Convince me to get 33s instead of 35s... or not

[Rymanrph]

As soon as my car sells, I'm going to be upgrading the MJ to SOA in the rear and long arms up front with ACOS to level it out. I'll be regearing and I'm looking at adding Bushwacker's flat style flares. I was convinced that I was going to pick 4.56 gears and 33s, but I keep getting drawn to 35s (they just look right). I won't get to take this truck off road as much as I'll want to, but I don't want to gear for 33s and then upgrade to 35s later. It will be my daily driver for a while and it will be city traffic, but the whole point of upgrading is so that I can take it off road on occasion and enjoy it. Maybe I just need to see some pictures of some great looking Comanches on 33s. Thoughts?

[reece146]

Please don't ruin your beautiful truck by putting Bushcrackers and 35s on it.

 

What size are you running now?

 

I wouldn't go any larger than a 32 or 265/75-16. Keep the factory flares.

 

2¢

[Pete M]

have yet to be in a situation where 35s would have saved me. :dunno:

 

 

 

 

[mvusse]

When I ran 33s, things were okay. Then it was time for new tires and I moved up to 35s because they were almost the same price as 33s at t he time. That's when the trouble sterted.

 

I go through unit bearings almost monthly.

An axle shafts or u joints every two months or so.

And gas mileage is down the drain. On the 33s I could manage 19mpg, on the 35s I can only do 14, so no more daily driver.

 

I also had to cut to make them fit properly and still bump stop pretty aggressively in the front because once they cleared the sheet metal the inner fender itself got in their way when stuffed.

 

I'm SOA in the rear, 6.25" in front.

[Motion Offroad]

Hmmm... the good 33" vs 35" debate on the XJ/MJ....

 

As someone who runs both 33's and 35's on their daily drivers I figured I'd put my $0.02 worth in.

 

My wife runs 33's on her daily driver XJ with 3.5" longarm lift (with factory flares). This sees a lot of road use (this is what we take on trips most of the time) and it does also get wheeled quite often. She love the way it feels both on and off-road. She wanted 33" tires and wanted it as low to the ground as possible (she wanted to still be able to get into it relatively easy). I as her husband wanted it to be safe for her while on the road with our kids. The 3.5"/33 combo has worked well for us the past 5 years.

 

On my XJ I run 35's with a 5" lift and minor trimming. I did daily drive this for years and really had no complaints about it. Yes gas mileage sucked but I account that to the 4.6L motor more than the 35" tires. It got wheeled hard offroad and I really liked the 35" tires.

 

Now moving onto the MJ that was built for offroad use only. I ran 35" tires on that for several years before I bumped upto 37's. Honestly the reasoning behind the 35" tires was due to going SOA in the rear. Your going to get close to that 6" lift mark and I just felt like the 33's were to small. I love the extra ground clearance with the 35's and honestly that reason I went to 37's was I felt that the 35's where to small. With that being said this MJ never saw on-road use.

 

If your doing it right (as in using quality components) for the lift, the cost really isn't much different to lift it for a set of 33's vs. a set of 35's. What you really need to consider is the cost of axle upgrades needed for the set of 35's. Depending on what axles your currently running I'd recommend having a D44 or 8.8" or, 29spln 8.25" under it. Marcel stated he had issues with u-joints, shafts and wheel bearings; I have never with the 35's and wheel quite hard. Not sure what the difference is (maybe brand of parts, I dunno...).

 

Honestly what it's going to come down to is what YOU want. I think based on your build you have a pretty good concept of what it takes to do things right. Overall it's going to probably cost you a bit more to run the 35's than the 33's. Just remember that if you want to keep it as DD duties just don't OVER BUILD it or it'll be no fun to drive. Thats what happened to my XJ and it just sits now and gets wheeled every so often.

[SW86]

i went 305s which are a true 33. mine are 33.1 actually. plus 33s make the harder trails a challenge but if your locked front/rear you could even run 31s and keep up with the big dogs. ground clearance might suffer but thats what belly protection is all about. for what your talking about doing go 33s. you won't regret it. i went 6.5 and SOA and its perfect to me. looks, function, everything. when i wheel i go hard and its never slowed me down from following guys on 37s. sure they can make hard stuff look easy but again, wheres the fun in that if theres no challenge.

[Comanche County]

My 2 cents, FWIW:

 

First, a disclaimer: I'm no metallurgist, professional axle builder, or even someone that thinks they're smart,,,,and I know people will disagree with me because of their experiences but here goes....

