Wondering if anyone has 285s on factory chrome 18s and how much did it change your speedo.

 

I have 285/55/18's on fx4 18x7.5 alloys, mine is a 2010 xl reg cab shortbed. I just bought an Autospring 2.5" level kit and plan on 285/75/18 Nitto's, Toyo's, or BFG's, can't decide on which tire yet. With the 285/55/18's, I have way too much room in the fenderwells, but the tires fit flush with the fender sides. Thought about the 295's, but have heard too many rub/no rub issues, although they look beefy as all get out. Anyway, back to the speedo issue. Most people don't bother to recal their speedo's. I will after the mods. I get 17.8 mpg in the city and 20+ mpg @65mph, bone stock 4.6 2v, auto trans. I bought the truck new and originally came with 17's and doubt the dealership recalibrated the speedo. I'm told the 285's will have minimal effect, maybe 6% ?? But just for the peace of mind, I will do the recal.

 

Thanks

 

You haven't given enough information to get useful responses.... 285 width tire with what aspect ratio? What size was original? There could be someone with 285/55R18 tires, or someone with 285/70R18 tires and they are a huge difference in OD...

To get the change in speedo, you find the percentage difference in tire OD, and then the speedo will be off by that same exact percentage.