Tire sizes vs. axles

[sirhk100]

Hey guys, curious your thoughts. My old '92 I ran open front and rear with cut and turned beams and extended axles on 33's with no issues ever once I got rid of the stock auto hubs and put on some manuals.

My current '91 is sitting on 35's open front and rear but I haven't even touched dirt with it because I just finally got some custom wider axles machined and my 3rd is being regeared to match the rear. The thing is though, my current '91 is a basket case mechanically and I've decided to pickup a complete stock expo in good shape to swap my goodies over to.

So this weekend I'm possibly picking up another '91 to swap all my goodies onto and then I'm going to scrap what's left. This one I might be picking up has a powertrax noslip up front. Basically with the parts I have on hand the front axle will still be stock 35 3rd with a powertrax, 4.56 and custom machined extended axles because my beams are widened.

The expo will be my daily driver and used for mild crawling. I know the obvious answer here but... I have the option of running 35's or 33's. I'm right now leaning towards 33's for reasons other then what I'm about to ask but...

For mild crawling, are 35's going to be a sure axle snapper up front with the locker? What's the typical weak link in the front end when going to bigger tires? The axles I had custom machined are a heat treated 300M material so I'm pretty confident they won't be the weak link. I'm kinda hoping the stock axles are what typically snaps cause if so, maybe I'll be fine even if I decided to stick with 35's.

 

[Anime]

The idea of the hubs on the TTB setup is that they are the weak link in the system, and so you wind up breaking a hub, which is easily replaced on the trail, rather than snapping an axle. Axles still snap with 33's or 35's, I would guess it has more to do with the gearing and the torque than the size of the tire on the wheel. Locking diffs also help with breaking things, especially if you are used to wheeling with open diffs. If you know how to get the most from a rig with lockers, they are better in many ways, but if you treat a locked rig like it has open diffs, stuff is going to snap and pop.

Generally axles snap when the driveline is engaged and there's more resistance preventing the wheel from rolling over the obstacle than the tire trying to roll over it, the vehicle it's attached to, and the torque from the engine in it can overcome, and because the driver keeps the throttle down instead of backing off and taking a different line so the vehicle can overcome the obstacle, stuff breaks. You can easily avoid snapping axles by not being stupid and trying to just drive over everything with brute force. The Explorer with a stock or modded V6 also doesn't present the same risk of breaking things as a rig with a blown V8 with 2-3 times the torque, so that helps as well, you can generally do more and worry less when you have a motor that's more along the lines of what you need, rather than total overkill. It can still break stuff, especially the hubs, but it's at least less likely.

I'd say 33's with 4.56's are what you want for the trail, those with 35's do okay with 4.56, but 35's might be better with 4.88's, some even do 5.13's.

I'd also say 33's are 'better' for a daily driver, with 35's being more of the trail rig setup. 35's with the 4.56 will be decent for on-road use. The lower weight and smaller diameter of the 33's also puts less stress on the hubs and axles.

If you have 35's now you can always throw those on and see how it does. If you're not happy, and re-gearing is too expensive/too much hassle or not an option, maybe you could sell or trade the 35's for a set of 33's.

 

[sirhk100]

Thanks for the feedback! Appreciated!

Hopefully this isn't confusing but...

My current situation is I own a set of 33's on bead locks and also another set of 35's also on beadlocks. The 35's are currently on the explorer and the 33's are on my other desert truck. The both currently have the same lug pattern so I can try both out easily on the explorer. I already have front and rear geared axles for the explorer with 4.56 so that's already done. Currently my auto, 35's, 4.56... I wish I had a bit more power. This new one I'm possibly picking up this weekend though is 5 speed manual with a 35K mile ford crate motor in it so chances are, those two variables alone will make the difference in power I'm looking for. So power wise I feel I'm fine with either tires. Axle wise, I totally get what you're saying. I've grown up wheeling in both open and locked vehicles of different types and haven't snapped an axle since high school almost 20 years ago. I do know though that typically jeeps with a D35 rear, rule of thumb is 33's are about max and 35's are really pushing it. Wasn't sure if that's kinda rule of thumb on the TTB 35's too. I know on my old explorer I had the hub fail the very first time I ever took it out. Swapped on manuals (33's and 4.56) and never had an issue again.

