40-Inch Tire Discussion (Or anything bigger than 37's)

[OffroadTreks]

Wanted to start a separate thread to discuss details pertaining to moving to 40-inch tires on both 3rd & 4th gen Power Wagons. Kind of a one source thread.

I know a few 3rd gen guys already managed. And there have been a small number of shop built 4th gen Power Wagons already out with 40's, usually running weird hybrid lifts. (click here to see video of 2017)

So, there are a few ways to run 40's. Some more half-assed than others....



But this thread won't discriminate. One thing we will discuss, there is no actual need to use AEV's lift kit. They are not the only method of doing 40's, unless we are talking about using their flares.

I plan on moving to 40's at some point for PWIM 2019. But I just wanted to start this thread as an idea thread and research thread for anyone esle following or in the process. I think Reloader mentioned he wants to move up too.

I don't have all my thoughts gathered but wanted to start the thread anyhow. Let's begin.

[OffroadTreks]

Gear Change Notes

The front R&P in your trucks is the same as:
14+ 2500
13+ 3500
https://www.ringpinion.com/b2c/ProductD ... howAA=true

Randy's isn't the only game in town.
https://eastcoastgearsupply.com/c-96234 ... nions.html

Thanks. Just got off the phone with EastCoast. They were great, very knowledgeable and by far the best prices for Yukon gears I've found.
$1350 + Tax (free shipping) should put most of us under $1,500.
Nitro Gear Kit (NG-GPRAM-4.88) runs about the same, maybe $100 cheaper.

East Coast gear supply supplied my AAM 4.88 Rear 3 years ago. I posted my receipt if you search with every part number that will be required including that newer seal that these rear axles require.

Complete Gear change kit PN# NG-GPRAM-4.88

Kit included the following;

Nitro 4,88 R&P Rear PN# AAM 11.5-488-NG
Nitro 4.88 R&P Front PN# GM 9.25-488R-NG

Nitro Master install Kit Rear PN# MKAAM11.8-B  
(Note this kit will include the conversion bearing required to run the aftermarket gears in the new housings)

Nitro Master install kit Front PN# MKAAM9.25
The bearing install kits included new crush sleeves, pinion shims and pinion nuts as well as gear marking compound/brush and a small pouch of assembly lube

Alternate options for the bearings from Yukon Gear are as follows, both of these kits contain the conversion bearing also;
Master install kit Rear PN# YK AAM 11.5-CONV (Complete bearing and seal kit for the 14+ housings)
Pinion only bearing kit Rear PN# PK AAM 11.5_CONV
(Pinion seal and inner/outer bearings only)
If you want to buy the front conversion bearing by itself the Timken part numbers are;
Bearing HM807035
Race/cup HM807010

Misc fluids/chemicals
8 qts of synthetic gear oil. (I chose Royal Purple) Book says 7.2 qts to fully service both differentials.
Brake clean for cleaning the housing and part and to remove the shipping/storage coating (cosmoline) from the new gears.
A good quality silicone sealant for the axle shafts when reassembling. (A thin layer is sufficient to allow the original gaskets to seal) If gaskets tear or are in bad shape replace them.
White Lithium Grease

[Reloaderguy]

Little 40's or big 40's?

I've said I don't want 40's enough times to know that I'm doing 40's. The turning point was Damage Wagon talking me into hydro. I was planning late summer or early fall for 38's but if I'm going to do this it'll be the beginning of next year before it happens. I'm leaning towards AEV flares.

[olyelr]

Dont be silly, you know 40’s can not be done without the AEV suspension system. Quit hating











In reality, “fitting” 40’s on a 4th gen ram is going to require one of 3 things that I am aware of;

1. Removal of a large portion of the fenders.

2. Skyhigh lift with wicked large bump-stops.

3. AEV flares along with roughly a 2+” lift.

Since Thuren or Carli coils are quite popular and put the truck essentially very close to the same heigt as an AEV lifted Ram, it would seem that adding the AEV flares in conjunction with these springs would offer enough clearance. Pushing the axle forward a bit may still be a requirement (DOR long arm kit?). And even with the flares, some added bump-stop may still be needed as well.

And then, of course, would be the much needed upgrades to steering, brakes, gearing/drivetrain etc.

[DamageWagon]

Fiberglass fenders is an expensive, painful, sweet mod versus AEV flares.

Lift has nothing to do with fitting bigger tires unless you’re talking a HUGE lift and bump drops. A 2” Lift doesn’t change anything because you’re hitting bump at the same place.

