Larger Tires and Speed Correction - Who Has Done it?

[HTX1811]

I have Nitto Ridge Grapplers 255/80/R17 tires. Measure 32 5/8" tall. My speedo according to a GPS speed app is off by the following:

Speedo MPH - GPS MPH - Difference
40 - 44 - +4
45 - 50 - +5
50 - 56 - +6
60 - 66-67 - +6-7
65 - 72-73 - +7-8
70 - 78 - +8
80- 88-89 - +8-9
90 - 98-99 - +9

Sometimes it bounced between two speeds thus the two numbers.

Has anyone used a tuner to adjust for larger tires? If so, what brand? SCT says no such luck and no timeframe for when they will be able to.

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[Jason@Stage3]

I have Nitto Ridge Grapplers 255/80/R17 tires. Measure 32 5/8" tall. My speedo according to a GPS speed app is off by the following:

Speedo MPH GPS MPH Difference
40 - 44 - +4
45 - 50 - +5
50 - 56 - +6
60 - 66-67 - +6-7
65 - 72-73 - +7-8
70 - 78 - +8
80- 88-89 - +8-9
90 - 98-99 - +9

Sometimes it bounced between two speeds thus the two numbers.

Has anyone used a tuner to adjust for larger tires? If so, what brand? SCT says no such luck and no timeframe for when they will be able to.

We used HyperTech's Speedo Calibrator on our Ranger. It worked perfectly.

When you add bigger tires (and/or gears for that matter) you speed gets thrown off by a percentage, hence why your GPS may show a fluctuation as it rounds up and down.

We only had one hiccup in that our HyperTech was married to an F150 that was long gone. Luckily, HyperTech was able to unlock the device for us with an update. A brand-new unit won't have that problem.

 

[HTX1811]

Any chance to push any type of custom tune to a SCT unit to adjust for tire size?

If not, it looks like $229 to buy a Hypertech from y'all.

 

[Jason@Stage3]

Any chance to push any type of custom tune to a SCT unit to adjust for tire size?

If not, it looks like $229 to buy a Hypertech from y'all.

Unfortunately, SCT's support for tire size adjustment is usually at the device level, and a custom tune will not likely be able to help, unless it's only certain strategies that SCT hasn't cracked yet.

I shot 5-Star an email about the nGauge, though. I'll let you know what they say.

 

[RedlandRanger]

If you have FORScan, there is a thread discussing how to make the change using it:

https://www.ranger5g.com/forum/threads/forscan-speedo-calibration-for-larger-tires.4200/

 

[Msfitoy]

I have Nitto Ridge Grapplers 255/80/R17 tires. Measure 32 5/8" tall. My speedo according to a GPS speed app is off by the following:

Speedo MPH - GPS MPH - Difference
40 - 44 - +4
45 - 50 - +5
50 - 56 - +6
60 - 66-67 - +6-7
65 - 72-73 - +7-8
70 - 78 - +8
80- 88-89 - +8-9
90 - 98-99 - +9

Sometimes it bounced between two speeds thus the two numbers.

Has anyone used a tuner to adjust for larger tires? If so, what brand? SCT says no such luck and no timeframe for when they will be able to.

Yes...Forscan...

Wow that's really off...I have 285/70-17 and were off +4 mph at 70 mph....corrected now +1 over GPS...perfect...

 

[Jason@Stage3]

Any chance to push any type of custom tune to a SCT unit to adjust for tire size?

If not, it looks like $229 to buy a Hypertech from y'all.

According to 5-Star, SCT is still having trouble.

However, the nGauge can tune for tire size on the Rangers.

 

[Maltese]

+1 on ForScan used that and my garmin watch for speed and it is pretty much dead on

 

[HTX1811]

Do not have FORScan. Are they VIN locked or would someone around the Houston area for a fee be able to use their's to adjust my tire size?

EDIT: I am researching them now. Not terribly expensive.

 

[Maltese]

you can use the demo version for free to get it done, then pay if you want to tinker more

edit: yeah you got to buy the dongle, but it has other uses too for around 50 or so

 

[HTX1811]

I have been reading this thread: https://www.ranger5g.com/forum/threads/forscan-speedo-calibration-for-larger-tires.4200/

Seems you still get a code, not a cel, with FORScan but a code. Or spend $229 and have no codes and adjust for size via the Hypertech. Seems maybe worth it to me for a simple plug and correct instead of having to mess with codes to correct tire size and get a code.

 

[RedlandRanger]

you can use the demo version for free to get it done, then pay if you want to tinker more

edit: yeah you got to buy the dongle, but it has other uses too for around 50 or so

The OBDII port connector is between 20 and 30 dollars depending on which one you purchase. FORScan can be used indefinitely with the free license - you just have to get a new key every 2 months. If you use it that much, you probably should support the project.

 

[HTX1811]

Looks like I am going with the Hypertech from Stage3.
One question before I pull the trigger. Since I have an SCT tune on the truck, would I have to return to stock with the SCT, then use the Hypertech to adjust tire size, then re-install the SCT tune? In doing that, would the tire size adjustment stick?

Hope your folks in Utah are ok. My winch I ordered from y'all was coming from Utah and was advised today it was delayed due to the earthquake. Understably so. Again, I hope everyone is ok.

 

[HTX1811]

My new tires are 32 5/8" tall compared to the factory size was maybe a hair over 28".

Yes...Forscan...

Wow that's really off...I have 285/70-17 and were off +4 mph at 70 mph....corrected now +1 over GPS...perfect...

 

[Msfitoy]

My new tires are 32 5/8" tall compared to the factory size was maybe a hair over 28".

That's about the same as mine...hmmm

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