I got a flat on my X type i was told by someone that i have to change all my tires, but i spoke to my mechanic and he said once the front tires have more than 70% thread life left ill only have to change the pair in the back. Is that true ? also does the thread pattern have to match excatly to the ones in front ? because i am currently running a marangoni zeta linea tire that isnt available in the US anymore.... your expertise help is needed asap, i dont wanna damage my transfer case