I had an incident where I forgot to tighten my lug nuts and several flew off in a short test drive.  I was down to two on one wheel.  I think I've been overtightening ever since.  I have a torque wrench but grew up doing lug nuts by feel.  I need to break out the torque wrench for the aluminum wheels.  I would just give them a light brushing when the nuts got hard to insert.  I was having brake problems so they were on and off frequently.

I just bought a truck though and the spec is 150 foot-lbs for steel wheels.  That would crush the mags.  Pretty sure the aluminum spec is much lower.

When digging through my garage for things to use as a sanding block on these wheels I found a pry bar that almost fits into the wheel hole and measures 17.42mm diameter. I measured the holes again on two wheels and got a range from 16.2 to 17.23, so I bought some domed mag nuts that have a .68” shank, which is 17.272mm, and I’ll open up the holes with a round file and cylinder hone bit until they fit.

I’m just concerned about throwing of the PCD or otherwise compromising the geometry of the holes..

 

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Now I just have to figure out how to turn the angled valve stem Costco installed sideways without taking it back, breaking it, etc.

It never ends.

 

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Incidentally, I went with Michelin Defender T+H - 195/70R14 91H tires. Costco had them for $85 each after the promotion they’re running.

 

3 hours ago, Matthew Abate said:

Now I just have to figure out how to turn the angled valve stem Costco installed sideways without taking it back, breaking it, etc.

Let the air out of the tires.

20 hours ago, Mark Maras said:

 The Cap'n scores again. I checked for a bur on mine, not feeling one I measured 5/8" on the face side. Well just to make sure I just measured the backside. Sure enough, 13/16". No wonder the lugnuts got more difficult to install after twenty years. 

That's 3/16 ths!

Ooops. I said 1/16 above!  Yup, that's a lot of extruded material.

I wish I had written my results down somewhere. All I remember is that the sizes didn't make sense until I figured out what was going on.

 Major Correction. Along with poor light, and old eyes, we can add an old brain. The inside measurement is 11/16". The difference is 1/16". Although  I couldn't feel a ridge there must be about 1/32" of smush in the holes on the face side.

@Matthew Abate Hopping in the Way Back Machine back to the 70's, I seem to remember that Ansen Sprint wheels and US Indy wheels both used the same style 11/16" (hole size) lug nuts. Try searching those brands to see if they're the same size as your Shelby's. I just tried a Google search using "Ansen Sprint, US Wheel lug nuts". SCORE.  Ebay. You'll see the type of lug nuts that I believe Shelby's use.

Edited January 12, 20196 yr by Mark Maras

I had the same wheels years ago and bought some "mag-style" lug nuts from O'Reilly (Kragen at the time). They fit perfectly.

Yep, Bruce nailed it. The .68” mag lugs I bought slip in perfectly from the other side, so it looks like a mix of compressed material in the front and poor measuring on my part. Most of them have zero resistance at all, so I’ll just file around the edges until it’s uniform.

 

These are the lug nuts I got (washer not shown):

 

Cool. I know you know this, but just be careful with the file. Fine tooth file and do a little bit at a time and don't remove any more material than necessary. Remember that they are lugcentric wheels and the registration position of the wheel on the car depends on the accuracy of the lug holes.

Don't go crazy with some aggressive rat tile file down in those lug holes and potentially change the center position of any of the holes.

I've heard anecdotal stories about machinists "from the Old Country" that spend their first two years of apprenticeship doing nothing but filing. Then once they mastered how to use a hand file, they were allowed to use some of the other tools in the shop. While I can't attest to the accuracy of those stories, I do know that as simple as it sounds, it's just as easy to screw things up with a file as it is to fix them. I've done it!    

Oh trust me, I'll be taking off the minimum. I will be surprised if it's more than just the very top of the hole since the backs of the wheels were all fine.