With the miles I put on it comes down to when a tire is replaced the pads get done. Seems to work out about right , and never end up having to do an unexpected pad change while on a ride somewhere.

 

You have all you need to know, in the mileage you have done to date and the remaining thickness of your pads. That removes the need for us to tell you that it depends on how you ride, as we all know that now! Do be wary however, as like tyres, as your pads get closer to the minimum thickness they are likely to wear more quickly, as they heat up faster due to the thinner remaining material. Don't assume you will get 20k more miles out of them, but do check them at intervals.

 

Once your pad material gets down to "30%" then it's time, especially if you are doing tire work. That's the prime opportunity.

 

Page 174 table 56 and 36 ( 2017 )
Minimum Brake pad friction Material Thickness IN 0.016 MM 0.4

 

I think I am good, as stated in my first post, my front used pads have 0.102" left, and new brake material is 0.137" brake material.
My trip will have a lot of freeway miles.

 

From the figures you gave us earlier it looks as if you are light on your brakes, so probably have plenty of miles yet. Do check your tyres though, so you have plenty of tread before you set off!

 

I already did. My front tire might have made it, but might not also, so I had a new one put on a couple of weeks ago. The rear tire is almost new so it is good to go.

I have not checked my rear brake pads yet, but will do that soon. I hope to report on them soon.