There can be problems with having different brands and types of tires. The main one being different tread patterns will cause different wear and will drive differently in rainy conditions causing possible accidents. They will also not wear evenly and will wear out in advance of their years.You also list 2 different ratings of tires. ( S and T ) These ratings tell you the hardness and durability of each tire. I would stick with the same rating of tire on all unless you are in a sports car and a Z rating with cost you twice as much and last 1/2 as long.A good general wear tire either S or T rated will run you between 40 and 70 dollars each depending on the brand. Both of those brands are good as well as Michelins which will be a bit more expensive. I tend to not to scrimp when I purchase tires and brakes because they are the most important thing to have work well.For a minivan I would go with something that will last between 60k and 80 k miles for the warranty. This I think is a S rated tired and is considered a bit more "hard" of a rubber.Good luck!