I know there have been many questions asked about wheel spacers and by reading through all the old posts it appears that people have used 5/16 spacers on stock lugs. I bought some 7/32" spacers which were the smallest I could find and I want to use them with my 99' corvette wheels but I am concerned because there are 2 threads from the lug nut that aren't in contact with the wheel stud. Is this ok or do you guys think I should get longer studs?

There are about 4.5 good threads from the lug nut contacting the stud. I have read that many people run 1/4" spacers and mine are a tad thinner but I still don't want to risk a broken stud and have my wheel fall off. I love the look of the wheels with the spacers but I want to be sure to be safe. My other option is to find some 1/8" spacers or buy some aluminum sheets and make them myself.

Please let me know if anyone has personally experiences with a 1/4" or thinner wheel spacer on stock studs.

Thanks,
John

 

NHRA requires that the threads engage "one diameter of the stud, within the hex portion of the lug nut". That means that you have to have at least 12mm (~1/2") of thread engagement between the stud and the lug. That means the stud does not have to reach the end of the lug, IF the lugs are long. I've seen other recommendations that the engagement be 1.5 diameters, but I haven't seen too many stock lugs that have 3/4".

Spacers increase the bending loads on the studs. The thicker the spacer, the more bending stress. You already have shear and tension stresses, and adding the bending stess reduces the margin of safety in the stud's design. I have 5/16" spacers in the front for track use, but the front studs are only carrying the weight of the front of the car, unlike the rear wheels that have to carry the weight of the rear of the car, plus transmit up to 5,000 lb-ft of torque off the line.

 

Thanks Injuneer. I am going to try the 7/32" spacers only on the rear. I think that do to the front rotors being thicker that there is less space on the front studs for spacers than the rear. As you explained before (previous posts and the FAQ thread), the front corvette rims have the proper backspacing, it's just the rears that need to be moved out a little bit.

Thanks for you advice and help. During my next autocross racing session I'll find out if the studs bend or if the lugs move at all.