How do I perform a reduction cut on the trunk where branches are thin?

[curiousAboutTrees]

I inherited trees from the previous owner, and I am not looking to replace them right now.

Tree: Coastal live oak
Goal: reduction cut to remove tallest 1/4th - 1/3rd branch/trunk.
Issue: Branch thickness is too small compared to trunk thickness. Same issue with a couple of other branches. It is my understanding that when performing a reduction cut, the smaller limb should have at least 1/3rd the thickness of the limb you are going to cut. My concern is if I cut a thick branch/trunk, a smaller limb might not become a leader from the cut area, and instead, shoots will grow from the cut.
How do I handle this?

 

[Jed1124]

What is the diameter of the reduction cut you would like to make?
Pictures with lines drawn where you would like to make the cut would be helpful.
What is the objective of the reduction?

 

[curiousAboutTrees]

1A. I want to remove the main branch; the 4.14 inch diameter.


1B. Has 4 branches. I want to cut the two biggest ones; 3.67inch diameter of the biggest branch, and the 2.7 inch diameter of the second biggest branch.

Uploaded pictures.

Objective: We are not comfortable with the height of the tree. And I want to make changes gradually to remove tall branches.

 

[Jed1124]

Cuts that size are going to introduce decay into the branch union, which will eventually compromise the structural integrity of the tree. You are much better off working out on the ends.
Tree height does not necessarily mean it is a hazard.
Reduction in sail is best accomplished with small cuts on the tips of the branches.
A certified arborist on site would be your best bet in getting a proper evaluation.
I get clients all the time that assume their tree needs a reduction of some sort that is completely unwarranted. Untrained people selling themselves as arborists will often come in and hack off the top of the tree because it’s what the client wants.
Beware of those people.

 

[Jed1124]

Good pictures by the way! I’m not sure of the status of oak wilt or sudden oak death in your area but I would assume it would be best to prune in the dormant season.

 

[jefflovstrom]

Yeah, that is too much at one time. The first pic looks like it will open up for decay. Maybe go higher and select a better option. The 2nd pic, pick one cut , but not both, better to do this over a couple seasons rather than all at once.
Jeff
It was a beautiful day!

 

[jefflovstrom]

Not comfortable with the height? Makes no sense.
Jeff

 

[curiousAboutTrees]

Regarding pruning in the dormant season,
UC Berkeley recommends pruning in late spring or early summer.
Calscape recommends pruning in during July or August.
UC Division of Agriculture & Natural Resources recommends pruning in summer.

This is confusing