Automakers are constantly tweaking even the smallest features, leading to industry innovations from rain-sensing wipers to six-level autonomous driving. Some changes can go unnoticed until you have a specific type of roadside emergency, though. Car manufacturers didn't all switch from wheel studs with lug nuts to lug bolts at the same time, and both mechanisms are still common. Most new vehicles these days leave the factory with wheel studs and lug nuts, including some two-piece lug nuts that can swell and break in cold weather.
Lug nuts thread onto a set of studs which are mounted to the wheel hubs at the end of each axle. Those studs extend through holes in the brake disc or drum and past the recesses in each wheel to be capped off with lug nuts. Mounting a tire with wheel studs allows you to hang the wheel on the studs for proper alignment, which you can't do with wheel bolts. German manufacturers have embraced wheel bolts more enthusiastically than their Japanese and American counterparts, mostly to make production a little simpler and cheaper. There are reasons for and against each format, so read on to determine how important each one is to you.
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Instead of requiring a threaded mounting point in the hub plus a stud and a lug nut, lug bolts only need a mounting point and a lug bolt. Cutting even a small part out of the manufacturing and assembly process can lead to significant savings, especially when that part is used 16 or 20 times each on millions of cars a year. Fans of cars from BMW, Mercedes, Porsche, and Volkswagen know that these German automakers are champions of the lug bolt, even though these companies own several expensive luxury brands.
Owners can also buy longer wheel bolts to safely fit wheel spacers or aftermarket wheels, and it's far easier to replace a worn or damaged lug bolt than a stripped or broken wheel stud. Neither bolts or stud-and-nut pairs are terribly expensive on their own, but removing a damaged wheel stud can be a frustrating, tedious process.
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The big disadvantage with lug bolts it's that it's more difficult to align the replacement wheel for mounting. Many hubs and wheels have matching machined grooves to make it easier to match up their centers, although you'll need to hold the wheel in place and turn it slowly to line up the bolt holes in the wheel with the threaded ones in the hub. Many wheels have alignment dowels to help with this, but it's also possible for the brake disc to rotate out of alignment.
It can be especially tricky to hang aftermarket wheels with wheel bolts; some universal-fit wheels have an oversize bore that may not fit snugly on the hubs of your specific vehicle. There's another advantage in that bolts don't stretch as much under load as stud-and-nut combinations do, wheel bolts can be torqued more precisely just like cylinder head and valve cover bolts. Juggling with a wheel while screwing in lug bolts can also lead to cross-threading of the holes in the hub, so some builds like Jalopnik's Project 996 Porsche have been converted from the original bolts to American-style wheel studs.
