Former college football star Justin Blackmon couldn’t fit in the back of a cop car during his public intoxication arrest … with a police report obtained by TMZ Sports stating a larger vehicle was required to transport him to jail.

The 35-year-old ex-Oklahoma State Cowboys receiver’s most recent run-in with the law made rounds on social media over the weekend … with sports fans noting the drastic change in Blackmon’s appearance in his mug shot.

According to the incident report, OSU cops responded to a call regarding a “larger black male” laying on the ground at 1:32 AM on Saturday morning.

According to the report, he repeatedly stated he was going to “Stillwater” … but when told that was a town and not an address, he replied by admitting he did not live in that area and said, “You got me.”

Cops claim Blackmon then turned around and placed his hands behind his back … and was informed he was under arrest for public intoxication.

Cops noted two sets of handcuffs were used “due to his body size and the girth of his wrists” … and when he was escorted to a patrol unit, he was “unable” to fit in the back seat “due to his body size,” according to the report.

Eventually, another unit responded to the location … and Blackmon was placed in a larger patrol car and taken to jail for booking and processing.

Blackmon is listed as 6’2″, 230 in the police report … which is about 20 lbs heavier than he weighed during his time on the gridiron.

After a stellar career at OSU, Blackmon was the fifth overall pick to the Jacksonville Jaguars in the 2012 NFL Draft.