[TommyG]

Fiberglass fenders is an expensive, painful, sweet mod versus AEV flares.

I've been thinking this would be the way to fly with a control arm suspension since we can't move the axle ahead as much. Not crazy about the way the Fiberwerx fenders look but they would do the trick. Any other vendors you have looked at?

[olyelr]

Fiberglass fenders is an expensive, painful, sweet mod versus AEV flares.

Lift has nothing to do with fitting bigger tires unless you’re talking a HUGE lift and bump drops. A 2” Lift doesn’t change anything because you’re hitting bump at the same place.

True. Thats why I mentioned added bump-stops may still be needed. I suppose the lift wouldnt be required if you wanted to ride on bump-stops.

[Bill2014]

Per Thuren:
(For the latest gen PowerWagon)

Lift height, under 4" of lift, does nothing for tire clearance.

The truck will clear the same tires and wheels stock height, as it does with 3" of lift.

[Reloaderguy]

Fiberglass fenders is an expensive, painful, sweet mod versus AEV flares.

Lift has nothing to do with fitting bigger tires unless you’re talking a HUGE lift and bump drops. A 2” Lift doesn’t change anything because you’re hitting bump at the same place.

True. Thats why I mentioned added bump-stops may still be needed. I suppose the lift wouldnt be required if you wanted to ride on bump-stops.

You'll need a 1" bumpstop drop. 38's are the largest tire that will fit without needing extended stops.

Fiberglass fenders are a huge pain in the ass and they may provide less clearance than the AEV flares.

ETA: Fiberglass fenders/bedsides aren't an option for Ram Box beds.

[OffroadTreks]

As for big or little 40, I guess I should say, everything over 37. Becuase I've looked at BFG Krawlerz which are 39-inches but come in at 38.50. I'm personally staying in around 13.50 wide. No 15 wide tires for me. It would be awesome if SOMEONE, ANYONE made a tall and skinny. But that doesn't seem to be a reality right now.

---

Fiberglass just isn't ideal. Unless you're having the work done professionally. Aftermarket options are all widebody for Baja/PreRunner from what I've seen. I'm not going for that. That leaves AEV's flares as the best readily available option. There might be another option, as some have had luck fitting other aftermarket large pocket flares, but I don't want to experiment that much in that area personally.

---

I'll be doing this using my current Thuren setup. As DamageWagon already said, lift does nothing for tire clearance up to a point. I want to maintain a LOW center of gravity. And not go beyond were I am at now.

Since Thuren or Carli coils are quite popular and put the truck essentially very close to the same heigt as an AEV lifted Ram, it would seem that adding the AEV flares in conjunction with these springs would offer enough clearance. Pushing the axle forward a bit may still be a requirement (DOR long arm kit?). And even with the flares, some added bump-stop may still be needed as well.

I'm technically sitting higher than AEV's lift kit right now. That is the big WHY talking point I use for anyone with a PW who even considers the AEV lift. You are literally getting a level out of your PW. The rear is the same height. The front is the same height as Thuren's 1.5 coils. Since I have a rear spacer, my rear is even taller. It's a lot of money to waste for a level, not to mention all the other things going on in that kit. But I'll leave that for the other thread.

I understand the basic principles of the suspension traveling in an arc as it drops, I'm just not very good at explaining it. So the axle forward deal, I'm not 100% sure about. Reloader might be right about not needing the spacer and moving a 1/2 inch. There is some debate even about using the drop brackets and whether or not that is really necessary. (Most likely, this is certainly necessary for 40's, but in a discussion about 37s....)

All of us radius arm guys with Thuren's kit, don't have drop brackets on our radius arms. Is our suspension worse off than compared to a carli lift or AEV's with the drop bracket???

We are going to travel this summer, and in the fall (Oct or Nov) I'm going to rear gear. I think, but I'm not convinced yet, I will be upgrading the front axle to a Dyntrac free-spin kit. Most likely I will be adding hydro as well, possibly all around the same time as the re-gear.

[OffroadTreks]

DamageWagon's rear bumper plans though might delay my move to the 40's. If he comes up with a design within the year (cough, cough) I'll be allocating money to that before 40's.

I also need to buy the wife a vehicle, we're seriously thinking about a 2019 Ram Rebel now. Just has never been a priority since we both work from home.

[Colibri]

The only reason Carli uses drop brackets on the radius arm trucks is they are running a taller front coil than Thuren does.

