Re: 49mm offset with 225-60-R16's on a Jetta 4. Will it work? (The Bastard)
Tires:
The correct overall tire diameter needs to be 25", give or take a tenth or two. 225/50-16 tires are the same 24.9"-25" diameter as the 205/55-16s that VW puts on stock. Your 225/60 would be too tall, causing speedo error, slower acceleration, and butt-ugly looks. It might even rub the inner fender when the steering wheel is locked all the way to either side.
Offset:
The correct offset is 35mm to 42mm (stock 16x6.5" OEM wheels are ET42). A 49mm offset would set the wheels too far into the fenders. You could use H&R Trak+ spacers - 8mm would work - and the wheels might be OK. Check the brake/wheel interface for clearance, tho.
One thing you didn't mention is wheel center bore. VW uses a 57.1mm bore, so check the wheels. Too small and they won't go on at all. Too big and they could cause vibration.