Making custom grillz for the whole Astros roster wasn't good enough for Paul Wall ... 'cause he just commemorated the team's first World Series with a HUGE back tattoo!!
Wall rolled through G6 Tattoo Studios in Houston for the fresh ink -- which he showed off on Wednesday with his "World Series Grillz" track bumpin' in the background.
The H-Town MC's got several tats reppin' his civic pride -- but this one's probably the most epic.
Speaking of those grillz ... the 'Stros came through Wall and Johnny Dang's shop recently to get 'em molded -- and word is they're ready for pickup!