NEW TIRE SPEEDO CALIBRATION?

[Joeyp]

Gotcha...I ordered mine with a 392 gear ratio but I honestly haven't noticed a difference in shifting before and after the RC calibration. It definitely fixed the speed, MPG and odometer though so I guess it just depends if you want it to be accurate or not. I'm just going by what the buzz is and trying to figure out if it makes an actual difference with the transmission.

For some reason my OCD isn't bothering me being off a couple miles per hour..Honestly with the 35's my truck is happy at 70 or 75 mph anyhow. Your truck looks great...Did you get the coilovers?

 

[ant0064]

For some reason my OCD isn't bothering me being off a couple miles per hour..Honely with the 35's my truck is happy at 70 or 75 mph anyhow. Your truck looks great...Did you get the coilovers?

Lol my OCD made me purchase the RC Calibrator! Thanks man...no coilovers, just the standard 6" ProComp lift.

 

[RodRow]

The ECU monitors driving habits over a number of shift points and adjusts shifting accordingly. AFAIK, the only difference in shifting you’ll feel is while the ECU is “relearning” the RPMs and speed at which you let off the accelerator once you have an accurate odometer reading. If you don’t change the way you drive, I don’t think you’ll notice.

 

[SColang22]

What is everyone using to re-calibrate their speedometer after changing to a non-stock tire size?
I recently added some and would like to know exactly how fast I'm going.

Pulsar will do it but I don’t think we need to. I went to 35s and I had multiple GPS speedos read the same as my dash after I put the 35s on and before I reprogrammed it

 

[ExcursionDiesel]

Pulsar will do it but I don’t think we need to. I went to 35s and I had multiple GPS speedos read the same as my dash after I put the 35s on and before I reprogrammed it

I don't see how that is possible.

 

[SColang22]

I don't see how that is possible.

Unless the computer can learn it I didn’t know either but 3 gps calculators where on with my speedo

 

[chad202]

I've had 33s for over a month and it's still off. Don't think its possible for the computer to learn as there's no sensor attached to the outer diameter of the tire. Even if the TPMS had such sensor it still wouldn't know the tire size.

 

[RodRow]

I've had 33s for over a month and it's still off. Don't think its possible for the computer to learn as there's no sensor attached to the outer diameter of the tire. Even if the TPMS had such sensor it still wouldn't know the tire size.

Completely agree. It’s impossible to change the tire from stock to a larger or smaller tire and have the truck “intuit” the change.

 

[SColang22]

Completely agree. It’s impossible to change the tire from stock to a larger or smaller tire and have the truck “intuit” the change.

Guys I'm just telling you what 3 different GPS's confirmed. It read the same after I changed my tire size as well.

 

[chad202]

Guys I'm just telling you what 3 different GPS's confirmed. It read the same after I changed my tire size as well.

Di you happen to check your speedodemeter vs this calibrated GPS before changing tires?

 

[SColang22]

Di you happen to check your speedodemeter vs this calibrated GPS before changing tires?

3 different GPS and yes. All measurement had the speedo 1 mph faster than the GPS. I'm not saying this isn't weird but its what I got. If anyone got anything different I'd love to hear it.

 

[ant0064]

3 different GPS and yes. All measurement had the speedo 1 mph faster than the GPS. I'm not saying this isn't weird but its what I got. If anyone got anything different I'd love to hear it.

Mine was off by 4-5 mph at higher speeds after switching to 35's, and drove on them for a couple weeks before I re-calibrated. It's physics, no idea how you were the exception to the rule lol.

 

[SColang22]

Mine was off by 4-5 mph at higher speeds after switching to 35's, and drove on them for a couple weeks before I re-calibrated. It's physics, no idea how you were the exception to the rule lol.

I have no idea. I tested it with my buddy who put the tires on and it came out the exact same. I wish we could have found one of those police radar set ups to test it by.

 

[Joeyp]

Mine is off 3-5mph like ant0064's going from 265's to my 35's

 

[chad202]

Tires size calculator said going from stock to my 305s would increase speed compared to what speed odometer was reading by 1.84 mph. Well a normal height for a 305 is 32.8, the brand I bought says 32.7. My actual speed compared to odometer is 1.68 faster.

 

[ant0064]

I have no idea. I tested it with my buddy who put the tires on and it came out the exact same. I wish we could have found one of those police radar set ups to test it by.

GPS apps are pretty accurate I've found. I also tested the odometer from a known distance after I calibrated...it was off before and accurate after. Maybe give that a try...oddly enough I believe the digital speedo reading is inaccurate after a tire change, while the analog speed is accurate regardless of tire size. Could be wrong, but something to check out if you're only looking at the analog dial. However, the odometer, mpg and speed ratings are all digital so that's what all these things are calculated from. Again could totally be wrong but it's something I thought I observed before I calibrated.

 

[SColang22]

GPS apps are pretty accurate I've found. I also tested the odometer from a known distance after I calibrated...it was off before and accurate after. Maybe give that a try...oddly enough I believe the digital speedo reading is inaccurate after a tire change, while the analog speed is accurate regardless of tire size. Could be wrong, but something to check out if you're only looking at the analog dial. However, the odometer, mpg and speed ratings are all digital so that's what all these things are calculated from. Again could totally be wrong but it's something I thought I observed before I calibrated.

Yea when I tested it I just set cruise control to 70mph on as flat a highway as I could find and had the 3 GPSs set up. I have since programmed it with the pulsar but maybe ill try to revert it back to the stock size and try it again. I found it super weird that everything read pretty much the same. 1mph difference on the GPS is not a big difference

 

[nicodywill]

Mine was off by 4-5 mph at higher speeds after switching to 35's, and drove on them for a couple weeks before I re-calibrated. It's physics, no idea how you were the exception to the rule lol.

This was the exact same case for mine as well. I confirmed and adjusted using 3 different GPS speedo apps.

Yea when I tested it I just set cruise control to 70mph on as flat a highway as I could find and had the 3 GPSs set up. I have since programmed it with the pulsar but maybe ill try to revert it back to the stock size and try it again. I found it super weird that everything read pretty much the same. 1mph difference on the GPS is not a big difference

I can't think of any way this is possible, unless your pickup's speedo wasn't reading correctly in stock config.

 

[psyberai]

I changed my stock tires from 275/65R18 to 275/70R18 which is basically going from 32.1" to 33.2". I noticed a delta between Waze and truck speedo of about 2-3 MPH. Bought the RC Speedo Calibrator (the dealership recommended HyperTech, but I thought I would try the cheaper option since they seemed similar in advertised functions). Hooked it up and calibrated for 33.25--> it was still off. So based on what others had experienced, I kept calibrating down until I ended up at 32". I see less than a .5 MPH delta, really an almost negligible difference. After setting the cruise control for 70, Waze seems to fluctuate at 69-70 while the speedo reads a solid 70.

 

[deanfx]

With the RC speedo tool do I need to unplug all the fuses in the instructions or just do it?