727 in BWI about 1986. Meeting the plane one snowy morning doing a quick walkaround & finishing the daily check, I secured everything & took off completing the first part of my normal split shift. I returned that evening to get things ready for departure in plenty of time, with everything looking good I relaxed even more in the office. With the call for the final fuel load, I strolled out to finish things off & met the FE finishing his walkaround. After exchanging pleasantries, he mentioned they were not going anywhere with a plane in that condition while pointing to one of the main tires where plain as day, right on top is a nice flat spot worn through several cords. So much for my relaxing evening! Snow had stuck to the tires on arrival that morning long enough for my walkaround & then melted away. A friend stopped by to say hello & I promptly got him involved by prepping a tire in the shop while I removed the offender. About the time I got the old one off, he was passing under the plane rolling out the new one. When I turned to get it, he was laying flat on his back on the ramp having squarely connected with the aft drain mast! All I could do was talk to him while chasing the tire to keep it from falling over & continue the job. He managed to shake it off & we got the plane out on time but I have not missed another tire on walkaround! I'm sure he had a lasting impression too!