I'm hoping that with all the owners on here that have 35s on their H3s, this should be a relatively easy question to answer...

I have a 2008 base with the 3.7 and 4 new 315s on her. Can you share about how many mph the speedo is now off? And what I need to do to get it recalibrated? Thanks!

 

Could be anywhere between 6-8% off depending on the actual height of the tires you had installed.

PCMofNC.com can fix the calibration for ya and tune it up to get back some of the power you lost going to 35s.

 

a cheap gps gives pretty accurate speed info.
in fact very accurate

 

or u can get a scan gauge 2..

 

I have 35's, never gave what is does to the speedo a second thought. Why the concern?

 

Pretty sure the ScanGauge is going to report about the same as the speedo based on the original tar size.

 

ahh, yeah, the sg2 would use obd2 like the speedo does

 

I didn't think about that.. And I have my pcm tuned also. duhhhhhh lol

 

I tuned the PCM for performance not 35 inch tires, my speedo is not my concern, if I am doing 30mph or 6-8 percent difference was not why I did the PCM for less. I posted a comment, most guys ask a lot of questions, I gave an honest answer. No need to be a smart ***. I do a lot of towing and the PCM tune was to wake the truck up, for and 8 cylinder truck it tows just OK. My wifes 8 cylinder Pathfinder tows my camper and boat like it is nothing, the H3 does not. Hence the tune, cutback and airDoc. The 35 inch tires do not help but even with 33 inch tires the result was not that much different. The rock rails and UCP are for hunting in the woods, get hung up on a lot of crap, I use my truck as it is intended for and it shows, it is not a garage queen or mall queen.

 

When you order a PCM tune, you can tell them your tire size and they will include that with the tune parameters to re-calibrate the speedo.


If you are going to run 35s with an I5, you will most definitely want a tune. You may also want other performance mods to offset the power loss you will experience by changing your final drive ratio with the 35s, like an intake, Cat back exhaust, PP TB, Efan conversion. For an 08+ you would need a PCM tune to control the fan. The tune can be tailored to whatever mods you do.