[Reloaderguy]

As for big or little 40, I guess I should say, everything over 37. Becuase I've looked at BFG Krawlerz which are 39-inches but come in at 38.50. I'm personally staying in around 13.50 wide. No 15 wide tires for me. It would be awesome if SOMEONE, ANYONE made a tall and skinny. But that doesn't seem to be a reality right now.

---

Fiberglass just isn't ideal. Unless you're having the work done professionally. Aftermarket options are all widebody for Baja/PreRunner from what I've seen. I'm not going for that. That leaves AEV's flares as the best readily available option. There might be another option, as some have had luck fitting other aftermarket large pocket flares, but I don't want to experiment that much in that area personally.

---

I'll be doing this using my current Thuren setup. As DamageWagon already said, lift does nothing for tire clearance up to a point. I want to maintain a LOW center of gravity. And not go beyond were I am at now.

Since Thuren or Carli coils are quite popular and put the truck essentially very close to the same heigt as an AEV lifted Ram, it would seem that adding the AEV flares in conjunction with these springs would offer enough clearance. Pushing the axle forward a bit may still be a requirement (DOR long arm kit?). And even with the flares, some added bump-stop may still be needed as well.

I'm technically sitting higher than AEV's lift kit right now. That is the big WHY talking point I use for anyone with a PW who even considers the AEV lift. You are literally getting a level out of your PW. The rear is the same height. The front is the same height as Thuren's 1.5 coils. Since I have a rear spacer, my rear is even taller. It's a lot of money to waste for a level, not to mention all the other things going on in that kit. But I'll leave that for the other thread.

I understand the basic principles of the suspension traveling in an arc as it drops, I'm just not very good at explaining it. So the axle forward deal, I'm not 100% sure about. Reloader might be right about not needing the spacer and moving a 1/2 inch. There is some debate even about using the drop brackets and whether or not that is really necessary. (Most likely, this is certainly necessary for 40's, but in a discussion about 37s....)

All of us radius arm guys with Thuren's kit, don't have drop brackets on our radius arms. Is our suspension worse off than compared to a carli lift or AEV's with the drop bracket???

We are going to travel this summer, and in the fall (Oct or Nov) I'm going to rear gear. I think, but I'm not convinced yet, I will be upgrading the front axle to a Dyntrac free-spin kit. Most likely I will be adding hydro as well, possibly all around the same time as the re-gear.

I'm not sure how close you've looked at 40's but most of them for 17" wheels are C rated. I've been mainly looking at 20" wheels because of how soft the tires for 17's are. 20's are seriously expensive though. 40x15.5R20 and 20" beadlocks are deep into the $5K range (for four each). 40x13.5R17 and corresponding beadlocks are closer to $4K. Unfortunately PW stock wheels have waaaaaay too much backspacing.

[Easttnrhino]

Hate to get off topic but whos blue wagon is that in mike keys post and any idea what brand of bumpers.thanks and sorry.

[Bill2014]

.. Unfortunately PW stock wheels have waaaaaay too much backspacing.

The stock PW wheels aren’t even big enough for most of the 35’s and 37’s out there - but that doesn’t stop people from using them anyway.

[Reloaderguy]

.. Unfortunately PW stock wheels have waaaaaay too much backspacing.

The stock PW wheels aren’t even big enough for most of the 35’s and 37’s out there - but that doesn’t stop people from using them anyway.

Well yeah but they're forged and round so some people think they're made from unicorn semen.

[adeluca73]

Although cool looking, I can’t help but question the necessity of a 40” tire. Is a 3” nominal diameter gain & and 1.5” clearance gain worth the hassel, $, and extra mods required to run 40’s? Given an exemplar 40x15.5x20 from Toyo or Nitto, the unsprung weight increases over 100% over the stock Duratracs (200 vs 440 lbs) & about 50% over my 37” Nittos. Plotting a simplifed time history response to a generalized sinusoidal input force to a 2-DOF approximation of the system (shocks/springs/tires+ nominal other mass) using Theuren’s springs (K=390ft-lbs/in) which is about 40% less stiff than OEM springs & King 2.5’s on stage 4, you will get a dramatic increase in time history decay, which makes drivers response longer and undesirable. Further the stress on driveline components & the increased rolling MOI will accelerate brake system wear, decrease brake fluid efficacy, decrease accelerator & brake responsiveness, and will most certainly require 4.88’s or 5.13’s. But hey it’s only $, right!

