i have 255/55-18 falkens ziex z04s on my escape. rims are 8.5x18 Rays G-Games 77S w/ 45mm offset. the correct original tire size and diameter for the tribute/escape in the US and Japan are 235/70-16s or approx 29inches diameter, just like 255/55-18s. Their differential ratios are 2.93 just like ours so I can't figure why Ford Philippines put on 215/70-16s (28" diameter). Maybe to make the speedometer/odometer to read faster para perceived better mileage?!?
Toyo and bridgestone have similar sized tires. Once you have your new tires&rims fitted you'll have to lower your ride as it'll look really weird w/ low profile tires and lifted look.
Expect to have a stiffer ride even without the lowering springs.
BTW, i had 7.5x18s before w/ the 255/55-18s but they looked too narrow for the tires. w/ the 8.5x18s, the tires' sidewalls are flush w/ the rim whereas before they were bulging slightly out.
If budget permits, try 19" rims! Parang bitin itong 18s.