I also still had the tires that came with the truck. I'm still using the plugs that I had in my old block--the one that was burning a quart of oil every 40 miles. I cleaned them up as best I could, but maybe I should just replace them.
Check the date code on the tires. Old rubber isn't safe on the roads, especially on long hauls where you will be heating them up more and for longer periods than short runs around town.
Spend the money on a new set of plugs.
just my 2 cents.........
