The Touring & Elite have the wider tires, which are more expensive than the Sport & EX-L tires.
Depending on your best remaining tire's tread depth, you might get away with buying only 1 new tire.
The PP computer keeps track of tire speed to control the vtm4 awd system and mismatched tire height can cause problems.
You can measure the tread depth of the remaining 3 tires and put the best one on the rear (opposite your new one)if the old isn't too worn. I don't remember if the tread difference can be 3/32 or 4/32, before awd issues.
Another option would be to measure how tall your tallest remaining tire is and use TireRack dot com's "spec" section, for 20" tires, and find one that is close in height.
My Contential cross contact 265/45/20 tires were 29.4" tall when new. If after 5000 miles they wear down to 29.2" tall, I could get 1 new 255/45/20 tire, by Bridgestone called "Dueler" that is 29.1" tall.
Finally, you can buy 2 new tires and replace them in pairs, but that's not what you want to hear.