How important is it to run these? I have 9" 6ULs and RS3 tires with 949 aluminum wheel nuts. Do I need to run the longer studs or not?

 

A general rule for aluminum, you want 1.5-2 times the diameter of the shank worth of engagement. So an M12 stud wants 18-24 mm engagement, which for a 1.5 thread pitch means you need 12-16 full turns of the lug nut.

If they were steel, 1 times the diameter, so you would only need 8 full turns.

 

So either go back to steel lug nuts or put on the longer studs is the answer?

 

That would be my suggestion. Granted, 1.5 - 2 times the diameter is necessary for maximum grip strength, and less than that may be okay for this load case. But, when I witnessed my friend put on 949 lugs on 6UL's, I didn't like the amount of thread engagement. Maybe someone else has actual track experience to comment.

 

Thousands of track cars are running 949 aluminum lug nuts with 949 6UL wheels on stock studs. ARP studs with more thread engagement would be even more secure, but I would consider the above combo adequate based on the success rate.

-Ryan

 

The general rule for holding any thread is 1.5 times the diameter of the rod, and mil-spec likes if you have two threads poking out of the end of whatever you're fastening.

Pretty sure the 949's wheel studs have more than 1.5 times the threads. And I think that's a good & smart thing.

 

Anyone use Applied Racing Technologies studs?

http://www.appliedracingtechnology.com/products.php