Do people calibrate their speedometers right after getting bigger tires or have people just not calibrated right away?

[dylanpresley]

Question. Ive had my 2017 Ram 1500 for about 3 years now and it’s been on 37’s and a 6 inch suspension lift for about 2 years. Haven’t calibrated the speedometer and obviously the truck is very sluggish and the transmission stays at high rpm’s. I ordered the calibrator but the question is do people let their trucks go for that long without calibration and what is the effects of it?

 

[WY-Dave]

The calibrator won't do anything for the sluggish and rpms.
From my Jeep days, with the ABS and other electronic HAL adjustments, the speed difference may play into account.

 

[dylanpresley]

I’ve been looking at the reviews for this calibrator and folks are saying it helped their transmission shift points. They say it also helped restore some of the power that was lost with bigger tires. Just trying to figure out how far gone my truck might be lol

 

[olyelr]

Getting the tire size calibrated will certainly help some, mainly by getting the shift points back into check. But you will still have a much more sluggish feel when going from the stock 32’s-33’s to a set of 37’s. A regear would help with that dramatically.

 

[dylanpresley]

Getting the tire size calibrated will certainly help some, mainly by getting the shift points back into check. But you will still have a much more sluggish feel when going from the stock 32’s-33’s to a set of 37’s. A regear would help with that dramatically.

The calibrator tool asks me if I want to re gear. Will this do the job?

 

[olyelr]

The calibrator tool asks me if I want to re gear. Will this do the job?

No haaaaaaa, thats just to change the computer settings if you DO regear…which requires new differential gears.

 

[CanuckRam1313]

I switch from winter 17's (265/70R17) to summer 20's (295/65R20) and my speedo changes accordingly.

I adjust for the change and just roll with it.
I gauge the flow of traffic and run accordingly.

Perhaps one day I'll get HP-Tuner set up and really dial it in,. but for now, I just compensate and deal with it

 

[dylanpresley]

No haaaaaaa, thats just to change the computer settings if you DO regear…which requires new differential gears.

Oh ok. Thanks

 

[RamDiver]

I switch from winter 17's (265/70R17) to summer 20's (295/65R20) and my speedo changes accordingly.

I adjust for the change and just roll with it.
I gauge the flow of traffic and run accordingly.

Perhaps one day I'll get HP-Tuner set up and really dial it in,. but for now, I just compensate and deal with it

I played the neural compensation game for nearly 2 years before obtaining AlfaOBD and now the speedo is dialed in.

Both my summer and winter tires were off by a different amount and both would have short changed me on warranty mileage.

.

 

[olyelr]

I switch from winter 17's (265/70R17) to summer 20's (295/65R20) and my speedo changes accordingly.

No it dosnt.

 

[Nick@GotExhaust]

Calibrating for tire size will help shift points which will keep the truck in the right gear to help it not feel as sluggish. A regear will help that even more so. Not sure what engine, trans, and gears you have now but a regear may be the real fix for your 37's causing the truck to feel sluggish.

 

[CanuckRam1313]

No it dosnt.

Let me rephrase my statement.
I am aware that it doesn't automatically recalibrate itself when I switch tires.
What I should have said is that "I" account for the changes accordingly

But I do appreciate you correcting me.

However, I did include this in my post, too:
"I adjust for the change and just roll with it.
I gauge the flow of traffic and run accordingly."

 

[olyelr]

Let me rephrase my statement.
I am aware that it doesn't automatically recalibrate itself when I switch tires.
What I should have said is that "I" account for the changes accordingly

But I do appreciate you correcting me.

However, I did include this in my post, too:
"I adjust for the change and just roll with it.
I gauge the flow of traffic and run accordingly."

Yea i understand just doing the calculations and figuring out how much percentage your speedo is off and go that route. I was just saying that the truck wont automatically do that and have a correct speedo. Shift points will also be off.

 

[Quick_Shifter]

(For educational Purposes regarding this thread)
The 4th gen trucks seem to pick up the shift points faster even though the tcm will still need some miles to relearn. Side note on the 5th gens we clear the tcm and let it relearn right after the tire calibrations. They seem to need a push. Back in the day "lol" my year 2012 with the 6 speed trans never had problems hunting for gears with 37's and calibrating the tire size did not make any noticeable difference

 

[ram1500rsm]

Wow looking at the sig in the OP the truck is a 3.6L, and the OP hasn't posted what gears. Don't know about the V6's behavior in our trucks. What gear ratio do they have stock, 3.21 or 3.55?
37's will suck with this configuration and calibrating the speedometer won't fix the sluggishness. Will make the trans shift a little better sure, but it won't fix the issue with having the wrong gearing with big tires.

 

[62Blazer]

In regards to any sluggishness, recalibrating the speedo will do absolutely nothing for initial take off from a start. You take off in 1st gear regardless and there are no shift points or anything to change. Now once you get going and shifting up and down through the gears it can help some...it's usually nothing dramatic, but it is optimizing the shifting. From my experience the newer (well, within the last 20 years...) electronically controlled transmissions behave pretty good with larger tires. Older auto transmissions did have more of a tendency to hunt-shift, meaning they would shift back and forth between two gears every 5 seconds in some situations. Usually between the two top gears (like OD and D) on the freeway when climbing hills.

 

[RamDiver]

deleted

 

[Atcer2018]

Wow looking at the sig in the OP the truck is a 3.6L, and the OP hasn't posted what gears. Don't know much about the V6's but what gear ratio do they have stock, 3.21 or 3.55?
37's will suck with this configuration and calibrating the speedometer won't fix the sluggishness. Will make the trans shift a little better sure, but it won't fix the issue with having the wrong gearing with big tires.

You got that right! I have a 3.6 and going from the stock 33” SRA OEM street tire to E load 34” tire WITH a Speedo recalibration it is still noticeably less zippy after first gear.