It has FINALLY been decided...until one of you tell me a better idea haha
KMC685 District in 20x8.5 35mm offset, and 20x10.5 45mm offset.
Nitto 555 G2 all around. 315/35/20 (cheaper than the 305, makes sense right?) 28.66 tall.
Front 255/45/20 I wish they made a 40 because it's 29.06 tall but oh well.
No, putting a 315/35/20 on a little 10.5" wide wheel is not the right way to go....it is laughably too wide for the 8.5" front wheel. For that matter I don't understand the staggered fitment or the use of 20" wheels, either.
What do you do with the car? If it is just "drive around" and you want a blingy, low cost set of wheels and random tires, then just get the cheap stuff. Or do you go to the drag strip, do road course events, autocross? That would help me give better suggestions.... I will assume the latter.
What was posted initially first was definitely a Forgestar F14. This is a flow formed/rotary forged wheel that comes in a LOT of sizes and can be CUSTOM MADE TO ORDER in a wide range of offsets, colors, etc. A bespoke wheel at a very reasonable price.
We started ordering these in 2012 with our first set being this 18x11" front and 18x12" rear using a 315/35/18 Kumho R-compound track tire, above. Since then we have sold hundreds of sets for S197 and S550 Mustangs, using offsets we have tweaked and perfected for each chassis. We also do 18x10 and 19x10" wheels for folks not ready to go "all in" just yet. We make the 11" wide fronts and rears with significantly different offsets - so that the wheel/tire does not "poke" past the fenders or rub on the inside, but they also do not rotate front to back.
Forgestar makes other styles also, and the "CF5" shown above is another popular one. This car is on 19x11" wheels front and rear, also with differing offsets. This is our
most popular size for S197 and S550 cars over the last 2-3 years, as the selection of WIDE 18" diameter tires has gone way down. There are dozens of tire choices in 305/30/19, from cheap to fast to "oh wow".
Again, we mostly sell wheels to "track guys" that understand the importance of running the widest tire, on the right width wheel to support it. If that's not you, no worries...
But some "non-track" Mustang owners have seen the light and still purchase our 11" wide Forgestar wheel package, just to be able to run THE MOST tire. It looks good, fills out the fenders, and gives you the most grip possible - for stopping, turning, or accelerating.
The TSW someone mentioned is just a cheap, shelf stock wheel that is pretty heavy, and not able to be ordered in custom widths/offsets. Again, it comes usually in one size and is available for "some cars", but it is nothing special. Cheap, heavy, and limited options.
We took the TSWs off the C5 above and made this 18x11/ 315/30/18 set for it, which was used in Optima competition (its on 18x12" front and 18x13" rear Forgestars with flares now). We make several "wide wheel" packages for a number of cars other than the S197 or S550 as well, and we make them with custom ordered Forgestar wheels.
There's a $200/off sale going on until Sept 16th on any set of their 18" or larger diameter custom ordered wheels, too. Any dealer can give you that price, just not all of them know the right offsets that fit...
Good luck,