I would recommend that you check your speedo before with a gps and you will find that it is actually faster than what you are going with 245's. Mine was an 8% differential after computing on my gps. Cruise control set @ 1900 rpm's = 64 mph with 285/75/16's it changed to 69.12 mph. which is great truck is under2krpm's and I get great milage varries between 18.5 and 20.5.
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