Actually - I STARTED with 32's on my X, and 3.73's....All I had to do was check off two boxes more, and bingo.

I just wish the 4.10 option was still there...they dropped it after the '07's

 

...and this just shows how much I need a refresher course in mathematics, haha.

Good info. If I upgraded to bigger tires I definitely would forget about the adjustments in MPG, distance traveled and the actual speed i'm travelling.

I may have to stick to stock for awhile

 

you must have upgraded the tires then. the X base model comes with 225/75/16 tires.

 

That's correct sir. I also added dual tops, and other options.

S Package IIRC gave me the 255/75/17's, and some other stuff.

I clicked the $50 box to get 3.73's instead of 3.21 diffs.

 

thanks for the help all - appreciate it!

 

I went from the stock 32's to 305/70/16's - I've checked mine against 3 different GPS units and at 60mph on the speedo, it shows 60mph on the GPS. At 75, it shows 75... On all three GPS units (Garmin, TomTom, and Magellan) So I am guessing I just corrected the factory tolerance...

I also register 60mph on the roadside radar units when traveling at 60mph on the speedo.

Not sure if it would hold up if Chrysler were to question it, but I am confident with my speed.

 

Depending upon the specific tire, that makes sense, as the 305/70/16 is a 33-ish tire, so compared to the 32.1" oem tire, 33" nominal sizes can be less than an inch different....which, based upon the factory's 3% margin of error...the tiny < 3% difference between a 33 and a 32 can be easy absorbed by that margin...so that, in effect, the new tires corrected the prior factory margin of error, bringing the speedometer/odometer calibration to a dead nuts resolution.

That happend on another truck I had, the damn thing read high, I upped the tire size, and it read correctly...all due to the original factory variation.