Pittsburgh Steelers head coach Mike Tomlin loves him some Le'Veon Bell -- but he ain't listening to the RB's rap music. 

Bell -- aka "Juice" -- has kinda blown up in the rap world over the past year ... getting some real traction from his Skip Bayless diss track and the secret song he recorded with Snoop Dogg.

But Tomlin tells TMZ Sports he hasn't listened to a single second -- not because he's anti-Juice ... "I'm too old for all that."

Tomlin says his teenage kids are probably Juice fans -- but he's an old school kind of a guy. 

"I'm 45-years-old man. I like Erick and Parrish Makin’ Dollas -- I’m an EPMD guy."

BTW, Tomlin was out with his pal, Jay Glazer -- and the two of 'em weighed in on Mayweather vs. McGregor ... with the Steelers coach basically putting the super fight on blast.

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