2nd Gen Non-Engine/Transmission smarty speedo setting

[DIESELWRKS]

I have 315/70/17 diameter of 24. 6 and 3. 54 rear gears trying to find the setting on smarty to correct the speed. does anyone have the closest speed value setting. thanks



2002 HO 6-SPD LB 4X4 QC HTT 62/14 SB-FE SMARTY TST PM3 MACH 4'S, RINGED AND STUDS, AFE/2"SILVERLINE D/PRICOL PYRO,BOOST,FUEL

TURN-OVER BALL, RIDE RITE AIR BAGS. FASS 150 W/DONALDSON FUEL FILTER, VULCAN 1/2 DRAW-STRAW, VULCAN 3/8 FUEL LINE AND FITTINGS, DSS 03 TRAC-BAR DSS BOX SUPPORT 17'' KMC BLACK HOSS, 315/70/17 MICKTHOM BMTZ'S 6" RCD LIFT COUPLE OF STUPID STICKERS AND DE-BADGED FOR FUEL MILEAGE.

 

[Bob4x4]

I am pretty sure you want more like 34. 5 not 24. 6 for a 315

Bob

 

[DIESELWRKS]

oops

typo 34. 6 is tire spec. so still need to find smarty setting 35. 00 is off and 34. 75 is off and 34. 50 is off on speed

 

[WTBurke]

I haven't played with that as of yet. I have the SuperLift speed corrector doing it's job for my 37's but, I did speak with Bob Wagner last week on Friday and I asked about this feature. He told me the SMARTY will make 1/4" corrections. Perhaps I misunderstood him?



My previous GoodYear MTR's were 315's and I too belive 34. 5" is the size.



I too will be using the SMARTY for the correction as I wish to remove the SuperLift device.



William

 

[rd3]

I set mine at 34. 36, it seems to be good by my GPS. I found this number on a tire site.

 

[AKaiser]

I don't know why, maybe it's chrysler error, but I had to really play with mine to get it to match the mile marks on the speedometer test area on US 31 south of Franklin. It's pretty accurate now.

 

[MrDiesel]

I've been playin with mine too... I have Swamper IROK 35s, I've gradually bumped my Smarty down to 33. 5 and it still is off at 60mph... .

 

[DIESELWRKS]

Thats a shame I like the smarty and one of the reason was the speedo tool but its not helping it sounds. well maybe Bill Wagner might chime in and help us. thanks for the replys

 

[Sixpack]

I have 315/70/17 diameter of 24. 6 and 3. 54 rear gears trying to find the setting on smarty to correct the speed. does anyone have the closest speed value setting. thanks



2002 HO 6-SPD LB 4X4 QC HTT 62/14 SB-FE SMARTY TST PM3 MACH 4'S, RINGED AND STUDS, AFE/2"SILVERLINE D/PRICOL PYRO,BOOST,FUEL

TURN-OVER BALL, RIDE RITE AIR BAGS. FASS 150 W/DONALDSON FUEL FILTER, VULCAN 1/2 DRAW-STRAW, VULCAN 3/8 FUEL LINE AND FITTINGS, DSS 03 TRAC-BAR DSS BOX SUPPORT 17'' KMC BLACK HOSS, 315/70/17 MICKTHOM BMTZ'S 6" RCD LIFT COUPLE OF STUPID STICKERS AND DE-BADGED FOR FUEL MILEAGE.

I set my tire size for my Toyo Mt 35x12. 5x17 @ 34. 25 and it was real close (1mph at the most off).

 

[Bob4x4]

Using the smarty to calibrate for tire size is easy,it will go out 2 decimal places to get it spot on. You will get it done quickly if you have a partner in the truck to watch the gps. Tire specs are off up to 10 %. The larger the tire the more wear will show up as you rack up the miles also.



Bob

 

[MrDiesel]

I don't think figuring out how to do it is the issue here, it's the accuracy of the device itself. I as well as some others do not have access to a hand held GPS. So I measured my tire from approx. the center of the hub to the ground, X2 and used that figure. It was WAY off. I'm still using the trial and error method and mile markers... .

 

[AKaiser]

It probably didn't help that the speedometer check course was improperly surveyed. That, or the first marker got hit by something, and was improperly positioned when it was replaced. I know mile markers on the interstate aren't exactly accurate, but across 100 miles, I have little discrepancy now, after dialing it in over several runs on the 5 mile speedo check. It's more accurate than "flash to bang" for my fellow artillerymen and weather watchers.

 

[NoSeeUm]

One tip that may help save some time, from what I discovered, is that you don't need to shutdown the engine to do tire size calibrations. In my case, I had to pull off the side of the road because I was always by myself. I am not sure if you could do it underway if you had a partner in the truck watching the GPS and setting the Smarty, but might be worth a try.



