Subaru is a bit of an odd duck when it comes to it's wheel studs, running M12x1.25 bolts. It's not the M12 it's the 1.25 thread pitch that's weird. Now if you're the type of person that takes the wheels off a car only twice a year that fine thread pitch may never be a problem. But if you track, autocross, own multiple sets of wheel/tires for the same car, or wrench on your car alot, you'll remove and reinstall lug nuts dozens of times a year. And when you run fine pitch threads, the risk of cross threading increases. The finer the thread the easier it is to cross thread.
"I'll be careful". Sure. We all say that. But then there's that one time when you arrive late to an event and you need go all "F1-pitstop" and swap to your race rubber. Or you're doing some light wrenching and your brother-in-law want to help, so he pops the lug in the impact wrench socket, turns the psi up to 135, and goes all NASCAR on your ****. Effectively welding the lug to the stud.
What do to?
There's the ARP 100-7716 studs with their bull nose. It's a direct swap out. The bull nose helps to align the lug before trying to engage the threads. You'll need to get a set of open ended M12x1.25 lugs.
Personally I like, and run, Muteki's SR48 lugs on my Daily. They're steel. Aluminum lugs are bad ju-ju and titanium is expensive.
But it's still running a 1.25 thread pitch. Would it be possible to find a set of studs we could run in M12x1.5 or even M12x1.75 instead?
ARP makes the 100-7717. Designed for the Mitsubishi Lancer Evo VIII it's produced in M12x1.50.
But the real trick is can you get it installed in Subaru hubs without welding, drilling, or visiting a machine shop? That is, are the knurl diameters and width the same? According to ARP they are:
Knurl Diameter (in.) 0.565 inAnd M12x1.5 lugs are more numerous than 1.25 so you'd have more selection and cost less.
Knurl Length (in) 0.270 in
Confirmed:
ARP 100-7717 Mitsubishi M12x1.5 studs easily press into Subaru Hubs. Perfect fit.
Unconfirmed but 98% certain:
ARP 100-7718 Toyota M12x1.5 studs. Knurl length's a little longer than Subaru's at 8.3 mm vs. 6.9 mm. Subaru's hub flange is 10 mm thick, so it should be fine. Plus the 100-7718 are shorter than the 100-7717 studs. Weight savings? Aesthetics?