>>1207515not that guy but his welding teacher probably means split tire rims aka widow makers
instead of a rim the rim consists of two parts that can be split so the tire can be put on the rim without a machine
problem is when the locking rim fails and the rim splits while pressurized with the tire it basicly lounches the two heavy metall parts with lots of force in both directions
https://www.youtube.com/watch?v=s2exMOT0-9M