05 Gt Conv. 17' wheels. I am looking to get winter tires for the wisconsin winters, but a new set looks to be around 600+ from tirerack, 1000 from sears or goodyear. plus the $100 for mounting and balancing every fall and spring. Would it make sense to get a small diameter, 16' or 15'? And if so, what size tire would I need? Also, how much weight should I pu over the rear axle? 100, 200 or 300 lbs? Thanks for the help, I'm new around here.
-P

 

I went too Discount Tire. And got 2 Winter Force tires mounted on 16' steel rims for $296.00. They are for my wifes 06 V-6 Pony Pkg Stang. I did try them on the back of my 06 GT, and they fit fine. The rear brakes are the same size on V-6's and the V-8 Gt's 11.8".

 

skinnier the better...
I've driven a stang in Wisconsin Winter for 12 years now.. and All i can say is skinny and schear winter tires for the back are great.

I would say get cheap steel 16" rims just for the rear with 215/65/16. same radius as the factory fronts, so you wont have any traction controll issues.
All four tires means that you need to get 17" snows, but they are expensive, and not as good as narrower 16". (and you can't fit most 16" rims on the front of the gt's, as the brakes will hit the rim. rears are fine for 16" though, as the brakes are smaller.

I've used inexpensive winterforce snows for a while, but this year I'm trying the factory pirelli's.. so Im curious how they will work out...

 

If I was going to run the car all winter I'd put a set of studded snows on CrownVic 16's. Plenty in the junkyard. I would only put them on when weather forecast is looking bad. You'll hear a lot about having same tire on all four. With diameter approx same I personally don't see a problem, especially with limited bad weather use. I know one thing, even with brand new snows you can get stuck on practically level ground; not so with studs. Some states may not allow these however.

 

So I wont' be able to get 16' rims that will fit the GT's front brakes? Studs are not an option here. So from what I understand, I would need to run 16's only in the back w/ a set of tires that will provide the same diameter as the stock17 and all season tires up front.

 

16"s won't fit in the front (17" barely do). OE 17 Pirellis @ 27.3 diameter. As far as not running the same design tire on all fours that's up to you; you'll hear both sides on that one. Oh BTW Chrysler 17"s have same bolt circle, and most will fit, clearance wise. Take measurements of your OE 17"s with you to the junk yard, if you explain what you are doing they will usually let you return the rims no problem if you have a fitment problem. ...but bringing the measurements with you you limit the chance of a fitment issue. (You could bring your car to the yard and test fit one on the front to be sure. Even if they bolt up on the front fine, make sure you have adequate offset/backspacing though so they don't stick out, look bad and kick up snow, salt debris.)