Prius v winter wheel offset

I am looking to get a set of winter tires and wheels for my new to me (this spring) Prius v 2012 5 trim. The tires on it currently are pretty awful, offering such terrible traction in rain (2 instances of all 4 wheels breaking free while cornering at aggressive but not unreasonable speeds (following another car in one instance which had no problem), abs on braking, wheel spin) I am afraid that despite significant winter driving experience they will to dangerous for use even in the DC area's mild winter conditions.
Currently as it is a 5 trim the wheels specs are:
215/50ZR17 tires
7Jx17 ET45 (7 inch wide wheels, 17 inch diameter, with a 45 millimeter offset)
5x114.3 stud pattern
60.1mm bore

I have found a set of 16" steel wheels on craigslist I would like to get that were used on a Lexus IS300. I am a bit concerned however that the offset for these wheels is 50mm when the standard for the 16" Prius wheels is 39mm. Specs for wheels:
205/60R16 winter tires (Continental Extreme WinterContact XL)
5x114.3
16x6.5
+50
67.1mm bore

I don't think this would be enough to cause the tires to be pushed into the wheel well so far that they rub, but I could be wrong. I am concerned that the difference could cause to much load on the wheel bearings or affect handling to a significant negative degree.

TL;DR: Is having 50 mm offset on 16" wheels on the Prius v when the stock 16" wheels have 39mm offset?

Bonus: Can anyone describe how to best handle the Prius when all 4 wheels break loose? It it a bit scary. I am used to a rear wheel drive manual that always let go with the rear way before the front. The Prius seems to understeer (front wheels loose grip first) as typical for a front wheel drive car, but the rear wheels very quickly let go after (I am guessing due to heavy battery at the back). While there is traction/stability control and it does kick in, it seems like there is probably some techniques that can help (i.e. rear wheel drive opposite lock to keep back end from kicking around on you)

 

Yeah I was worried about the bore difference. However this web site on wheel bore makes it seem like the bore is only important for centering the wheel, not for actually supporting the weight. Multiple sites selling plastic bore rings seems to confirm this. The seller also says that the bore was different on his Lexus IS 300 but he just centered using the studs, tightening them alternatively to center the wheel and had no problem.

 

Ahh that website makes things more clear. Compared to the 17" wheels that 16" with the larger offset the wheel will still be 1.3mm farther from the strut than the 17"s so there should not be any clearance issues. 11mm closer to the strut than the stock 16"s. With the wheels closer in it will narrow the stance of the car by 22mm (2.2 cm) I don't think that should have a major impact on stability. So should probably be fine

 

Can't find any available in my area at the moment.