Jim

 

[Bob4x4]

I don't think figuring out how to do it is the issue here, it's the accuracy of the device itself. I as well as some others do not have access to a hand held GPS. So I measured my tire from approx. the center of the hub to the ground, X2 and used that figure. It was WAY off. I'm still using the trial and error method and mile markers... .

That is not the best way to measure... ... ... ..... Measure the circumference than do the math



Bob

 

[DIESELWRKS]

smarty

I don't think figuring out how to do it is the issue here, it's the accuracy of the device itself. I as well as some others do not have access to a hand held GPS. So I measured my tire from approx. the center of the hub to the ground, X2 and used that figure. It was WAY off. I'm still using the trial and error method and mile markers... .

I agree the smarty is great but, the speedo correction factor isnt the most accurate. I just think there is to much variables I guess some people it may work close for them and others like us its not cutting it. I dont think I should have to get a gps to dial in a program that is advertised to work correctly. so trial by error is the common it seems. this makes me wonder just how accurate compared to the smarty the dealership re-flash would be?

 

[Bob4x4]

I agree the smarty is great but, the speedo correction factor isnt the most accurate. I just think there is to much variables I guess some people it may work close for them and others like us its not cutting it. I dont think I should have to get a gps to dial in a program that is advertised to work correctly. so trial by error is the common it seems. this makes me wonder just how accurate compared to the smarty the dealership re-flash would be?

Again,tire sizing is not accurate. The industry standard is + or - 10 % on the sizing. A 37" tire will also lose a lot of size as the tread wears,again changing tire height and speedo accuracy



Bob

'























-_

 

[MrDiesel]

That is not the best way to measure... ... ... ..... Measure the circumference than do the math



Bob

That won't take into acount lower pressure. The tire won't be as tall on the truck as it is sitting by itself, especally at the pressures I run.

 

[DIESELWRKS]

Again,tire sizing is not accurate. The industry standard is + or - 10 % on the sizing. A 37" tire will also lose a lot of size as the tread wears,again changing tire height and speedo accuracy



Bob

'























-_

2002 HO 6-SPD LB 4X4 QC HTT 62/14 SB-FE SMARTY TST PM3 MACH 4'S, RINGED AND STUDS, AFE/2 "SILVERLINE D/PRICOL PYRO,BOOST,FUEL

TURN-OVER BALL, RIDE RITE AIR BAGS. FASS 150 W/DONALDSON FUEL FILTER, VULCAN 1/2 DRAW-STRAW, VULCAN 3/8 FUEL LINE AND FITTINGS, DSS 03 TRAC-BAR DSS BOX SUPPORT 17'' KMC BLACK HOSS, 315/70/17 MICKTHOM BMTZ'S 6" RCD LIFT COUPLE OF STUPID STICKERS AND DE-BADGED FOR FUEL MILEAGE. :-laf

 

[KAlder]

Best way to figure out the diameter of a tire is to measure its "rolling" diameter. Mark your tire on the closest point to the ground and that spot on the ground (so you have a line that runs through your tire and onto the ground). Drive in a straight line for 3 or 4 revoloutions. Stop when the mark on your tire is at the ground again. Measure the distance between your mark on the ground and the mark on your tire. Divide that by the rotations your tire took to get there. Then divide that answer by 3. 14 (pie).



So, for example: You made your marks, drove forward so the mark on your tire made 4 revoloutions, and measured 412 and 1/4" (412. 25) between the marks. The math should look like this: 412. 25 Divided by 4 = 103. 0625 divided by 3. 14 (pie) = 32. 82245222929936305. Your tire is 32. 82245222929936305 inches tall.



The more revouloutions you use the less error you will have. This is how I have always set the pinion factor (tire size and/or gear ratio settings) with the DRBIII, and it has worked perfect. It also factors in tire pressures or tire squat.

Kevin

 

[NoSeeUm]

I did all the math, then used the GPS. It was still off. But I eventually got mine pretty close via trial and error.



Like Bob says I could not get GPS accuracy out of the speedo indication. I found that I could only get close enough for a good compromise.



I am currently using stock sw. On thing that I did notice, that must be some what of a Dodge quirk, is that speedo error is non linear. By that I mean, for example with my 285's the speedo is off by right at 3 mph at 30 mph and 60 mph. In fact it is 3 mph low at just about any mph. For my mpg correction I use 1. 06 but that is not 100% correct.



Example:

@ 30 mph indicated the error = 1. 11

@ 60 mph indicated the error = 1. 05



So in my case I sort of fudge up a weighted average and use 1. 06 based on the speeds I travel at mostly.



Jim