FORScan Tire Size Adjustment For 37 Inch Tires

[BuiltPowerStrokeTough]

Originally Posted by Sleepersilverado

Hopefully mine don’t rub with the 3 link.

I think what shef was saying is to run the tire size up to the max in the computer then trick the truck by changing the gear ratio in the computer. Simple online calculator says from factory tire to 37 would need to change back to a 3.85 gear ratio. Shows effective ratio of 3.27 with new tires.

Oh, I misunderstood. I thought he was saying about the spreadsheet to calculate the new tire size values in FORScan. Didnt know there was a setting for the gear ratio too.

Originally Posted by Shef

Correct. I think they said and don't quote me but for 37s you would enter 3.20. That's how they got rid of the check engine light. Not sure if they adjusted the tire size. I inquired about reprogramming at Sawgrass Ford in Sunrise FL the other day. They sell several Super Duties lifted with 38s. Their accessories department guy said the service department can reprogram mine when I get the 37s put on.

If you could when you get the new tires put on, let me know what process they used when they program for the 37s, if the speedo is accurate and if its successful without any lights. If the Ford dealer can actually do that, then I may look into that route as well.

[Shef]

Will do, just waiting on the Fox resis to show up. Doing the BDS 4" radius arm lift with SOTA 22X10.5 Novakanes and 13.5s if they'll fit if not 12.5 Ridge Grapplers.

[BuiltPowerStrokeTough]

Originally Posted by Shef

Will do, just waiting on the Fox resis to show up. Doing the BDS 4" radius arm lift with SOTA 22X10.5 Novakanes and 13.5s if they'll fit if not 12.5 Ridge Grapplers.

I have a buddy who works at a local Ford dealer who has access to Fords IDS. He said he would hook to it to see what how big of a tire I could put in through their system. However, I was talking with Jared Rice last night about it as well, and he mentioned that IDS can only adjust to 34.6" tires. So I dont know how that other dealer is adjusting it, but it must not be IDS. Would be interested to find out what they are using to adjust it. Maybe you could call them and they could volunteer that information up. But so far, looking like Ill have to buy that Hypertech module to get it to 37s.

[vr6dub]

Originally Posted by Shef

Will do, just waiting on the Fox resis to show up. Doing the BDS 4" radius arm lift with SOTA 22X10.5 Novakanes and 13.5s if they'll fit if not 12.5 Ridge Grapplers.

Shef,

I have this same set-up with 37/13.5 Toyo MTs and it rubs when turning on the backside of the front fenders. Going to drop to 12.5's when i burn through these tires to see if that makes rubbing a lil less.

[Shef]

vr6, Thanks for the info. Can you post a pic of where it rubs? Black plastic piece at bottom rear of fender?

Thanks

[vr6dub]

Shef,

Exactly where it rubs on mine. I trimmed it until i seen metal and stopped and that helped quite a bit, but it tills rubs pulling into my driveway or any type of bump while turning. I'll get some pictures posted up of the area in a little. I also have bushwacker flares on it so the black trim is covered but i've trimmed the heck out of those in the same areas and it's not the flare getting hit.

[BuiltPowerStrokeTough]

Well, I may have found a set of numbers to use in FORScan for the 37s that maybe wont throw a check engine light. I will update this afternoon after I get a chance to throw the numbers in to double check if theres a light and how close it is at 70 mph. Hopefully this will get the job done so I dont have to buy the hypertech.

[Joseph_the_builder]

Did you get the chance to check the new numbers for the FORScan that won't throw a check engine light?

[BuiltPowerStrokeTough]

Originally Posted by Joseph_the_builder

Did you get the chance to check the new numbers for the FORScan that won't throw a check engine light?

No not yet unfortunately. I was supposed to try it all out before I went out of town last weekend, but had too many things to do before I left that I didnt get a chance. I will hopefully give it a try within the next couple days and report back. Have you tried any adjustments yet on yours with FORScan? Results?

[BuiltPowerStrokeTough]

Well, I just adjusted my tire size in FORScan last night. Also turned bambi mode on (fog lights stay on when the brights are turned on). Changed in the BdyCM module from 726-12-01 xxxx 0A00 xxxx factory settting to 726-12-01 xxxx 0AAE xxxx. Drove it for 40 miles and no check engine lights. Also, at 70 MPH on the speedometer, my GPS shows Im at 71-72 mph. It bounces back and forth between the two. So I am within 1-2 mph low on the speedo compared to GPS. I am MORE than happy with that amount. Hell when I was stock if I recall I was 1 MPH off still. When I was at lower speeds like 40mph, I was right on the money. I am just happy I am no longer 7 mph off and dont have to go out and buy that HyperTech module. So for those that are running 37x12.50R18 Nitto Ridge Grapplers, 0AAE code seems to be almost spot on. Other tire brands/models may be a little different, but I doubt it would be that much different. Ill continue to drive it and see if I get a light, but I doubt one will ever come on if it hasnt in 40 miles or mixed driving.