Collar ties are generally for the benefit of the rafters though and your rafters sound more than big enough.
Removing roof collar ties.
You might actually need 2x8 rafters in such a case.
The one in the middle is around 3ft height which results in an awkward limbo or high jump.
There is 3 supports on the loft which i believe are either called rafter or collar ties which divide the loft into quarters.
Removal of collar ties steve re.
Collar ties are the appendix of roof framing an evolutionary dead end in home building hanging on by just a couple of nail points.
It ties the entire roof together.
Well unless your roof is concrete tile and less than 3 12 in slope.
2x4 collars yes i use a piece of 2x4 placed immediately under the existing ridge like a collar tie but all the way to the top on each pair of rafters.
Watch this video before.
An exception occurs however even near the ridge if the bottom of the roof triangle is not secured against stretching or flattening by a ceiling joist or a low placed rafter tie.