2016 2500 hd. 6 ltr gas pullin a 25ft wildcat 5th and have to hit 70 or can't run in top gear-it will down shift to 5th around 68. get 9mpg on level,never heard about tires havein a 65 top speed??Been around the usa and to Alaska,probably 40,000 miles.Wore out 4tires and have had 2 blowouts,Consider that normal since I'm within 100lbs of full load weight.People HATE IT When a 5th is in front of them,will pass me ,JAM ON the brakes and exit or Worse yet Slowdown and make me dog it up a hill in 3rd gear.