Upgrading to 35’s

[Lazarus]

I am upgrading to 35’s this week and am wondering if I will be able to have four wheel parts (where I’m buying the tires) or the dealership change the speedometer programming for my truck after the bigger tires are on there. It’s a 2018 (built December 2017), and I thought I read something about needing a bypass module to make any changes like that, but I just wanted to confirm. I don’t really care about the tire pressure sensors, but it would be nice to change the parameters on that as well. Also, for anyone who has upgraded to 35’s, did you change any of the transmission shift points or programming? If so, which tuner do you recommend? I’d like to just put the 35’s on there and not worry about any of this, but I’m not sure how it’s going to affect the drivability of the truck. I’m very new to all this computer stuff with my truck so any info you could pass along to me would help greatly.

[Punishher7]

There are several available now but the AEV procal I bought came with the bypass cable. You need it IOT change any settings through the OBD on 2018+ models IIRC. I went further and reprogrammed the TPMS but it’s not needed. The AEV makes it shift right again.


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[KevinABQ]

At the very least your speedometer will be off without reprogramming. Apparently the dealers can't fix TPMS, so you need one of several tools for that. I used Alfaobd, but tire size changes their are a little complex in it, and if you don't do it right you'll know it. TPMS is easy and it's very flexible.

[Lazarus]

After doing more research, I’m leaning towards the procal. It seems like it does everything I need it to without having to dig into my dash and install that bypass module. Did you have to install the bypass to use alfaobd?

[pdavey]

I am using the Tazer Ram by Zautomotive. They have a bunch of other functions as well. Very happy with it so far.

You will need a bypass module unless you have a classic or tradesman model. It is located behind the 8.4 Uconnect radio on the 2018s.

I went with 35x12.5 Nitto Ridge Grapplers on stock rims. Very happy with them so far.

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[KevinABQ]

After doing more research, I’m leaning towards the procal. It seems like it does everything I need it to without having to dig into my dash and install that bypass module. Did you have to install the bypass to use alfaobd?

Yes. On an 18 it’s behind the radio. In theory there is a cable that allows it to be plugged into the odb2 port, but the cable I have is trash. It has no instructions and seems to want to connect to a terminal block that isn’t there. There are others that seem much better based onreviews. But without replacing the security module you can’t address the radio. Truthfully there isn’t that much that you can program on the radio, which is why I tried the cable.

[a55]

Truck: Stock 2018 Power Wagon

Decided to buy Toyo Open Country M/T 35s myself, found four for just under $1200 out the door, I am new to the Power Wagon thing, not entirely new to offroading, but definitely more of a casual, than even an enthusiast. Shop says they can reset the TPMS and tell the truck's computer it has these tires on it now.

Sounds like I don't need to do any Procal work myself?

What else do I need to look out for, what pressure should I set if I am probably going to be doing 50% highway mall crawling grocery getting out to dinner, and gravel and the rest not really rock crawling offroad? So I guess what is a good, get you to the dirt, pressure? This is not my daily driver. I've had it for a few months, and still have less than 1000 miles on it.

Thank you, and I don't mean to hijack OPs thread.

[Rodeoflyer]

Set them to 45 front/40 rear depending on your shocks. Good starting point then adjust up or down for comfort level.

Offroad down to 20psi depending on terrain (rock/sand/mud).

Rotate them often, like every 3k miles often.


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[pdavey]

If you want to have custom set points for your tires the dealer has to flash something after the change in the tuner. I just disabled TPMS.

With 35s if you can't tell when to pull over you may need to learn to drive

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[Lazarus]

I had the dealer try to convince me today that the only way I can get the procal to work is to purchase through them and have them perform the work to the tune of $350. He said a special “flash” is needed for the truck to accept any of the changes, including changing the tire size and changing my fogs to run with hi beams. Seems to me like it is something I can easily do myself in the driveway.

[Lazarus]

Can I just turn off tpms with the procal?

[Jack187]

I think this will probably help quite a few people out to reset their Gen 4 TPMS threshold.

Once my new Powerwagon arrived, I compiled all the information I had seen posted in various posts into one list of steps and took my truck to my dealership to get my TPMS threshold lowered.

They initially ran into a TPMS flashing issue after they had stored the new requested value into the computer. The tech came out to me and said the updates had been applied, but the system was still flashing. I gave him the steps I compiled below and he came back 20 minutes later saying it was all working. I can confirm my thresholds were lowered from 65 PSI to 50 PSI and I am running 50 PSI in the tires currently with no warnings. My tire pressure now has to drop below 40 PSI before TPMS warning will show in the console. Below is a list of the steps I gave him. I hope this helps anyone still experiencing this issue.

TPMS Minimum Threshold Adjustment steps:

1. If the low tire pressure indicator has already been triggered, all tires should be inflated back to the default 65 PSI (PowerWagon default pressure) prior to adjusting the pressure threshold in the vehicle’s computer system. Once it is verified there is no low pressure warning in the console after starting the vehicle, proceed to step 2.

