JJD's Twin Tyres dually system from the 1980s.
Fullsize image: https://s3-us-west-1.amazonaws.com/h...s_fullsize.jpg
https://s3-us-west-1.amazonaws.com/h...twin_tires.jpg
2:14 video by Because Racecar:
https://www.youtube.com/watch?v=Lql_X_nekCQ
Previously:
https://www.homemadetools.net/forum/...436#post131673
https://www.homemadetools.net/forum/...637#post163003
https://www.homemadetools.net/forum/...891#post175534
https://www.homemadetools.net/forum/...244#post172791
https://www.homemadetools.net/forum/...375#post116676
https://www.homemadetools.net/forum/...710#post163296