Sooo, what damage will big tires do to the rig? (1 Viewer)

[e9999]

all right, so it's been amply made clear that we all gotta put on the biggest tires that will possibly fit without rubbing, and then some... otherwise we are no real men and barely qualify as pansies
and, yes, I imagine if you get big ones you may need to regear if you want to go uphill at a reasonable clip (let's not even mention the 91s and 92s when one talks about uphill and reasonable clip in the same sentence, eh... ).

But what's not so clear to me is what the result of the process is likely to be. IOW, what do big tires do to the rig? I imagine heavier tires would likely increase the stress on the suspension, bearings, birfs (oh, the horror...!) etc. Is this likely to result in accelerated wear and possibly damage, even with only street driving?

Any serious info out there on what damage if any would result from the use of bigger tires (say 35") if one were to limit oneself to light off-roading (read no Moab stuff)? Any parts particularly likely to fail?

thoughts?
thanks
Eric

 

[NW-sickboy]

i dont know of any write ups on every part that wears more but why would you go to say a 35 if your doing mild wheeling? obviosly all the things you mentioned are affected. Birfs prolly first.....and then any other drive train problem that you had .....but was small...will now become worse faster........but.....i think i lot of board members could attest to is that a locked rig with some mild protection and 33s will do all the mild wheeling you want......without major wear, regearing.....and the useal list of problems that J springs and 35s bring........BTW i run 37s and wouldnt have it any other. way.....it defines my manhood

 

[landtank]

Putting big tires on by itself does stress the drive train all the way back to the engine. However once you regear that stress is then shifted back out to the diffs and birfs. The actual point is the ring gear as the pinion has the mechanical advantage over it. However not many R&Ps failing out there so the birfs are the week link. Ground clearance is usually measured between the ground and the bottom of the diff. Damn hard to increase that without putting on bigger tires. It can be done but would include swapping in portal axles.

I wanted that extra cushion that the larger tires gives me. I find some comfort in that.

I had a chance to meet up with Erics-Bruiser this past week. He stopped by with his 91 and I had a chance to drive it. Damn nice driving truck, don't know what all the negative comments about the 3FE engine are about. It moved along quite well and I only maybe felt a little difference between that truck and mine. Grant you I wasn't do quarter miles with it but I was really impressed with it.

 

[turbocruiser]

First, I am no expert, but I wonder why you would want 35's for mild offroading? 33's will work well for what you think you will do. Second, from your post you are mostly concerned about on road performance and one thing to think about is that the larger the tire, the more "unsprung" weight you will have riding with your suspension. This will make the suspension that much less responsive from an on road perspective. My suggestion, again I am no expert, is to use what YOU want to use for the purpose you want to use the vehicle for. Dont worry to much about pansy status, just worry about what works for you. I think you would be wonderfully happy with 33's and also less concerned about what might snap. Just an opinion. Thanks.

 

[xl715]

I'm running 35's, and without doing everything right, the rig will not drive right. This includes caster, swaybars, brakelines, ect,ect. Just putting on J springs and 35's will fit, (I did it) however, everytime I pulled in my driveway I would rub drivers front tire. Never took it off road like that it would have been worse than stock!!! As far as wear goes, of course it's going to wear out birfs and bearings a little faster, how fast?, proly depends on your specific rig. But if you are looking to run 35's for offroad ability, then a little faster wear is just one of those things you accept as part of the plan.
Have you tried to wheel your rig the way it is and are not able to make it where you want to be going? Thats why I run 35's, but it took alot more than I thought it would to stop my rig stock with running boards!!! I was trail running with lifted heeps and 4runners, makeing it everywere they did(kinda pissed them off that a stockLC was that capable!!

