On a 5 lug conversion, are the rear studs longer than the fronts? Options

[turnaround89]

Is the most common length for a wheel stud for fuchs rims 45mm? Are the rear lugs supposed to be longer at 52mm, or are they also 45mm?

Also, why are wheel studs 7 dollars a stud? Have to buy 20 studs, 140 for studs is a little crazy

[underthetire]

You would have more leverage on the stud the further out you go with spacers. I would think anything under 1/2 inch wouldn't produce much more side load. I have not run the numbers yet to determine dynamic stress differences. The same question was brought up with grade 5 studs vs. grade 8 studs. We found if the nuts were torqued to grade 8 specs and kept there, they were stronger. If the nuts came loose, grade 8 didn't allow for flexure as well as the grade 5 did without braking.

SO....keep your nuts tight !! (IMG:style_emoticons/default/happy11.gif)

[Richard Casto]

You would have more leverage on the stud the further out you go with spacers. I would think anything under 1/2 inch wouldn't produce much more side load. I have not run the numbers yet to determine dynamic stress differences.

Actually I am not sure I understand the physics of that statement. I think it's the change (if any) of the location of the contact patch with respect to the hub that maters more than anything.

I think you generally have two forces on the studs. Shear (i.e. the wheel trying to rotate against the hub) and tension (the wheel trying to pull away from the hub). The loads are created via the tire contact patch. Take the example of two different wheels with the same width, but different offsets. By using a spacer on one wheel to create an equal offset for both wheels (both will have the same track) the loads when measured at the hub (tension and shear) should be the same between the two wheels regardless of stud length.

Now if you are moving your contact patch out and creating a wider track then the loads on the studs at the hub should increase. But I don’t see the load on the stud at the hub being any different with bolt on spacers vs. spacers that use longer studs. My fear about bolt on spacers is that they hide something that can come loose. I think it would be easier to check torque on long studs than having to deal with removing wheels to periodically check the torque on the bolted on spacer.

What I am curious about is issues such as hub centric spacers vs. lug centric spacers and the differences with respect to shear loads on studs. Particularly on wide spacers. In general bolts (in this case wheel studs) should not be used as a centering device. But there is the reality of the lug centric design that uses studs to center wheels. I don’t know if they exist, but I would think the most flexible solution would be hub centric spacers that work with long studs.