Speedo reading false speed

[Jac0b]

Hello all,

Short story, bought a lifted truck thought I’d like the lifted style turns out I didn’t. Found someone who was willing to trade lift for stock height. Now instead of running 37” tires I’m running metric 305s (33.2”), and the speedo showing 10 miles faster than what I’m going. Anyone know any tricks to plug into the truck to get it reading correctly, or run into this problem?

2012 Ram 2500 6.7L
EFI Live single tune imbedded in cpu
Deleted (egr, dpf), cold air intake, 5” exhaust turbo back
20x10 Moto metal wheels
Wrapped in LT305x55x20 nitto terra grappler g2


Thanks.

 

[RedSRT4Me]

Most of the newer hand held tuners can do it.

Alfaobd can do it although I haven't tried yet. Just saw the function in it the other day.

 

[Jac0b]

What about linking a edge cts2 with efi live would I still be able to do the tires? And I’ve heard that sometime you’ve gotta play with the numbers meaning, you have to put bigger or smaller tires into the programmer to get the speedo just right. Any insight on this?