what is the largest spacer size that can be used with stock length studs? and how many turns "minimum" should you have with the lug nuts in order to be able to keep it secure and safe to drive?

 

the max I would go with is 5mm. usually you would want about 7 full turns on the lugnut. there are spacers like project kics that you can bolt on to the original studs and it will come with its own studs:

 

i purchased 5mm H&R spacers and i got about 4 turns with the lugs. how safe is it to drive around with 4?

 

6 turns bare minimum. That's 9mm/0.75 diameters of thread engagement.

4 turns? Only 4 threads/6mm/half a diameter thread engagement.
I wouldn't.

 

For autocrossing, I use the 5mm spacers and wasn't comfortable using the OEM studs, so I ended up using the studs that came with the spacers.

BTW, replacing the studs it is not as easy of a task as it should be. ugh.

-D

 

What's the hub sizing for S2000?
I tried on some 25mm spacers I had laying around the house and the S2k hub bore is tinyyyyy.

With any bolt-on spacers you're gonna want to run hubrings.

 

73mm front and 65mm rear

 

Cool beans.
btw, s2k thread/pitch is 1.5x12, right?
My 1.25x12 lugnuts wouldn't fit

 

Yes.

12x1.25 are for Nissan, Subaru, Infiniti.

 

the minimum i would do would be the diameter of the stud. for example, if the stud is 12mm in diameter, the lug would have to go at least 12mm onto the stud.