Ok , this will become our home moving about every two weeks working our way to lands end in South America. Most driving will be dirt sand and rocks. im in no hurry 50/55 is ok with us, we stay off the interstates and toll roads our off road speed is about 30 mph on graded roads. I like the XZLs for the lug size and the ground clearance they provide.
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For that kind of
"riding the roads" I think replacing all six tires will make you a whole lot happier as you go on your adventures. If you have a blowout, you will need: wheel chocks, cribbing material, a 20 ton hydraulic jack, a really good battery powered 3/4 impact wrench (or a one inch), and the appropriate wheel socket, a four foot tire bar (crow bar would work). AND don't forget the all important spare tire.
If you have never changed a tire on one of these trucks I would like to encourage you to change a front and a back. See how you feel afterward.
Then, If it is really hot - or if it is raining like the world is ending - or if your spare went flat and you didn't know it -- You will be a really happy guy when you DON'T have to change a tire on the side of the road. But you need the practice... Before you need it.
Not trying to get you to spend money you shouldn't have to immediately spend. Not trying to scare you off either.
On the other hand, if that
road trip is really your plan - I think
new tires need to be
near the top of your list.