gearing/speedometer differences 2500 to 3500 tire size

[SmokedChops]

Looking to upsize my tires from the 245/70-17 (standard on 1500, 2500)  to the 245/75-17 (standard on 3500) anyone know of VSS changes (i.e. software changes) to accommodate the slightly taller tire?  The van came with a pair of brand new unmounted Transforce 245/75-17, I like the profile, just want to see if anyone here has experience with putting a taller tire on, and how the speedometer reacted.  Thanking. You.

[ASD Dad]

There isnt enough of a difference to worry about.  You're talking a 1" difference in tire diameter.

 

At 30 MPH the difference is 1 MPH, 60 would be 2, etc.  Even going 80 mph with the original 70 aspect ratio tire only equates to 82.6 mph with the 75 aspect.  Over an entire mile you'll get 22 less total revolutions with the bigger tires.

 

I would wager there is more built in +/- tolerance to the system than the difference you'll see in real life.  Speedometers are almost always slow to begin with, you can check with a GPS.  If anything this may make things more accurate!  

[SmokedChops]

calculators I plugged sizes into showed 3.01% increase over indicated.  Was planning on consulting the GPS oracle to check. (I should probably do that beforehand to set a reference)

 

The company I work for builds some of the pin weldments for Blue Ox! Nice to see it in the real world (away from the welding robot)

[ASD Dad]

A 3% increase equates to the speeds I showed - 60mph would now be 62.  Most speedometers are not that accurate (3%) so in actual daily usage it will most likely be a wash.  

 

We Love our Blue Ox!  I have had several WD hitches over the years and this one is by far the easiest, cleanest and quietest to use.  It also just works without fussing with things too much.  I would definitely buy another one and recommend them all the time when we are camping.