37/64” drill 14 mm is too small. You need a bit of clearance.
I have 5 mm spacers on mine to clear LT215/75R15 tires from the upper control arms. E320 15” wheels.
I put studs on the front for convenience. (You’ll want to do this. Trust me.)
You’ll need small ball seat lug nuts/bolts.
My stud length in the rear is 55 mm.
Ebay has raised hubcaps that will complete the appearance upgrade.
<https://www.ebay.com/itm/363232379347>

Christopher at T3technique.com is your friend.
He has all the ‘right’ answers.

Jim

> On Jan 13, 2021, at 10:15 AM, David M <covrambles@YAHOO.COM> wrote:
> 
> I finally managed to find a set of Mercedes alloy wheels off of a 2005 C240.
> These are the 7-spoke 16x7 wheels with ET31.
> The Mercedes part number is 2034012802.
> I know I need to drill out the lug holes from 12mm to 14mm.
> What else will I need? Will I need new studs or spacers?
> I'm thinking I'll fit 205/65-16 XL tires to the new wheels.
> My van currently has the 14" factory alloys.
> 
> -David (1987 Wolfsburg)