2. Enter the low tire pressure threshold in the body control module BCM to desired air pressure
(50 PSI was desired in my case but you can go lower) (65 PSI is standard).

3. Run the function in the Radio Frequency Hub RFH, "RFH replace" (not actually replacing it).
When run, this function will transfer the desired air pressure thresholds from the BCM to the RFH.

4. Lower the pressure in the tires one at a time (rear tires first) to desired pressure PSI (50 PSI for mine). Check for triggering of the low tire pressure warning on the cluster after lowering each tire. If the warning triggers after any tire is lowered to the desired pressure (50 PSI in my case), the update to the computer failed. In case of a triggering of the warning, all tires must be re-inflated to 65 PSI and the process must begin again at step #1.

Under the factory setting of 65 PSI, the low tire pressure indicator will activate if any tire goes below 52 PSI (which is 80% of the threshold).
The built in logic allows a 20% variance from the stored value. So, for example, if the new desired pressure of 50 PSI is used, the low tire indicator should not trigger until the pressure reaches 40 PSI.

I found a second post recently from another guy (apparently also a tech) that did not include the pressure resetting steps. I am including it below.

"Ok guys.... I've done this on several trucks now and have confirmed it will work on any 2014+ and on any model (I have not tried it on C&C yet). You will have to have this done at a dealer. Print this and take it in and they should be able to change your settings and turn off the light. It takes about 10 minutes.

Step 1: Go into the BCM (body control module). Go to "miscellaneous functions". Go to "update pressure thresholds". Set pressure to desired settings. Do not try to do different pressures front and back! Even if you run 10 psi difference front to back you won't get a light. If you plan to run 10 psi difference I suggest your "setting" be in the middle of the high and low just to give you a little cushion.

Step 2: Go into the RFH (radio frequency hub). Go to "miscellaneous functions". Perform "RFH replace" and follow prompts. You will need the PIN number for the truck. That can be obtained through Dealer Connect with the vin number to the truck. When following the prompts - when asked for desired pressure setting - set new pressure levels. You do not need to replace anything - just perform the function to set new levels.

I have not had to drive the truck - once the RFH replace function is done the light goes out and the truck is reading new pressures.

Done!!"

[cb1987]

tpms warning lights get annoying very fast. i reset my pressures to 40psi with a autel that i rented from a guy on one of the ram forums. seems like he charged about $100 but dont quote me. was a 10min job. havent yet recalibrated the speedo for the larger tires, not sure when or if i ever will, got ten million other things on my plate right now. havent bothered with any tranny shift points changes, drives fine as is but i dont tow anything either

[PWJouster]

The Autel rental is positively the best way to get this done, if your so inclined to read directions.

It was easy once you get the Code for your truck from the dealer...which clearly, is market and dealer dependent.

[cb1987]

ive never used a scanner in my life and it still only took me about 10min with the autel. even a monkey could do it. getting the pin was easy for me. went in the dealer with truck registration and driver liscense. less than 10min i was out the door with the pin

[Reloaderguy]

The Autel is obsolete. Instead of renting one just buy AlfaOBD and OBD MX. During my last warranty episode the dealer reflashed my BCM. I had to redo all of the changes I previously did. There's no sense renting the Autel if you're just going to have to rent it again.

[cb1987]

autel isnt obsolete and works just as well as anything else for resetting tpms. but ya , renting one doesnt make sense if your going to the dealer every week and have to keep changing the tpms

[Lazarus]

Anyone with 35s know if the larger spare stuffed under the bed interferes with the rear track bar? I had to deflate and re inflate to get it up there. It seems like there’s just enough room for the track bar to not hit it but if I got into a major flex situation it might. Anyone had experience with this?

[TankerZak]

Lots of people. It's fine. Guys went to Moab many times with a 35 stuffed up there and flexed the shit out of the truck. No issue.

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[TankerZak]

I did the Autel Rental the first time. One if the recalls undid everything. Had to buy a Procal to reset it again. But what it didn't undo was the dealer reset of the BCM that needed to be done BUT AlphaOBD can maybe do that? Not sure, haven't checked.

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[Reloaderguy]

autel isnt obsolete and works just as well as anything else for resetting tpms. but ya , renting one doesnt make sense if your going to the dealer every week and have to keep changing the tpms

I've used the Autel MaxSys multiple times and it lacks most of the functionality of AlfaOBD. I don't even have TPMS set up anymore, I switched to TPIS because Autel can only lower the TPMS threshold to 28PSI. I have also activated AUX switches, edit the LFW threshold, etc. The Autel is obsolete, if you want to pay to rent one that's your call but you can buy a clearly superior system for the same money and use it on any FCA vehicle any time you want...forever. It fits in your pocket too.

[Rodeoflyer]

I’m about to buy the OBD mx Bluetooth and alpha obd. This is the first thing I’ve seen that I’d spend my money on. Thanks for posting this info!


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