The 2 factors that will come up most often are the bolt circle size (5x100mm for A4 gen VWs) and what brakes you are running. If you are running stock brakes in the Jetta, then any of the VW wheels will work. Larger brakes will mean that sometimes 15" wheels won't work, and there's some brakes where 16" wheels won't do it either. I'm not worried about larger brakes though, so I can't provide details on that.
After that, the offset will be of interest, but if you are working with OEM wheels, there will be no worries. The variance of offset will run 37 or so to about 45 (the most I've seen). All of these will fit.
If you are running aftermarket wheels, then these same factors will apply. In addition: aftermarket wheels are made to try and fit the largest number of hubs on the market. So you will need to know that the VW hubs have a hub center of 57.1mm, so a centerbore of 57.1mm is required (and yes, I know there's fitment tolerance in there, but the 57.1 is the number you need). If the wheels you want to buy do not have that centerbore, you will need rings to make up the difference. Of course, if the bore is too small they'll need machining, but that is virtually never the problem.
I like the fat fives. Had to sell a set before I moved a couple of months ago. Some guy got a fantastic deal on a set in good shape. Well, they need some refinishing, but he still got a fantastic deal.
Cheers,
PH
