Need to know if i can save money using my old tires?

hi got a 2001 honda foreman es i have 25x8x12 on the front 25x10x12 on the back i just purchased 4 ipt rims that are 8 inches wide my question is can i use muy existing tires i have and also my fronts stick out a little farther then the back one guy said i need to buy the same size tires to bring the rear out is this true