Is there any problem changing to 18 inch rims on stock 4wd? I use Hypertech programmer so I can recalibrate the speedometer

 

Nope, You can actually run the same sized tires (overall height) on a 18" rim as what came on it's stock 16"s, that's what came on my 18"s when I bought them. I've now upgraded to 35"s with 4.88 gears, haven't recalibrated the speedo yet but I know the offset based on GPS speed and miles.

 

How many rpms do you turn at 65 with that set up Tom?

 

Don't know what size tire your going with but my Hyperpac will only let me program upto 33.5" anything over and my truck won't start and hyperpac will show an error.

 

I documented this on the way home with the new rubber when I bought the Nitto Duras, they are 305/70R18E specced to be 35.28" tall, rear gears are 4.88.
Speed verified by GPS on a flat level stretch of I-495 in DE and RPMs were taken from the Ultra-Guage's digital display;
50 MPH = 1720 RPM
55 MPH = 1900 RPM
60 MPH = 2055 RPM
65 MPH = 2230 RPM
70 MPH = 2408 RPM
75 MPH = 2580 RPM

 

Wow, you are built for some serious towing

 

For our situation and usage that's all that really matters Michael, Everything that I've done to the Ex has been directed toward making it a better tow rig!
The old 32" tires at 65 MPH had the motor turning at 2430 RPMs, beast mode!