Ford ProCal will adjust speedometer for new tire sizes.

[tehschkott]

Pleasantly surprised to learn the Ford ProCal tool purchased with my ECU tune will adjust speedometer for new tire sizes, too. You have to calculate rotations-per-mile yourself, but mfg post that stat if you know to look for it. Hooray for accurate speedometer again.

Edit: Posting up here so you don't have to dig through the thread.

The Ford ProCal is going to ask you to set the revolutions per mile - I just googled my tire in my size and I think it was 657 - this is a much lower number than it was reading stock (691) but that makes sense since my newer tires were bigger ; bigger tires will require fewer revolutions per mile. Plugged that in, followed the instructions, took it for a test drive.

I use Waze as my traffic app and it has satellite fed mph speed that's very accurate - when Waze says I'm doing 70, it's 100% on. So I test drive the truck looking at the speedometer vs Waze on the highway; set the cruise control at 60 (or whatever, higher the better) and pay attention to the two.

In my case I was now under-reporting; the jump from 691 to 657 was too great. So I pulled off the exit, adjusted the numbers up (by 10) to 667 and gave it another test drive. Closer but still under reporting. Pulled off the exit, adjusted it up by another 5 to 672 and everything lined up.

Everyone is going to be a little different depending on tire/wheel collabo so don't use my numbers. For example: Grapplers are going to measure slightly different than KO2 even if they say they're the same size. And The same tire on different rim widths is also going change that profile some too. So everyone is a little different. Understanding the process is the more important part of all this. Once you have that down... its cake. When next you get winter tires put on (or get different sized tires) you now know how to calibrate your speedo so they line up. Note the old number so when you take your winter tires off again and put your summer tires back on, you can plug your old numbers back in. As long as they're the same tire on the same rim, the numbers will hold.

Sponsored

 

[Johnv1991]

Pleasantly surprised to learn the Ford ProCal tool purchased with my ECU tune will adjust speedometer for new tire sizes, too. You have to calculate rotations-per-mile yourself, but mfg post that stat if you know to look for it. Hooray for accurate speedometer again.

How do you find the tune?

 

[tehschkott]

Very mild. But a big and welcome improvement in shift schedule.

 

[Goodrx]

Is it the Ford performance tune that comes with that warranty?

 

[tehschkott]

Is it the Ford performance tune that comes with that warranty?

yes

 

[Goodrx]

yes

So it’s very mild tune with very minimal noticing? Did it improve gas mileage at all or just make it more accurate for the computer to calculate?

 

[ajohnson]

My Pro Cal device refuses to read the correct speed. Double checked my rev/mile and gear ratio in the ProCal device. Had my Ford dealer look at it too. They verified the truck is sending the right signals and could not find anything wrong with it. Talked to FP and they said it's a known issue but did not offer a fix.

 

[tehschkott]

So it’s very mild tune with very minimal noticing? Did it improve gas mileage at all or just make it more accurate for the computer to calculate?

It's a mild tune and I don't notice a super big change in motor improvement, but shift schedules are greatly improved and gas milage is improved. It's a series of small improvements that, together, yield a welcome improvement in overall experience.

And you can set your tire size with it. I don't ask it to read the correct size, I tell it what size to use. Are you saying entering a new size won't stick?

 

[Goodrx]

It's a mild tune and I don't notice a super big change in motor improvement, but shift schedules are greatly improved and gas milage is improved. It's a series of small improvements that, together, yield a welcome improvement in overall experience.

And you can set your tire size with it. I don't ask it to read the correct size, I tell it what size to use. Are you saying entering a new size won't stick?

I don’t have a device I’m at a crossroad between Ford and livernois. Only reason and I mean only reason for Ford is for the warranty protection.

 

[tehschkott]

I don’t have a device I’m at a crossroad between Ford and livernois. Only reason and I mean only reason for Ford is for the warranty protection.

Ah. Well I like it. Maybe after my warranty expires I'll do the Livernois.

 

[Shomare]

Any tips on doing the calculation. I have the same tune and calibrator and will need to adjust when I go to 17 wheels and taller tires. I have the BAP with 18 in wheels now

 

[Krzydmnd]

this should tell you what you need to know...

https://tiresize.com/comparison/

 

[tehschkott]

its going to ask you to set the revolutions per mile - I just googled my tire in my size and I think it was 657 - this is a much lower number than it was reading stock (691) but that makes sense since my newer tires were bigger ; bigger tires will require fewer revolutions per mile. Plugged that in, followed the instructions, took it for a test drive.

I use Waze as my traffic app and it has satellite fed mph speed that's very accurate - when Waze says I'm doing 70, it's 100% on. So I test drive the truck looking at the speedometer vs Waze on the highway; set the cruise control at 60 (or whatever, higher the better) and pay attention to the two.

In my case I was now under-reporting; the jump from 691 to 657 was too great. So I pulled off the exit, adjusted the numbers up (by 10) to 667 and gave it another test drive. Closer but still under reporting. Pulled off the exit, adjusted it up by another 5 to 672 and everything lined up.

Everyone is going to be a little different depending on tire/wheel collabo so don't use my numbers. For example: Grapplers are going to measure slightly different than KO2 even if they say they're the same size. And The same tire on different rim widths is also going change that profile some too. So everyone is a little different. Understanding the process is more important than pulling the numbers. Once you have that down... its cake. When next you get winter tires put on, you now know how to adjust your speedo so they line up. Note the old number so when you take your winter tires off again you can plug your old numbers back in.

 

[tehschkott]

How do you find the tune?

You know what, I have to update my thoughts here.

I re-flashed my ECu today and saw an immediate, very large improvement in HP and torque and gas milage.

I feel like the first time, I only got the improved shift schedule, not the HP/torque improvements. This second time, I got the whole thing. The tune is very good and very notable.

 

[Johnv1991]

You know what, I have to update my thoughts here.

I re-flashed my ECu today and saw an immediate, very large improvement in HP and torque and gas milage.

I feel like the first time, I only got the improved shift schedule, not the HP/torque improvements. This second time, I got the whole thing. The tune is very good and very notable.

Interesting. Thanks for the update. What made you go with FP vs Livernois? Just curious

Sponsored