Unsprung weight & grenading weak rear diff - Wheel/Tire consideration

[jewishoverlander]

Lets keep this short and sweet. I dont know enough about 4x4s to answer this question with any accuracy.
I have GX470 with the infamously weak 8" rear diff.

The question is, are there people with enough 4x4 experience and wrenching experience to make an educated guess as to whether a reasonable overall total rig weight but a 30--40% increase in unsprung weight at the wheels compared to stock is going to increase significantly my chance to blow the diff assuming all else is equal?

The stock wheel + tire combo is 63lbs (25lbs and 38lbs respectively)
The tire I want is the Kenda RT 33x10.5 but it comes in at 61lbs just for the tire. Until I get new wheels (I will buy somehting lighter than 25lbs) I will be nearly 40% heavier in unsprung weight than stock.

Obviously there are cars that make it and cars that dont, just like people who smoke for 40 years and healthy and those who smoked for 5 and got lung cancer. I know nothing is a for sure thing. Im trying to make an educated guess of whether I should consider a lighter tire. The best other tire for me I would think is the Wildpeak AT3W tho Im not sure its aggressive enough for my needs. Im not doing the Rubicon anytime soon but I do plan to crawl. My main off-road buddy is a JLU on 35s going to 37s soon. So I will likely end up on trails that he will have to yank me a few times.

 

[Buddha.]

I think grenading the diff is more a result of too much skinny pedal and alternating low traction/high traction situations.
Knowing nothing about your rig I’d think you’d be fine if you take it easy.

 

[IdaSHO]

Correct. Limit the shock loads (mentioned alternating traction/no traction) and things last a LOT longer.

 

[kayadog]

Are these Kenda RT 33x10.50r17? 61lbs. Sounds too heavy. I think I read they are 47lbs. each.

 

[NatersXJ6]

I have them, but I’m not planning to put one on a scale unless beer pours out of it.

 

[jewishoverlander]

Are these Kenda RT 33x10.50r17? 61lbs. Sounds too heavy. I think I read they are 47lbs. each.

I read that too on Tacoma world. Then I most commonly read 52lbs but I spoke to them on the phone today and they said 61lbs. I will call again tomorrow and 100% confirm we're talking about the right tire.
For the 52lbs that mostly gets spread she said she thinks it was a typo in an email that was meant to say 62lbs because its slightly above 61lbs.
I had already been set on them when I believed they were 52lbs....

I have them, but I’m not planning to put one on a scale unless beer pours out of it.

IF you have them not on a wheel, would be awesome if you can weigh yourself, then pick one up and weigh again and see!

 

[NatersXJ6]

I read that too on Tacoma world. Then I most commonly read 52lbs but I spoke to them on the phone today and they said 61lbs. I will call again tomorrow and 100% confirm we're talking about the right tire.
For the 52lbs that mostly gets spread she said she thinks it was a typo in an email that was meant to say 62lbs because its slightly above 61lbs.
I had already been set on them when I believed they were 52lbs....



IF you have them not on a wheel, would be awesome if you can weigh yourself, then pick one up and weigh again and see!

They are already mounted. I’ll see if I can pull the spare off and weigh a wheel too. That will get you down to only air and negligible other differences. I will say, they are notably heavier than the stock tires for the JK Rubicon. The diameter is close enough that a GPS speedometer still matches the factory setting with no changes, but it holds gears longer and has more drag. They are quieter and smoother and I expected a slight mpg uptick, but it has actually fallen slightly. I’m trying to figure out if something is wrong or if they are just heavy tires.

 

[vtsoundman]

Large rotating mass impacts bearing and ball joints the most. Then arms, bushings and the like...(in that order). Shock loading (peeling out in dirt then hitting pavement, rocking up/down rocks, throttle) breaks diffs. Big tires do excerbate shock loading...

The 8" diff breaks because of shock and sustained loading...not big tires.

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[MTVR]

There's a lot of good info in the responses to the OP's initial post.

I will add that there is not a particular "line" where things go from 100% safe to instantly exploding- it has more to do with statistical probability.

Rear ends do fail on well-maintained 100% stock vehicles that are used only for solo slabbing on the Interstate, without ever towing, hauling, going off road, or even being exposed to large throttle openings, sometimes at surprisingly low mileages- but it doesn't happen often.

At the other end of the scale are people who put 44" Interco Boggers on ancient stock Toyota axles, and abuse them at full throttle constantly with zero maintenance, without ever suffering a mechanical failure- but that doesn't happen often either.

In the middle, are the rest of us- we modify our vehicles and drive them in a manner and to the degree of risk that we are willing to accept. Larger and/or heavier tires increase that risk. Abusive driving increases that risk. Sometimes it works out for us, and sometimes it doesn't...