Changing tire size, how to adjust mph's???

[srkpaco]

I have a 2004 LC all stock with cracked torsion bars and no running boards. I am changing tire size from 275/60/R18 to 275/65/R18. I know it will change the mph's to show I am going slower than i really am. How do you adjust this? I assume you plug it in and do it with a computer, can the dealership or my local garage do this? Of do I have to but some special tuner?

Thanks

 

[petrotk40]

http://www.roadkillcustoms.com/hot-...r-Calibration-Tire-Size-Change-Calculator.asp

the change is so small, it's not worth messing with. You are talking about 2 mph @ 70mph

also, keep an eye on this thread
https://forum.ih8mud.com/100-series...alling-generic-marks4wd-speed-calibrator.html

 

[AimCOtaco]

I use a scan gauge II, it allows you to put an offset in for the speed, helps accurize the mileage data as well. (your speedo will stay the same but you now have a corrected digital speedo)
Then, when smokeys on my tail I keep and eye on the scangauge MPH.

 

[Anthony.L]

I use a scan gauge II, it allows you to put an offset in for the speed, helps accurize the mileage data as well.

Ditto, scan gauge mounted on the steering column. 6-7% correction is common depending on tire size. Dial in the correction on the ScanGauge then confirm with GPS (iPhone, iPad, Garmin, etc).

Here's mine installed, 2 years and still love it. Added benefit, digital gauge for transmission temp, water temp, and alternator voltage. The picture was just after install, and before I changed the gauge options.

 

[srkpaco]

i usually don't like adding electrical gadgets to my rig to many issues can arise. Is there no way to adjust the speedo that is in the car with a computer or at the dealership?

 

[Anthony.L]

i usually don't like adding electrical gadgets to my rig to many issues can arise. Is there no way to adjust the speedo that is in the car with a computer or at the dealership?

Not that I'm aware of, but feel free to ask and report back if you find something!

As for adding gadgets and issues, did you even look at the ScanGuage install? It's one cable that plugs into the OBDII port. A 4 year old can complete the install, and it's impossible to mess anything up.

 

[AimCOtaco]

Study up, the Scangauge it is also an OBD code reader/re-set tool that ONLY connects to the OBD2 port, install takes about as long as plugging in a lamp. Mine has paid for itsef in fuel savings and diagnostics many times over. It's also usable on any north american vehicle since like 1995. Pretty much a zero risk install and lots of gains.

In order to fool the gauges you will be cutting wires and hacking in a 3rd party component. I don't think there is any dealer calibration available. If there is you get to pay them every time you change tires, gears, etc.

Hope you find a solution you are happy with.

 

[hoser]

I have a 2004 LC all stock with cracked torsion bars and no running boards. I am changing tire size from 275/60/R18 to 275/65/R18. I know it will change the mph's to show I am going slower than i really am...

Check your actual speed against a portable GPS or even phone app. Your speedometer might actually be more accurate now than with the original size.

 

[1loudLX]

if you had 4.30 gears stock I'd have said get 4.88s and 35s, no correction needed.