Bigger Wheels & Tires computer change.

[Bocaloco]

So I threw on new 20” wheels wrapped in 295/65R20’s Radar Renegades. I just received my Procal Snap in the mail today and was wondering if anyone has done the recalibration so the speedometer & odometer are corrected? Looks pretty straightforward.

 

[dslbrnr]

Mines off about 6-7 MPH with 37's. I was wondering the same. The dealers used to program for free but doubt it now days

 

[AH64ID]

Mines off about 6-7 MPH with 37's. I was wondering the same. The dealers used to program for free but doubt it now days

Get AlfaOBD (Android) or JScan (iPhone), plus the security bypass cable and a VLinker MC+ and adjust your speedo yourself.

Cheaper than a procal snap and a much better tool.

 

[Wholeo]

I used the Pro Cal Snap on my 22, it was easy. It has been a while since I did it, but I do remember when I changed the tire pressure I did not get the 2 or 3 horn honks like I did during initial set up and for speedo change conformation as stated in the directions. Must of tried 10 times waiting for the horn honk conformation, finally gave up not realizing the change did take without the honking conformation. For 37's I set my tire size to 35.5 inches, and it was spot on according to a speedo app and Google Maps.

 

[Bocaloco]

Mines off about 6-7 MPH with 37's. I was wondering the same. The dealers used to program for free but doubt it now days

Well……I went back and forth down a road where I could get the speed up and got it dialed in to just 1 mph off. Measuring my tire from the ground up, and I used a level to make sure I was good, it measured 34.1”. Well what got me dialed in was setting my numbers going to 31.6 inches. So my speedometer now shows 1mph faster than the gps speed and that’s just fine. Id rather show slightly faster then slower. Keeps the cops off my ass.

Are you showing faster on your speedo? Also, what are you using to Calibrate it with? The ProCal Snap that I bought is easy. It still threw a Check engine light though and it’s now not showing my TPMS info. I contacted the company and they said just drive it and the light should go out on its own.

 

[dslbrnr]

Mine shows slower than I'm driving so I keep it 6-7 MPH under the speed limit. I'm not much of an electronic guy but I checked out the JScan AH64ID mentioned and the Pro Cal Snap.
All good stuff I wasn't aware of, appreciate the info!

 

[AH64ID]

Well……I went back and forth down a road where I could get the speed up and got it dialed in to just 1 mph off. Measuring my tire from the ground up, and I used a level to make sure I was good, it measured 34.1”. Well what got me dialed in was setting my numbers going to 31.6 inches. So my speedometer now shows 1mph faster than the gps speed and that’s just fine. Id rather show slightly faster then slower. Keeps the cops off my ass.

Are you showing faster on your speedo? Also, what are you using to Calibrate it with? The ProCal Snap that I bought is easy. It still threw a Check engine light though and it’s now not showing my TPMS info. I contacted the company and they said just drive it and the light should go out on its own.

Most tire manufacturers publish rev/mile data on their tires, use that info. Tires don’t roll round, so ground to top is always taller than rolling diameter.

I always recommend setting tire size based on odometer reading, not speedometer reading. Then speedo is already calibrated to show you faster than your going and faster then the odo is recording, at least on every rig I’ve checked in the last 20 years. Don’t want to eat any warranty up too fast on purpose.

1mph at what speed? With a setting that small I’m guessing it’s a couple percent off still.

The fact that you lost TPMS signals and got a CEL is a little concerning. The CEL may extinguish, but there will still be a record of it not being cleared. Doesn’t leave a lot of faith in the Procal, especially for its price.

 

[DrTron]

I always recommend setting tire size based on odometer reading, not speedometer reading.

I did it using a GPS unit not connected to the truck (like Waze would be), because apps like Waze get their speed information from the truck, which is exactly not what you want.
Got it dialed in pretty much dead on after a few tries. At least those radar-speed-checking displays one sees occasionally usually show exactly what my speedo says.

 

[AH64ID]

I did it using a GPS unit not connected to the truck (like Waze would be), because apps like Waze get their speed information from the truck, which is exactly not what you want.
Got it dialed in pretty much dead on after a few tries. At least those radar-speed-checking displays one sees occasionally usually show exactly what my speedo says.

In my experience, Waze does not get its speed from the truck.

Waze is how I knew my speedometer was off from the factory.

 

[Bocaloco]

Most tire manufacturers publish rev/mile data on their tires, use that info. Tires don’t roll round, so ground to top is always taller than rolling diameter.

I always recommend setting tire size based on odometer reading, not speedometer reading. Then speedo is already calibrated to show you faster than your going and faster then the odo is recording, at least on every rig I’ve checked in the last 20 years. Don’t want to eat any warranty up too fast on purpose.

1mph at what speed? With a setting that small I’m guessing it’s a couple percent off still.

The fact that you lost TPMS signals and got a CEL is a little concerning. The CEL may extinguish, but there will still be a record of it not being cleared. Doesn’t leave a lot of faith in the Procal, especially for its price.

1 mph within all speeds according to the GPS speed & the Speedometer.

I contacted AEV (ProCal folks) and the guy told me that they have had a few people report the same thing, and said to just drive the truck and it should clear on its own.

I did it using a GPS unit not connected to the truck (like Waze would be), because apps like Waze get their speed information from the truck, which is exactly not what you want.
Got it dialed in pretty much dead on after a few tries. At least those radar-speed-checking displays one sees occasionally usually show exactly what my speedo says.

 

[AH64ID]

1 mph within all speeds according to the GPS speed & the Speedometer.

I contacted AEV (ProCal folks) and the guy told me that they have had a few people report the same thing, and said to just drive the truck and it should clear on its own.

1 mph at all speeds indicates that the tire size is likely accurate, but just reads fast. A speedo error from the wrong tire size is a percent, so varies with speed.