[DamageWagon]

Although cool looking, I can’t help but question the necessity of a 40” tire. Is a 3” nominal diameter gain & and 1.5” clearance gain worth the hassel, $, and extra mods required to run 40’s? Given an exemplar 40x15.5x20 from Toyo or Nitto, the unsprung weight increases over 100% over the stock Duratracs (200 vs 440 lbs) & about 50% over my 37” Nittos. Plotting a simplifed time history response to a generalized sinusoidal input force to a 2-DOF approximation of the system (shocks/springs/tires+ nominal other mass) using Theuren’s springs (K=390ft-lbs/in) which is about 40% less stiff than OEM springs & King 2.5’s on stage 4, you will get a dramatic increase in time history decay, which makes drivers response longer and undesirable. Further the stress on driveline components & the increased rolling MOI will accelerate brake system wear, decrease brake fluid efficacy, decrease accelerator & brake responsiveness, and will most certainly require 4.88’s or 5.13’s. But hey it’s only $, right!

Yeah sure, but... 40’s!

It’s like owning a 1st gen cummins, old land cruiser, old Jeep - they’re super cool! Until you’re the dude owning it and it’s a constant list of bullshit just to get it to the grocery store under it’s own power without the frame rot finally letting the whole thing snap in half. The list of problems increases exponentially while the capability also decreases. But hey, 40’s look good and you can stop picking good lines Offroad and just bulldoze, so...

[Chromolykid]

Quite a few Trophy Truck teams tried 42” race tires, went back to 39’s after a couple races, just sayin’... Accelerated wear and added mass like adeluca mentioned, even multi-million dollar teams came to the conclusion that bigger isn’t always better.

[Reloaderguy]

Double

[Reloaderguy]

Although cool looking, I can’t help but question the necessity of a 40” tire. Is a 3” nominal diameter gain & and 1.5” clearance gain worth the hassel, $, and extra mods required to run 40’s? Given an exemplar 40x15.5x20 from Toyo or Nitto, the unsprung weight increases over 100% over the stock Duratracs (200 vs 440 lbs) & about 50% over my 37” Nittos. Plotting a simplifed time history response to a generalized sinusoidal input force to a 2-DOF approximation of the system (shocks/springs/tires+ nominal other mass) using Theuren’s springs (K=390ft-lbs/in) which is about 40% less stiff than OEM springs & King 2.5’s on stage 4, you will get a dramatic increase in time history decay, which makes drivers response longer and undesirable. Further the stress on driveline components & the increased rolling MOI will accelerate brake system wear, decrease brake fluid efficacy, decrease accelerator & brake responsiveness, and will most certainly require 4.88’s or 5.13’s. But hey it’s only $, right!

You forgot depreciation, but yes to all of it. No one said it was logical or a good idea.

[Reloaderguy]

Quite a few Trophy Truck teams tried 42” race tires, went back to 39’s after a couple races, just sayin’... Accelerated wear and added mass like adeluca mentioned, even multi-million dollar teams came to the conclusion that bigger isn’t always better.

KOH U4 didn't go back to 39's though.

[OffroadTreks]

We’re not building Wagons to drive around DC and kiss the mall parking lot either.

The C rating doesn’t bother me for not towing. Load index is enough for the rig. For the axle it’s 6,390lbs.

Is a 3” nominal diameter gain & and 1.5” clearance gain worth the hassel

Yes.

As DamageWagon said, the real answer is Bulldoze. As someone who has tested a few setups, the step up from 33 to 35 was not nearly as noticeable offroad as 35 to 37's. I tested on the same trails in Moab, that small difference between the two tires was huge offroad. That nominal difference on the 40's should also be an advantage.

[OffroadTreks]

You forgot depreciation, but yes to all of it. No one said it was logical or a good idea.

Only accountants are sitting around worrying about depreciation on a liability anyhow. It’s not an asset.

How much was already thrown down the drain on mods no one else will give a shit about??

[Reloaderguy]

You forgot depreciation, but yes to all of it. No one said it was logical or a good idea.

Only accountants are sitting around worrying about depreciation on a liability anyhow. It’s not an asset.

How much was already thrown down the drain on mods no one else will give a shit about??

Loans are liabilities. Assuming you're not a corporation using your PW for business, it is an asset. It's asset value is determined by the market price when disposed of or sold (or assessed by a court, government agency, or financial institution). Since your asset is declining in value over time, it is a depreciating asset. 40's (modifications) accelerate the depreciation but depending on how long you keep the truck, the actual amount of depreciation (assuming the modifications don't add value to prospective buyers) can vary.

Maybe we should call it an "investment in our happiness"? That's immeasurable after all.