Dwayne,
I posted an item a couple of months ago about the great service I got from Superlift on their TruSpeed calibrator. Basically mine failed, and Superlift replaced it free with no questions. Very impressive.
You can see my post regarding their service here:
https://www.turbodieselregister.com/forums/showthread.php?s=&threadid=78623
You can see the calibrator here:
http://www.superlift.com/products/misc/truspeed. asp
You can buy it from Rickson here:
http://www.ricksontruck.com/speedometer.html
As you probably know from this web site, Rickson enjoys an excellent reputation for customer service too. They have always treated me better than I would have expected. Another great company.
I like the TruSpeed calibrator, but it's expensive. There are not too many devices out there that will do the same job. It wires up in-line with your wire from the rear wheel speed sensor and adjusts the signal to the truck's computers. My two (original and replacement) have been on the truck for a couple of years now and have never set any fault codes, nor illuminated any lights. The 4-wheel ABS still works fine.
If you have just 2-wheel ABS rather than 4-wheel, Rickson sells another unit you can use. I can't comment on that one though.
Having said all that, it's my understanding that if you have installed a tire size that was available from the factory as original equipment, you can have the Dodge dealer reprogram your on-board computer to correct for the new tire size. This is available only for tire sizes that were available from Dodge, I think. Others here will know for sure.
You can search for more information on speedometer corrections, or check with your Dodge dealer.
Good luck.
Loren