Why does Ford always put difficult tire sizes on their vehicles. I had a hard time trying to find used winter tires for my 99 Explorer, and now for the 2002 Sport Trac?
If your local tire shops can't meet your needs, consider buying from Tire Rack and having them shipped in. Tire Rack has an installer network as well - you can ship tires to your installer shop then take car there when they arrive. I've used this in past (here in States) and it works. See Tire Rack's website for Canada coverage.
235/70 or 75 /15 on the 99, and 235/70/16 or 255/70/16 for the ST were very common tire sizes at the time the trucks were new. 15" tires are getting a little harder to find now, but still not bad. I've not experienced any problem finding those sizes.
The 205/70/14 (or is it 215?) used on Aerostars and some Rangers were always an odd tire to find.
I agree with this odd sizes issue. The new 17" on the escape are 225/65-17. When you find them. The most stores' only have 1 brand to choose from. The prices are outragous for them. I can buy 18" tires in choices for less $$$$.