Honestly, right now, I'm leaning towards 33's on the expo cause of rear wheel well clearance, gas milage, wear and tear, etc... My current one which I'm going to use the parts from on the new one is tubbed in the rear which is cool but I don't plan on doing to the new one cause I want the interior 100% stock for sleeping/camping options.

 

[jd4242]

If its a crawler lock it.open sucks also go big if its just for off road.33=4.88 & 35 =5.13.I run 33 street tires with 4.88s and its not highway idle but got huge balls.but my off road tires are 36x14.50, same gear and im aussie locked front and back.all I have broke is the stock manual hubs.its about how you drive to what you will break.dont fear the gear!!

 

[RangerX]

Khris, you remember my truck. I ran 37's with front and rear lockers for 6 years or so, and only broke two hubs and one stub shaft. All breakage came when the wheels fully turned to lock and trying to climb something near vertical.
I wheeled Moab and the Rubicon without breakage. As long as you remember you're not in one of your other trucks, you should be okay with 35's.

PS I stepped down to 35's in 2011 and brought the truck to Kauai.

 

[jd4242]

Khris, you remember my truck. I ran 37's with front and rear lockers for 6 years or so, and only broke two hubs and one stub shaft. All breakage came when the wheels fully turned to lock and trying to climb something near vertical.
I wheeled Moab and the Rubicon without breakage. As long as you remember you're not in one of your other trucks, you should be okay with 35's.

PS I stepped down to 35's in 2011 and brought the truck to Kauai.

What gears? I only ran one hub locked till I thought I needed it and thats how im sure I broke my one hub.pushing one hub to far on rocks.

 

[sirhk100]

Bill, I absolutely remember your truck in truckhaven! Hard to forget it for sure! Nice choice on the move though! I have to say I'm a bit jealous!

I guess for the most part it sounds like I'm pretty safe on 33s or 35s so I suppose I'll just figure out which size I want to run on the other truck and what's left will go on the expo. Unless I just find more 35's and make them the same! LOL

 

[cmhaah06]

I'd say for mild crawling, 33's will get u every where you want to go. I was on 33's until recently and ran some wild trails. When I was on a trail and had to drag the rig a little, I did. When the obstacle was just way to big, I chose another line. Yes, it sucks not conquering a obstacle cause you dont have the clearance but I lived to finish the trail. Remember, its 90% driver and only 10% rig. Or the other way around, I dont know.

 

[RangerX]

What gears? I only ran one hub locked till I thought I needed it and thats how im sure I broke my one hub.pushing one hub to far on rocks.

Oh sorry. 4.56. I had them put in when I went to 33's. Then went to 35's. Then 37's and the lockers. I never did the one unlocked hub trick, maybe it would have saved me!

 

[sirhk100]

I'd say for mild crawling, 33's will get u every where you want to go. I was on 33's until recently and ran some wild trails. When I was on a trail and had to drag the rig a little, I did. When the obstacle was just way to big, I chose another line. Yes, it sucks not conquering a obstacle cause you dont have the clearance but I lived to finish the trail. Remember, its 90% driver and only 10% rig. Or the other way around, I dont know.

Yeah, I know all about the driver... Last time I had my Jeep out (bad word I know...) I remember following a guy on 37's locked front and rear. I was on 33's and open. I went everywhere he did that day with out issue and no bypasses and he was actually annoyed! LOL

I know 33's or 35's will get me everywhere I want to go, especially with this locker up front on this thing if I pick it up this weekend. Just wasn't sure what was "too much" for the stock stuff. I'm pretty excited to hopefully pick up this new ride tomorrow and then tear into it come March time frame and hopefully be back in the trails with 4WL rather then doing 80 thru the whoops. Both are a blast but very different! One is more adrenalin oriented where the other is more chess and challenging like.

I'll probably do a build thread since it should be a relatively quick build having all the parts on hand to do the work already and just lacking the vehicle rather then the long drawn out multi year type deal.

 

[FROADER]

Khris - My first explorer had 35s, 4.56s and an LSD in the front. I never broke anything with all of the wheeling (Truckhaven, Moab, Rubicon x2) I did in that thing.

