Speedometer recalibration
 

I have a 2011 LS and I put 255/35/20 tires on my can which threw off the speedometer by 3-4 miles. I purchased the Hypertech speedo calibrator but that thing is a joke, after a month of dealing with Hypertech they were unable to get it working on my car so i sent it back. Does anyone out there know any alternate companies that can recalibrate my speedometer? I currently reside in the Mesa, Arizona.

Dyno it.. All tuners should be able too