Are you going to track the car often? (Road course)
If no. And you’re only planning on having one or two sets of wheels with similar offsets (nothing larger than say 15mm difference in ET, something you could toss a slip on spacer for). Stick with bolts, no need to waste money on studs. They come OEM on pretty much all BMW/Porsche/Audi/VW and some other random brands I’m forgetting. The wheel is hubcentric anyway, taking it off and putting it back on is not a pain, just set it on the hubcentric ring.
I have a bmw that makes close to 1000hp and i DO run wrinkle walls and i DO use the standard bolt from bmw. So im not sure why stregnth is of any concern here. The only benefit i can see coming from studs is possibly buying a better grade material, and for use with aftermarket wheels that might not be able to use the standard bolts.
I think the main point here is that there are a variety of other things to be concerned with before you start breaking wheel studs/bolts. Either one will work just as well as the other and it seems to be a matter of preference.
A stud is a bolt the only difference is the head. One is pressed in and the other is threaded in. If both are of the same material and same dia then they should have equal strength.
---------- Post added at 09:10 AM ---------- Previous post was at 09:04 AM ----------
false. it’s not about the shank itself, but the engagement to the hub.
and don’t compare studs that are pressed in from behind the hub to the screw-in studs that travisin posted. The BIGGEST difference is the “shoulder” area. If you have stud threads at the hub face, you are much more likely to snap a stud then a pressed in stud where the threads stop short of the hub face.
In tension, a threaded stud and bolt relies on the shear strength of the threads, while a pressed fit relies on the shear strength of the flanged head.
In tension, a threaded stud and bolt relies on the shear strength of the threads, while a pressed fit relies on the shear strength of the flanged head.
What about the nut that is threaded onto the stud. Does that not also rely on the strength of the threads?
Im just trying to understand why one is stronger than the other.
Hub strength: A stud conversion is different than a factory stud.
A factory stud is pressed in from the rear, In this case, the material on the hub’s main mode of failure is only in compression. When you thread a wheel bolt in, the threads in the hub are in compression AND shear. Unless you’re running some super baller hub, the bolt material is always going to be WAY stronger than the hub. In this scenario, wheel bolts and thread-in studs provide the same strength. Only press-in studs have an advantage here (without doing a calculation, I think it’s a BIG one)
Fastener strength:
Given the same material, a stud is stronger than a bolt. The weakest point of a bolt is the radius under the head. You can lessen this problem by placing an undercut under the head of the bolt, but you also decrease the bolt’s effective cross sectional area. A threaded stud has no undercut and no radius, and in theory is stronger. A press in stud still requires a radius for maximum strength, but the head effect is lessened by the friction of the interference fit.
I have never heard of any kind of studs or bolts failing when properly torqued. I would say the factory setup is probably 5 times stronger than it needs to be. So really unless you are just curious there is no need to answer the question.
I will say this; 5 studs/bolts are probably at least 25% stronger than 4.
that’s the only equation that would even come CLOSE to having a wheel part ways due to shearing, considering the shear strength of 12-14mm hardened bolts is pretty high, and if you’re kosher, then… they’re plenty strong.
---------- Post added at 11:18 AM ---------- Previous post was at 11:15 AM ----------
thread in stud kits suck… i know some people don’t have problems, but I am NOT a fan.
The only logical reason to have bolts in the first place is a lower cost of manufacturing. Studs are easier to work with that is my preference but I could not ever see myself converting from one design to the other.
lug bolt
drill and tap hub
manufacture bolt
insert bolt into hub
stud and nut.
drill hole
manufacture stud
press stud into hub
manufacture nut
insert nut on stud
We were having this discussion today (Basically why do European’s use wheel bolts when everyone else uses studs) and I wondered if it had ever been asked here. A couple things we came up with that weren’t in this thread.
Less likely to back out since the wheel bolt has more threads in contact with the hub.
With a wheel bolt the threads are more protected from corrosion since they’re buried in the hub. Only evidence I have to support this is working on a friend’s 2003 Volvo and the wheel bolt threads always look nice and clean.
i have had wheel bolts seize into the hub from rust on the back side of the hub on some really neglected cars i had the pleasure of working on at my former place of employment. needless to say, the head of the bolt snapped off like it was nothing.
