As with the rest of this glitchy piece of shit dlc there's no reason for them to explode ifyou dont bump them into each other. I'm sure the hit detection is probably off or something. I'm glad it helped you once you got it to work though. :-)
For anyone else that tries this method, it helps if you crouch while you're releasing a tank and make sure the tank is upright not at an angle so it won't fall over and bump another one.
HALO:MCC >>>>>>> Interested in Online Customs, Squadmates for Ranked, and Co-Op Campaign. I am on 6am-4pm GMT on my nights off (Midnight-10am US Central). Copy this signature with your play times so we can populate our friends lists with fellow Halo:MCC players BEFORE launch!! If you add me do it on XB1 please; my 360 friends list is nearly full.