 

[e9999]

thanks for the reality check folks, as usual, you guys are coming through. Personally, I would not put 35" on for mostly road-driving. Although I imagine it could be useful for a number of situations that do not involve "extreme" off-roading as in rock crawling.
My question was more a technical one namely wondering what parts are more likely to fail with the bigger tires than without, since we read some much about the big ones.
(and the fact that there is a 35" tire '97 around town that is not selling has nothing to do with it... )

sooo, leaving aside whether 35" are appropriate or not to a specific type of wheeling for now, is there any evidence that some parts are failing at a higher rate than normal with big tires on, and if so, which ones?

thx
Eric

 

[ginericLC]

Bearings maybe? But maintainence can deal with that. My biggest complaint is the lack of braking and brake pad, rotor wear. Suspension and shock life really isn't much of an issue as you have probably already modified that to fit the big tires. Steering componets. I know that my pump has to work harder to turn the big tires. More stress on the box and tie rod ends. Definitely birfs, but really you probably don't measure the wear until they SNAP! And I don't think 35s in most situations are going to create the SNAP.

 

[Hltoppr]

I run HUGE 31x10.5s...

Haven't had any issues in not being able to get somewhere I need to go, but then again I'm not afraid of throwing on a pack and walking too.

-H-

 

[ginericLC]

"Haven't had any issues in not being able to get somewhere I need to go, but then again I'm not afraid of throwing on a pack and walking too."

You might get there quicker by walking than driving a 3FE powered 80 with anything more than 31s. I have to do my Fred Flinstone impersonation when I drive our 91.

 

[landtank]

XL715, sounds like you're not running factory rims. Are you?

 

[PHAEDRUS]

OK
enought with the 3FE bashing for those of you who don't own one you are talking directly out of your superior asses@!!!!!
ok just a little vent here. I love my 3FE and I am running 33" tires and it still will do 75-80 on the freeway if I need it to. as far as stresses and additional wear points from what I have gathered the breaking point with birfs seems to be in the above 35" tire point. personally for the type of wheeling I do (including the big rock Moab fun) I like my 33" tires and tehy serve my purposes well and still maintain decent driveablility.
I think after birfs and r&p wear the next weak link will be in the drive lines.
again not trying to flame anyone here but until you have driven a 3FE with 33"s and then hopped in a 1FZE with 33" tires for a direct test get off the dang bandwagon.
Dave
(donning the asbestos suit again)

 

[landtank]

Dave, Erics truck had the 16" rims mounted on as well. Granted I have a gearing advantage as well as the bigger engine but the difference wasn't that noticable. My daughter is going to need a vehicle next year. If I can find one like Erics for a similar price and she'll be driving one.

 

[PHAEDRUS]

sorry about that just re read my post and probably went of a little deep. for simplicity and lack of the head gasket issues I love the 3FE. for a younger driver I think they are excellent. just fast enough to do what you need to do.
Dave

 

[ginericLC]

[quote author=Phaedrus link=board=2;threadid=11447;start=msg104404#msg104404 date=1076699904]
OK
enought with the 3FE bashing for those of you who don't own one you are talking directly out of your superior asses@!!!!!
ok just a little vent here. I love my 3FE and I am running 33" tires and it still will do 75-80 on the freeway if I need it to. as far as stresses and additional wear points from what I have gathered the breaking point with birfs seems to be in the above 35" tire point. personally for the type of wheeling I do (including the big rock Moab fun) I like my 33" tires and tehy serve my purposes well and still maintain decent driveablility.
I think after birfs and r&p wear the next weak link will be in the drive lines.
again not trying to flame anyone here but until you have driven a 3FE with 33"s and then hopped in a 1FZE with 33" tires for a direct test get off the dang bandwagon.
Dave
(donning the asbestos suit again)
[/quote]

Read my sig line! I have both. And I have driven both with the same exact tires and wheels on both. Maybe the difference is elevation I'm at? or maybe it is that our speed limit is 75 in Idaho. And I really like the 3FE as a motor, just not in an 80 series, it is nice in a 62. And really the wear issues of going to bigger tires is not going to effected much by having a 3FE or 1FZ which what this thread is about.

