I just purchased 20"lariat wheels for my 2015 xlt f350 super duty. Which are all OEM including the rubber. The tire size did increase. I was hoping the livewire ts tuner would correct the speedometer but it did not. I compared it to my gps and my phone. Have tested it before i changed the tires and everything matched. I have already reached out to 5star tuning about this. Has anyone ran into this issue?

 

I just bought an 08 with the 6.4 that was rolling on 37s. It also has an SCT tuner. The speedo was out by 20kmh! I ditched the 37s for some 35s and then adjusted the revolution per mile setting in the tuner. I was now out by about 7kmh. That could be because of the tire swap? I did another adjustment but haven't driven the truck yet to see if it changed. I have been searching the net about this. Some people say it does adjust speedo others say it only adjusts tranny shifting based on tire size! I don't know the answer yet.I have an SCT livewire TS 5015.

 

I found out that SCT does not support changing the tire size on the newer SD yet

 

Same issue here, I have been playing with different tire settings, and axle ratio settings. The closest I have gotten it was for 315x70x17 tire and 3.73 axle was 2 mph slow on on speedo, using the settings 3.55 axle and a 34.4" tire. But it seems my truck start shifting hard and the tranny gets confused what gear it's in... so I switched it back to the 3.73 axle and 34.4" tire and at 75mph it's off by 5mph slow.

 

My sct x4 doesn't correct the speedo either. I was less than thrilled with my tuner purchase being it does nothing of the things I asked when I called before purchase. I didn't buy it for the tunes.

 

I contacted SCT about it. They said the update should be coming out soon for us

 

Same here. The SCT tuner did not correct my speedo in any fashion I tried. I went up in tire size and that did it.

 

good to hear!!

 

Awesome, I'm glad someone bit the bullet and called them haha. Now let's see if they make good on it.