Re: 49mm offset with 225-60-R16's on a Jetta 4. Will it work? (The Bastard)
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.
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.