tires/rims dont know how to tell?????

What it the smallest rim size you can put some mickey tompson street tires on for the back i want 15x8(or 15x9 if i can) inch welds for the back and either want to run nitto's or mt/streets without rubbin or modifications i am new to the tire reading world so i dont know how to tell what size tire will fit on what size rim can some one help?

THANKS GUYS!!!!!!!!!!!!!!