We ride alot of off road here in WV
This is what I carry YMMV
Fender Bag= 1 21" tube
Tank bag includes
1 17" tube--Not necessary,you can use a 21" in a pinch
3 Motion pro spoons
1 slime air comp
1 roll of a good quality electrical tape
One little valve stem removal tool
Tube repair kit (bicycle)
Tool bag has
small cresent wrench
8,10,12,14, 1/4 in drive sockets w/6" extention
6,8 mm allen sockets
Leatherman tool (priceless)
Air pressure guage
extra spark plug
There is also a bunch of misc crap rollin around in there.
The electrical tape is in there incase you eat your rim rubber.This happened to me a few weeks ago in the pouring rain on a rocky,rocky rocky trail.It was also on a pretty good downhill so there was no stopping untill the bottom.i knew the front had gone flat but had to wait till the bottom of the hill.When I stopped and looked down,the rim rubber was wrapped around the speedo hub
Not having any electrical tape between the two of us,we slit the other tube and put the new tube inside for the rim rubber.The old tube was unrepairable 'cause I was runnin around 10/12 lbs.and sheared the valve stem LOL.I read a ride report once where a guy was in S A and ruined his tire and tubes and got by with stuffing some clothes into his tire.
I wouldn't want to go that extreme tho'