How far do those bolts extend into the hub? Are they perhaps a little short? Look like about 6 threads stripped. If pitch is 1.5mm, that is 9mm. Insertion should be about 17mm?

Not suggesting they should be torqued that tight though. But with factory length bolts, especially extended ones like on the W210, they have been known to shear off before they stripped the threads.

This video seems a good guide:

 

Thanks! Good video. The bolts are 95mm total length, have to take the wheel off again to measure how much goes into the hub (subtracting the rotor). I will go back to the tire shop to get them to re-thread the hub if possible.

 

That video is crap. 17mm is too generic for all wheels. It should stick out at least the thickness of the rotor in the hub area and the hub thickness itself and about 1 additional thread. Too far and the bolts hit things on the inside. The thread engagement shown by the OP looks correct its ~ the thickness of the hub.

But don't pay any attention to me. My wheel just fell off last weekend.:big laugh:

 

A regular 12mm hex nut is 10mm thick. Add 1 thread for projection and you get 11.5mm. That would be minimum for bolting. Add to that the rotor thickness for length of bolt that should project. The rule of thumb is 1.5xdiameter, so that is probably where the youtube number came from, and it may very well be too much for rears. Only way is to measure the hubs and disks or do a test with a factory bolt and wheel.

The 5 or 6 thread engagement that OP appeared to have is only 7.5 to 9mm - not enough for a 12mm bolt??

A basic requirement of bolted joints, is that the bolt should shear before the threads strip.

ADDED: I checked the stud length on my 350SL using one stud from a rear wheel and the spare wheel which like the others is steel. The youtube video doesn't say what they mean by bolt length. It is from underside of ball to end of bolt. The one below is 21mm, not 40mm. On the 107 with steel wheels, the length is 21mm. There is an indent in the wheel, so the length protruding from the inner face of the wheel is less - As it happens, it is about 17mm. It was hard to measure the rotor thickness without removing the wheel, but I measured about 5.5-6mm. This would leave about 11-11.5mm of thread for engagement in hub and extra that protrudes. It could very well be that hub has only about 9mm thickness or 6 threads? Maybe someone has one that they could measure.

 

I will measure the factory lugbolts and measure how far they protrude from the hub of the factory hub.
A bunch of German engineers can't be too far off.

BTW- I sold my chrome euromeister 560 rims to a friend with the supplied lugbolts. The shop that mounted them said they had to cut the bolts as they hit the emergency brake.I think the bolts were 40 mm. I am away and have an extra set of supplied bolts.will have to measure when I get home and compare to the factory bolts for the 560.

Anyone have problems with the bolts being to long when putting 560 rims on a 380 sl