Just added a 2" leveling kit & plan on upgrading from 275/55/20's to 275/60/20 just a hair taller. this will effect the speed & shifting points. I spoke to one dealer & he told me I didn't need to change anything the tires are the same size. would anyone provide some guidance. should I have the dealer make the tire change in the computer or purchase a box and have the ability to make some adjustments my self. if so which brand?

 

The 275x60's are 1 inch taller then the 275x55's. Not enough to worry about. My GPS shows 1 mph off so I'm not fooling with it. These tranny's seem to have a mind of their own and need to be re-programmed every now and then no matter what size tire you're running. That's where a programmer comes in handy!