by R Keller » Thu Sep 30, 2004 1:33 pm
Stephen:
Just to follow up further...
If you're using a Dexter torsion axle (I can only speak about this brand since I have done no research on the others), you are probably going to be more limited by the need to make sure the torsion arm clears the sidewall and by the minimum hub spindle length, than by the distance of the tire from the sidewall.
For an explanation of what I mean by this, I'll use dimensions from my trailer as an example:
The outside chassis frame width is 57.5" and the sidewalls are 2.5" wider (1.25" each side, to allow for skirts that hide the chassis) at 60". The torsion arms each have 3/4" clearance outside of the sidewalls, and therefore, the inside edges of the torsion arms are 61.5" apart.
The hub face width is 72.25". This was the minimum that could be manufactured, given the torsion arm spacing and a brake mounting plate (you might be able to go slightly narrower without a brake mounting plate). So, there is 5 3/8" from the inside edge of the torsion arm to the hub face on each side (and 6 1/8" from the hub face to the sidewall on each side).
My wheels have zero offset (incidentally, Dexter recommends to only use wheels with a zero offset with their axles to avoid overstressing the bearings). For my 7 5/8"-wide tires (195's), there is therefore about 2 1/4" clearance from each tire to the sidewall.
So, as you can see, the tire clearance was determined by the necessary clearance for the torsion arms and the minimum hub spindle length that Dexter is able to do. I was not able to get a smaller tire clearance.
Hope this helps. Dexter has lots of drawings on their site that help in figuring out these dimensions.
Rik