Ok, according to his activity, it seems that he have a 1999 and a Gen 4... So he is at the right place.
As you have 2 SHO, I will probably write things you already know... (sorry). Finding used (I'm searching only used things, it cost less) tires and wheels for Gen 3 SHO may be difficult because the tires have a somewhat unusual size (225/55R16) and the wheels have a bolt pattern of 5 x 108 (mm, -> 4.25 pc) that is also not frequent. Since around 2011, Ford reused this bolt pattern but with a very different offset... (I bought a good set of wheels from a Focus Titanium in 18 inches only to realize that the wheel was touching the strut a lot.) The size of 225/55R16 was used only by one model of BWM from what I know. (Why used tires ? Because good used tires are safer than new cheap (chinese) tires.)
One of the solutions to find more good used sets of tires was to find others sets of wheels in other sizes (16-> 17 / 18 inches) which gave me more possibilities to find differents sizes of tires. (225/55R16 / 235/50R16 -> 225/50R17 / 235/45R17 -> 225/45R18 / 235/40R18) IIRC
The rarity of this bolt pattern was a good thing in a way because people selling these wheels stick with them until you find them, the price is often low. I was able to find a FAST chrome set with 5 arms that look like to the originals ones but in 17 inches. By these times, my trick is to buy used good tires from Subaru WRX owners because their car use Dunlop 235/45R17. (Many people retreive their tires too soon and re-sale them.)
For tires sizes, I will not recommand going above 235 because they will slide in water and the car stick on the road very well with 225 and 235.
Ford took a brake using this setup during some years. Between 1996 and 2011, there are only Taurus and Windstar that using it from what I saw. And sorry for my precedent advice, but here in Canada, we don't see a big bunch of Volvos but maybe there is more in USA...
Interestingly, and for no reason I understand, Volvo does very well out here in the West of Canada. More of their cars than in the east, and way, way more of their full rig trucks. It would not surprise me if half the rigs hauling log and cargo trailers out here are Volvo.
Have a used set of original size Continential DW's on original Gen 3 (97) chrome wheels if interested. Just want to get them out of garage and willing to help another forum member so could be low priced. Not sure where you are located, but i'm in SE WI. Let me know if interested.