I have a set of Audi OEM 16" alloys from a 2002 A4 - - been trying to
get a straight answer on if these will fit on a 2008 A3 (USA
Specifications).

The A3 came with 17" wheels in the USA; apparently, 16's are the stock
wheel in other countries (eg, UK), but its unclear if there's any
corresponding change in brake rotors that would cause any problems.

In asking around, it seems that the responses I'm getting are really
trying to dodge providing any answer because NHTSA mandated a Tire
Pressure Monitoring System (TPMS) for the US Market, which isn't
currently present in these older wheels/rims.

I suspect that the rims may very well mechanically fit just fine, but
because they currently don't have a TPMS currently installed, they
"shoudn't" be used (due to NHTSA), and a shop doesn't want the
potential liability of fitting them.

What's not been suggested by anyone is to simply buy a TPMS and
install it, even though this would require having the existing rubber
taken off, put back on & rebalanced.

But it still comes down to the first question, of if 16" rims will fit
or not.
Any suggestions before I break down and jack the car up & pull a front
wheel?

-hh