lug nuts you took off the car should have fit the adapter

pre 82 the 5x 4.75 pattern was available with sae 7/16-20 threads
what do you have on the car ?
(theres also a 12mm 1.25 that most smaller gm and imports use but that size shouldnt be on a 5x4.75 pattern )

as to the second question
gm open lugs in 12mmx1.5 with the threads for the plastic twist on caps were available on many gm vehicles , the gtas used these cap style lug nuts , search ebay or kirbanperformance for the gta lug nuts

 

[tonys87]

thanks.. i just went to auto zone and compared what i needed and what i had.. diffrent sizes. glad i didnt try to just shove them in. thanks again pacecarta