 

Contrary to the commonly accepted belief that 37"/38" or larger tires are the thresh hold for full floating axles, I believe 35's are the thresh hold for full floating 3/4-1 ton axles. Why run a tire that you know will break parts, because there's no such thing as easy wheeling. Its a simple physics issue. That much mass when spinning will break most stock sized axle shafts as they catch and lose traction, even replacement alloy axle shafts. I run a HP44 up front with 1.34" 4340 alloy axle shafts and although there's been no axle shaft or diff issues, I just had to replace unit bearings and 1330 ujoints. The rear is a stock 44 with stock shafts with 1310 joints that are also on the way out. The rear axle is holding up so far but the possibility for breakage is always in the back of my mind. I'd rather have built the MJ with full width HD full floating axles with the piece of mind that I'll make it home since I also wheel alone often. Not to mention the safety aspect.

 

Here's why I say 35s are the thresh hold for bigger axles. Not all 33s or 35s are the same. Its easy to find similar sized tires with dissimilar mass. Larger tires have more leverage, heavier tires have more mass and thus more energy while in motion. For instance, my 35"/12.5"/15" Dick Cepek Fun Country IIs on 15" Steel D windows weigh 90 lbs each, while my 35"/12.5"/16" Maxxis Creepy Crawlers on 16" steel Soft 8s weigh 102 lbs each. That 12 lb difference translates into a big MPG disparity and a severe difference in rotational mass and energy. Compared to the weight of stock tires that difference is truly immense and kinda scary if you think about the possibility of your larger off road tire weighing somewhere around 100 lbs breaking off your stock axle and smashing through a mini-van full of 8 year old girls on their way to ballet lessons. Not a pretty thought is it?

 

I wish I could compare the weights of these larger sizes accurately to stock size tires but I couldn't. I tried to weigh a set of 235/75/15s on aluminum Canyons but they wouldn't even trigger my cheapo electric bathroom scale. I figure they're in the 30-40 lb range. Someone here ought to be able to give us the weight of stock wheels/tires. If someone can do that, you'll see that 35s, even 33s, will weigh at least twice as much as stock tires. When you spin larger tires, you need more beef to keep them under the vehicle while not having parts and fly off taking the unit bearing or rear axle shaft with it. IMO, 35s have no place on a D30 or D35, 8.25 (27 or 29 spline), or even a stock D44 even though that's what I've got. They will eventually break those axle shafts, its just a matter of time. 33s may also, but 33s, due to their lower mass, gives you a much wider range of axles to choose from and longevity of parts.

 

What I'm suggesting is a simple physics question that I'm too dumb to figure out myself but I'll try to illustrate my point as best I can. So here's what someone needs to figure out.....Here's the "The Premise": If 33"s or 35"s weigh at least 50% more than stock tires, shouldn't the rest of the axle and bearing assembly which controls that tire be at least 50% stronger or more, or whatever the difference in mass works out to be?

 

For reference, check out Randy Lyman's book on Diffs. Its worth the buy if you don't have it.

 

http://www.amazon.com/Differentials-Ide ... 156&sr=8-2

 

Section 6/2/2A-C (pages 279-292) addresses torque capacity of axle shafts and u-joints. There's a couple of great sections on the difference in strength of various u-joints and axle shaft strength with different metallurgy. However, even though you may have an axle shaft and u-joints that are strong enough to hold the rotational torque of 33s or 35s, if its not full floating, you're still risking losing a tire or breakage. And we haven't even touched on diff or axle tube strength.

 

This is why my MJ will have HD full floating 1 tons as soon as I have the dough.

 

Here's some pics of a couple of pages of Randy's book. I'm probably committing copyright infringement but I'll take the chance. The pages are glossy and had too much glare with the lights on, so I turned them off and my iphone took crappy pics....not only am I a mediocre soapboxer, I'm a crappy photographer.

 

 

 

 

 

 

Objecting opinions are welcome. But don't bring anecdotal evidence like "I've run 35s for years with no breakage" because that will simply indicate that you're a bit dense upstairs. Look at the last picture and check out the approximate strength of your axle and tire size before you object. Then answer this question: how much torque is produced by various sized tires at various RPMs in order to accurately choose an axle shaft size/heat treatment to ensure adequate strength? I'd bet the guys at Randy's or over at Currie's have already figured it out. Imagine a 102 lb 35" tire spinning at 500 RPM, just how strong of an axle shaft would you need? Once a tire size is chosen, the next choice is weight of the tire, then once you know rotational torque of the tire, then choose axles that will handle them.