 

[sirhk100]

Well definitely gives me piece of mind! I'm not a super aggressive hard throttle type wheeler so I'm pretty sure I'll be fine. I keep full throttle stuff reserved for the other offroad vehicles in the driveway! LOL

 

[4x4junkie]

I do know though that typically jeeps with a D35 rear, rule of thumb is 33's are about max and 35's are really pushing it. Wasn't sure if that's kinda rule of thumb on the TTB 35's too.

Yeah, doesn't really translate over the same.
The D35 in a Jeep is out back, where ours are up front. Typically a vehicle's rear axle is doing 60-80% of the work when climbing up a steep hill or other obstacle, so it only makes sense to see more rear axles fail than fronts if both axles were of similar strength.
The Jeep D35 also has the added issue of a weak housing, which can put further stresses on the shafts leading to a failure as well.

Fortunately the 31-spline 8.8" (being larger) is also well-up to the task here.
You should be fine.

 

[sirhk100]

You know that exact thought pattern crossed my mind but I also started thinking about the fact that typically when you're gripping for traction it's your front tires that are doing more that that spinning then instant grippage deal and chattering for grip which I'm sure is a pretty excessive spike in torque and force on them.

Either way though, sounds like I'm pretty well off with either tire at this point. Just hoping the expo I'm looking at tomorrow is worth the cash and it comes home with me.

 

[4x4junkie]

It's due to weight shift toward the rear when the rig is pointed up a hill. With less weight on the front, the tires can claw & try to grab all they want, but will only be able to gain so much in the way of traction (and is what tends to limit the frontend's pulling ability in the range of 20-40%). An obvious exception to this would be if you're in reverse... You probably wouldn't want to make a habit of stabbing the throttle hard backward up a steep hill lol.

 

[RangerX]

So?? It's Monday, do you have a new Ex???

 

[sirhk100]

I do actually... I'd post pictures but didn't take any. It's just your average '91 exploder. Same red color that my old one was actually. Interior is pretty good. I'll swap headliners out and may swap dashes too. If I do that, the interior will be probably an 8 out of 10, maybe even a 9. It's pretty clean!

Mechanical, not a single drop or oil underneath and it wasn't detailed, still nice and dusty on the bottom so I know it wasn't just detailed to cover up oil leaks or anything. I've got a stack of receipts pushing close to $6K in parts alone that have been put on it in the last 30K miles. Crate motor, rebuilt trans, new starter, alt. a/c pump and lines, heater core, radiator, hoses, etc etc etc...

Only issue I had on the way home was due to it sitting for the last 4 months I'm assuming. Had a minor fire in the blower motor area. Basically upon inspection looks like something attempted but failed to nest in the squirrel cage. The results were some bird seed and a couple small sticks were up in there and jammed the blower motor which caused the issue. No biggie... Took about 30 minutes sat night to pull apart, clean it out and get it back together. Only part the sucks is now the expo smells like smoke, fire smoke, not cigarette smoke. Hopefully that'll go away with time and windows down.

I've driven it 2 days now and so far haven't found a single issue with it. Everything works, everything feels tight, no rattles, drives nice, etc... Now I just need to button up this race truck and get it out of my garage so I can pull dive into the explorer project! I'll take pictures and do a build thread cause it should go pretty fast considering I've got all the parts on hand.

It's currently sitting on 31's, has a locker up front and has the james duff single tube radius arms with the trans crossmember. It's sitting stock height though. That was actually part of why the owner sold it. He wanted to go to larger tires but didn't want to go drop brackets but couldn't afford to go custom beams and everything so he instead bought a cherokee and changed vehicles altogether. I'll pop the locker out of this 3rd and put it in my other one that's already got 4.56 gears in it. Slap my whole front suspension on it and fab up some upper shock mounts for the coilovers. Swap out 100% of the rear suspension on it for my deavers and shackles and even the whole rear axle since mine already has 4.56 and is a newer disc brake unit. Get the interior pieces swapped out and mount up the fiberglass. Get it painted and it should be good to go!

Oh and it's the manual t-case too btw!!!! Pretty stoked on that and I'm amazed how smooth it engages between 2wd/4wd/N/4lo. Just pulls right in and out with no issues! I'm used to my old jeep that had to grind it's way back and forth and you really had to muscle it in and out.

Any ideas for getting rid of smoke smell though?