Programmable speedometer for different tire sizes?

[Lcubed]

with the large variety of tire sizes (and potential tire swap outs for offload vs on-road, etc),
will the end user be able to set the tire size so that the speedo displays the correct speed?

last thing i want to do is visit the dealer for 'programming'

i could easily see myself swapping the 33 AT tires on the bad lands for more aggressive 35" MT
tires when wheeling for the weekend. or swapping from the MT's to a shorter, more sized tire
for snow/winter use.

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[jtzako]

I've never had a vehicle with an easily reprogrammable speedo. I think it'll be off by 3-4 mph at 65mph though. I'm used to it on my current vehicle (its off by a similar amount)

 

[MJJ]

The speedometer will be calibrated to whatever tire size was delivered on the vehicle. If you order the Sasquatch package the speedo will be calibrated for that tire size.

If you were to change tire size in the aftermarket, then it would need to be re-programmed. Not sure Ford can/will do that. I know if you have a separate hand held tuning device like SCT you can adjust the tire revolutions but that can may come with some risk.

Or you can just live with the fact that the speedo will be off. The general rule of thumb as I recall for every inch difference in tire height it impacts the speedo by approx 2 mph. So if changed from a 33 to a 35 in theory your speedo would be off by about 4 mph. I say that in theory because not all tires measure exactly the same as they are listed. Tire Rack has great tools to look up the exact differences between tires in regards to specs.

Personally i would not crack the on board unit just to adjust tire revolutions.

 

[Lcubed]

OP here.

fwiw, for the current generation VW golf, the tire size can be adjusted for vw factory tire sizes using VCDS or android based OBDEleven2. or you could go to the dealer...

there are plenty of speed cameras in my neighboring city (which also dropped the
non-posted speed limit to 20 from 25!)

 

[timhood]

I was thinking the same thing. We might be getting a model with a more off-road oriented tire and want to get some "street" tires to avoid noise, worse fuel economy and wearing out all-terrain tires with daily street use. @MJJ said 2 inches could be 4mph difference. That's an extra 6,667 miles clocked on the odometer in 100,000 miles. Miles I didn't actually drive. ?

 

[Toccoa]

Did someone say speedo?

 

[Zinn]

Did someone say speedo?

^ haha!

It would be great if you could just adjust it in the vehicle settings - wouldn't surprise me if Ford included a user setting for that.

When I put a Ford Performance tune on my Mustang I was playing around in the ProCal software and there was a setting to choose tire diameter for "speedo" calibration. So it's definitely possible to do yourself if you have tuner software, but at least with Ford Performance that will probably be 18 months out from when the Bronco is first available. I'm sure the dealership could do it in the meantime, but a tuner would be one of the first things I buy so I can change the settings myself.

 

[Dr.Z]

New to the off road game,
how horrible would it be to have 315/70 on a Daily driver. I’ll get her to some off roading here in the desert and on hike etc. I love the look of the 2 inch lift and beefier tire... but I make educated decisions .

thoughts ?

 

[EcobeastRyan]

Perhaps using forscan it can be changed

 

[Nickp]

New to the off road game,
how horrible would it be to have 315/70 on a Daily driver. I’ll get her to some off roading here in the desert and on hike etc. I love the look of the 2 inch lift and beefier tire... but I make educated decisions .

thoughts ?

I daily a 33” tire and wouldn’t have any trouble with a 35”. My buddy’s Jeep with 37’s... yeah that would take a bit more dedication. But it had a 4” lift too so it was just super tall getting in.

 

[HoosierDaddy]

This is like deja Vu...been dicussed already.....recently.
Other Fords I have dealt with, recalibrating the speedo is a very simple process.
The vehicle speed is derived from the antilock brake system constantly monitoring wheel speed.
Part of that calculation is the "Revolutions per Mile" of any given tire size.
Look it up under the given tires specs.
There will be a field that can be changed in the braking systems programming to input the new wheel size RPM(mile)
PRESTO! Properly calibrated speedo...meter.
Takes a Ford tech about 10 minutes.

 

[Parker]

Here is a great little tool for tire musings:

https://www.tacomaworld.com/tirecalc?tires=315-70r17-285-75r17

This calculation is my fantasy for upping Black Diamond suspension and then de-tuning it for good all around A/T use.

 

[vrtical]

Forscan is used in the F150 camp

 

[Lcubed]

Forscan is used in the F150 camp

can the lite version do the job or does it require the laptop based version?

 

[Cyclone]

Keep in mind bigger tire registers less miles on the odometer and reads a lower than actual speed.

Smaller obviously has the opposite effect.

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