 

Again, there's a reason why the manufacturers run 265/75/16s or similar size tires on 1 ton trucks with full floating axles. Perhaps they're being conservative on tire size for the purposes of axle longevity, probably so. No manufacturer will risk safety. Why should we? If you're running 35's or larger with stock Jeep axles and your rig is intended for that mythical land we all know as "the trail", okay cool, but you'll break something eventually, then you'll be stuck out there on "the trail".

 

In the risk of proving Groucho Marx's quote true that "the cliche is the crutch of a crippled mind", I'll go ahead and state that "if its worth building, its worth over building", or the ever popular "go big or go home".

 

My advice to the OP, go with 33s or smaller or go with full floating axles.

[mvusse]

Hmmm... the good 33" vs 35" debate on the XJ/MJ....

Marcel stated he had issues with u-joints, shafts and wheel bearings; I have never with the 35's and wheel quite hard. Not sure what the difference is (maybe brand of parts, I dunno...).

 

I have slowly been coming to the conclusion I am harder on my vehicle off road than most. I run stock single piece shafts, first in a disconnect axle (blew up the diff, including my Aussie 4 weeks ago), now in a non disconnect one running spider gears until I can get new pins and springs for the Aussie.

 

Moving stuff over from the old axle (that has been under my truck for 2 years and has had the diff rebuilt once already in that time) I came across a lower control arm 3/4 ripped off the axle tube, as well as a cracked axle tube. I have heard of bent axles before, never heard of a tube cracking. It ended up going to the scrap yard.

 

I used to use Neapco Brute Force and Duralast Gold u joints. They were find on stock tires, so-so on the 33s, but absolute crap for running 35s. Last few years I've been running Spicer 5-760x (non cross-drilled, cold forged replacement for the 5-297x) for ~$25 a piece. I tried a set of Alloy USA Chromoly joints last time and grendaded one of those on the first trip off road. The other one is still going after three trips.

[HKB3]

Please do not put bushwhackers on your or any MJ

Go for the 35's and 4.88s, if you get 33's you know you will wish you had gotten 35's.

Just my $.10(inflation you know)

[Rymanrph]

Please do not put bushwhackers on your or any MJ

Go for the 35's and 4.88s, if you get 33's you know you will wish you had gotten 35's.

Just my $.10(inflation you know)

 

I like the pocket style flares OK, but I'm looking at the flat style flares like on RockMJ's and buffalob's trucks (hope they don't mind me reposting).

 

 

One of my biggest reasons for the flares is so that the front and back will match. I hate having two different style flares on my truck. My concern is that with the flares opening up the wheel openings, that 33s will look too small. The silver rig above has 33s on only 4.5"s of lift. I still have my original 2wd drive leafs, so hopefully my SOA won't sit much higher than that, but it looks as though he has plenty of room for 35s.

[Pete M]

if you get 33's you know you will wish you had gotten 35's.

 

 

I don't. :dunno:

[SW86]

^^^ i don't either.. I'm happy with 33s... here's mine on 305x70x16 aka 33.07x12.01x16

 

 

 

 

 

ive got 6.5 coils and SOA 4wd springs.

[HKB3]

I did not know that bushwacker made the flat style flares for MJ/XJ, they actually look good.

[Joshestate]

Where can you get the flat style fender flares for mj?

[Smokeyyank]

14 hours ago, Joshestate said:

Where can you get the flat style fender flares for mj?

 

It's just the flat flares for the XJ. There is a slight gap in the rear for the MJ though.

 

As for the rest. I'd say it really boils down to what axle you're going to run. Personally, I'm not a fan of anything above a 33" on a D30, can you run 35's on it, absolutely. The issue becomes the cost to upgrade the D30 to effectively run 35's vs just going with a HPD44  or tons. Plus the geometry of a D30 sucks once you start getting, tall 5"+, you can do the WJ swap but it's not cheap. For my MJ I'm planning to run 33's with a decently built D30 (selectable locker, 4.56 and WJ swap) , my Xj will run a HPD44 and 9" for 35's. When I had my other XJ I had a D30 and 33's, with the exception of being on 4.11's it handled everything just fine. I found 33's a good overall size for what I was doing, mild wheeling and daily.