 

[IdahoDoug]

Regarding the relationship between birf failure and tire size - I don't agree there is any, other than a side effect. By that, I mean the size of the tire doesn't increase the stress on the birfield. The birfield is stressed by engine torque, and also by sharp steering angles with high torque applied. Neither changes when you put a larger tire on.

What relationship exists between birf failures and larger tires is, I believe, due to the likelihood that larger tired rigs tend to be offroaded more often, and more heavily, perhaps have power mods, and perhaps not have their birf maintenance elevated to offset the usage. With a higher percentage of usage in tough offroading being the real reason more birfs fail on these rigs.

A simple way to think of my point is to imagine the torque transmitted through the birfs as X. Put larger tires on it and the torque transmitted is still X.

 

[Bob_Garrett]

Eric,

I ran 33s on my rig for about 50k mi before switching to 35s about 2 years ago. Have done about 25k since going to 35s and about 10k since regearing. Only additional wear I have seen is that the wheel bearings seem to loosen up a little more often and I have had to replace one of the axle oil seals after about 15k mi. With the 35s and stock gears, it seemed that the engine and tranny were working harder, but seemed to suffer no ill effects. With 4:56s in it, the rig is back to nearly stock performance and feels much less stressed in highway and trail driving.

As far as highway handling is concerned, moving up to 35s and J-springs caused a significant degradation in that area. Much worse than with the standard OME and 33s. I am hoping that the installation of Slee's front control arms and lenghening of the panhard rods will restore at least some of the original handling.

Bob

Bob

 

[landtank]

Yes Doug with larger tires the torque doesn't increase however your traction does. Basically more stress will build up in the drive line from the lack of wheel spin increasing the risk of failure. And because of this, if you do loose traction for a bit when the wheel does regain traction it is at a higher force increasing the stress on the birfield.

 

[ginericLC]

[quote author=IdahoDoug link=board=2;threadid=11447;start=msg104463#msg104463 date=1076707645]
Regarding the relationship between birf failure and tire size - I don't agree there is any, other than a side effect. By that, I mean the size of the tire doesn't increase the stress on the birfield. The birfield is stressed by engine torque, and also by sharp steering angles with high torque applied. Neither changes when you put a larger tire on.

What relationship exists between birf failures and larger tires is, I believe, due to the likelihood that larger tired rigs tend to be offroaded more often, and more heavily, perhaps have power mods, and perhaps not have their birf maintenance elevated to offset the usage. With a higher percentage of usage in tough offroading being the real reason more birfs fail on these rigs.

A simple way to think of my point is to imagine the torque transmitted through the birfs as X. Put larger tires on it and the torque transmitted is still X.
[/quote]

The torque isn't same. The added weight and rotational forces is greater on a larger tires. Imagine the pesky nut you can't get off. You apply more torque with a longer wrench to get it off. The torque required to move a larger tire is more than a smaller tire. Since the torque is transmitted through the birfield to get from the axle to the wheel this added torque is transmitted through the birfield.

In the below formula, a larger wheel increases the distance.

Torque is the force that produces rotation. It causes an object to rotate. Torque consist of a force acting on distance. Torque, like work, is measured is pound-feet (lb-ft). However, torque, unlike work, may exist even though no movement occurs.

To calculate torque, apply this formula:

T = F x D

T = torque (in lb-ft)
F = force (in lb)
D = distance (in ft)

 

[IdahoDoug]

Rick,

I agree with your scenario. However, those conditions would only be encountered in fairly challenging offroad conditions (high traction rock so steep you're slipping and generating wheelspin). I think it's still more accurate to tie a birf failure to the use of the rig rather than solely to the tire since you could drive a large tired vehicle for decades and never generate more force upon its birfields. Another way of saying it is that the ONLY way to generate more force on a large tired rig is to generate wheelspin and have it hook up suddenly.

Doug

 

[landtank]

I don't think that's the only scenario. Manuvering with bigger tires would produce more stress as wheel slip would be reduced. This would require the CDL to be engaged but would increase if the axles would be locked as well. Ask Junk about the scenario in his back yard.