Max width using Extension Brackets?

[bspisak]

These brackets come with an 18" tube. Can I use a longer tube to get a wider support table? Or is there some reason 18" is the max useable?

[dusty]

Eighteen inches allows you to set up with two extension tables being used as either infeed or outfeed tables on the same side of the main table. The main table is 17 1/2" wide.

If you want to span a larger distance (main table plus extension table) you will need to use tubes that span that distance.