two sets of tires on FJ80 (1 Viewer)

[Pauli]

hi, i will straight up admit to my lack of automotive know how
my '97 landcrusier has 2 cooper discoverer m&s 265/75r/16, new as of july, on the front
the back two tires (same model) are pretty close to being done
looked around to find new/solid used discoverers locally without luck
seems cooper discontinued the model/style
mechanic says being a full time 4wd means buying 4 new tires
because the difference in tread styles with newer model or any style will mess up
the drive train
i am just starting the research part on this situation and thought i would start here for comments
thank you all very much

 

[Dusten]

The front and rear tires need to spin at the same speed to avoid damage to the transfer case.
In theory a comparable tire of the same style from the same manufacturer should work.

Ie: xyz tire company make the at2. They discontinue it and make the at3 now. New tread pattern but same basic tire. I wouldnt hesitate to run 2 of them with 2 of the others.
I would not run 2 different brands.

 

[ppc]

The critical factor is matching tire diameter/circumference on all four tires.

 

[Dusten]

The critical factor is matching tire diameter/circumference on all four tires.

This is why I wouldn't run 2 different brands. One 265/85 isn't the same as another.

 

[ppc]

This is why I wouldn't run 2 different brands. One 265/85 isn't the same as another.

But also a reason not to run a used tire of the same mode!/construction without measuring tread depth.

 

[Dusten]

But also a reason not to run a used tire of the same mode!/construction without measuring tread depth.

Now I'm curious what the allowable variance is.

 

[jpoole]

Allowable variance will be pretty low for a later FZJ80 with the viscous coupler still in place. Think about cruising down the highway with the VC constantly working to some extent, it wouldn't take much to heat it up. With no VC there will be more tolerance for variance.

My 80 came with 4 different tires with both mixed manufacturers and sizes! VC had been baked to brick status.

 

[Dusten]

Allowable variance will be pretty low for a later FZJ80 with the viscous coupler still in place. Think about cruising down the highway with the VC constantly working to some extent, it wouldn't take much to heat it up. With no VC there will be more tolerance for variance.

My 80 came with 4 different tires with both mixed manufacturers sizes! VC had been baked to brick status.

I'm aware. But there has to be some variance in place for tire wear. Inexact manufacturing process.

 

[jpoole]

@Pauli is this your tire:

Cooper Discoverer M+S Winter Tire - 265/75R16 116S - Walmart.com

Buy Cooper Discoverer M+S Winter Tire - 265/75R16 116S at Walmart.com

www.walmart.com

Even if it's not I'd look online for a pair of new tires that match what you have up front. If they were new in July surely one of the larger retailers/suppliers still has a few on a shelf somewhere.

Also, regarding tire size matching and Viscous Couplers, a quick test to see if your VC is still in place could help you decide if all of this VC talk even matters to you. Yours may be long gone and thus none of this relevant. There are a lot of discussions on VCs on mud so if you want to read up on them and learn how to test if you have one (relatively easy) dig in below:

Diagnosing CDL or Viscous Coupler Problem

CDL Actuator Problem I know it has been talked to death but I wanted to clarify something before I get my tools. Problem: Pulling into parking space or making a tight turn at slow speeds, my front tires grab/chirp/etc. From what I have researched, it is either a CDL problem or VC...

forum.ih8mud.com

Viscous coupling ...

Is it possible to un-seize a seized viscous coupling. ... if it is ... how is it done??

forum.ih8mud.com

Viscous Coupler Going Bad??

I drove my sister's '95 and it almost seems like the center diff is locked, however it is not. It is hard to turn at low speeds, tires chirp, and the drive line has noticeable bind. When I lock the center diff it gets really hard to turn, etc, etc which tells me it is locking and unlocking...

forum.ih8mud.com

Tutorial: removing the viscous coupler (photos)

What pushed me to do the viscous coupler removal? First of all when I made turns, for example, in a parking lot, I heard my tires scrub against concrete and one of the wheel stopped turning intermittently to relieve the stress on the drivetrain. Please note that my tires weren't squeaking but...

forum.ih8mud.com

more - google search: viscous coupler site:ih8mud.com​

@Dusten Yeah, I'm guessing the designing engineers specified a VC that could tolerate normal variances that would occur with matched set of tires that were rotated as directed. Toyota probably included clear directives on only running matched sets of tires and to rotate those tires on 80s. I'd be surprised if they published a tire size variance limit though.

The VC is going to be worked when turning and a little under all conditions just because the balance between wheel speeds will never be perfect. The VCs ability to shed heat and protect the silicon fluid from wear/burning is going to guide the variance limit. If you want to keep a VC in one of these you'll want to minimize wear on it at all times and I don't think you'd ever chose to run a mismatched set of tires, even from the same manufacturer. I'd expect the 80 VC to be more robust than most but still it can only tolerate so much use and many of us have pulled ours after they stiffened up.

Even when tires are always matched I think the VCs will still wear out with enough miles and heat cycles. Makes me wonder what the longevity of VCs are across the many vehicles that use them in AWD setups. Most seem to get cooked but I don't know if it's from abuse (overheating events) or if they just wear out with time under normal wear/heat. The VC in the transfer is a lot like the fan clutch which also seems to have a predictably limited service life so maybe the silicone fluid wears out after x heat cycles/etc. or maybe failure is more related to overheating events? I bet some folks on mud know

 

[Pauli]

thanks to everyone adding the info above. much appreciated.
yes jpoole, that shot is of the tires on now. i just got off that retailers site and saw they were out of stock. i was looking at the same mfg/model only "A/T all season" not M&S, same size etc. costing $115. thinking that despite the VC talk above this tire could be a reasonable replacement. i will have to dig deeper on the VC links and observations. honestly, though i have heard the term, no idea what it is (but in 24hrs I will...LOL) i have no doubt my VC is also baked to brick status as i am hitting 200,000 and the tires have come and gone depending on the moths flying out of my wallet. maybe the CARES act thru congress has a line item on tires for vets.

 

[flintknapper]

i have no doubt my VC is also baked to brick status as i am hitting 200,000

Not necessarily. I have 328K on mine and its still working (or at least not causing me issues).

I don't know if anyone mentioned it...but IF/When your VC goes....you can just pluck it out of the Transfer Case and go on your merry way.

 

[Pauli]

thanks deep east texas
i will keep this in mind as i pour over the decision tree