I'm also very interested in this topic as I'm doing research for my own build upgrades. I have seen elsewhere it suggested that the link separation at the axle side be a certain percentage of the intended tire diameter in order for them to control the axle effectively. I believe it was close to 25% if I remember right. I'll try and see if I can find the link and post it here. If it's correct a 40" tire should have a link separation of 10" at the axle, but perhaps using bigger joints and stronger mounts and control arms could reduce that amount? If that ratio is accurate then a 35" tire would require 8.75" of separation.
My newest build:
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