SWEDISH BLUE:
I was a tyre fitter when Super Singles came out, mid 70’s I think. It was an enlarged rim with only 1 tyre fitted, as opposed to 2 rims and 2 tyres.Original tyre sizes were 10.00 x 20 crossply with a tube and flap fitted to a 2 or 3 piece rim. Then we got 11 x 22.5 x 20 Tubeless tyres.
I think I got the sizes right but it is a long time ago.
Yep, did my time on the tyres too in the 70’s.
Super singles arrived in the late 70’s if i recall correctly, i was on the road by then, as weights increased to 38 tons (most commonly via a 3 axled trailer) new trailers were almost all on super singles but many converted tandem trailers continued with 12 normal tyres for some years.
You’ve got the sizes spot on, a 10.00 x 20 was indeed the equivalent of an 11 x 22.5 tubeless, a 9.00 x 20 being equivalent of a 10 x 22.5.
Those converted 3 axled trailer still running 12 wheels could have a mixture of tubed and tubeless wheels, don’t recall the different types being fitted to the same axle (radial and cross ply not allowed on same axle) but happy to be put right if that was permissable at the time.
Super singles on trailers have made life much easier for tyre fitters, very seldom do they remove wheels to change super singles, easier for drivers too when checking for punctures.
I remember seeing the odd tractor unit with super singles on the drive axle, haven’t seen one for years.
Just thinking aloud here, if you had a drive axle blowout with super singles on a 4x2 tractor wouldn’t the vehicle be naturally inclined to spin out or go into an oversteer? whereas the still inlfated single tyre keeps it both level and stable enough to bring it to safety, be interested to hear from anyone who knows the ins and outs of this.