Driving 1 Tire Slightly Bigger Than Other 3 (1 Viewer)

[MidMan]

Does it have a viscus coupler?

Sir. Are you referring to Viscus Fan Clutch or something else in wheel hubs ?
If its Fan clutch, then yes it has.
Sorry, but yes this is my first 4x4 and i am learning alot.
I had Cars in past, but they are quite easy to maintain. But for jeeps like this, today you fix this and tomorrow you have to fix that.

 

[MidMan]

Find a used tire in the same size Or replace all 4

i am working on it and have plans to do it by this weekend.
mostly i am using my jeep as daily runner. in 1 month i drive it like 1500-2000 Km and 99% of my travelings are on Highways & Roads.
I am absolutely not using it for off-roading.
so will that be ok IF i can find some good condition 2nd hand tires, then would that be a wise decision to use them instead of buying new?

 

[MidMan]

Buy a tire with a tread warranty and if they die at 25k at least they will prorate the next set

Thank you so much sir.
but sadly this thing does not apply here in PK.
once you buy the brand new tires and step out of workshop, its all yours.
If they went well, you are lucky.
If got any damage within 6 months, they will keep telling the lame excuses till we feel totally exhausted.

 

[BILT4ME]

If you MUST drive with one odd-sized tire, keep your speed low. Speed creates heat in the differential and can cause other failures.

I did this in a 1972 Chrysler Town and Country wagon and one rear tire 2" larger in diameter. At 100 MPH, the rear differential overheated and broke the pinion in half and started the rear axle gear oil on fire. This happened in 13 miles.

 

[jpoole]

@MidMan I'll try to explain the Viscous Coupler (VC) topic a bit even though I'm less qualified than many to do so.

he viscous coupler, if your 80 has one, is in the transfer case and was a core component of the All Wheel Drive functionality for the 80 series land cruisers equipped with them. In the North American market most (if not all) of the FZJ80s were equipped with the Viscous coupler from the factory (after 92 perhaps, but I don't remember exactly). The "all wheel drive" 80s with a VC don't have the ability to be shifted into two wheel drive and don't have front locking hubs, etc.. Globally there was a lot more variety and some 80s have part time or 2wd/4wd operating modes etc. (as I understand it) and some 80s didn't have the viscous coupler from the factory even if they are full time 4wd (on some level). At this point many of the original Viscous Couplers have stiffened or locked up and then been removed so you have to factor in the original setup as well as any changes possibly made to ascertain if you have a VC in your truck.. etc.

The VC detects differences in speed between the front propeller/drive shaft and the rear propeller/drive shaft. In other words if the front wheels are spinning while the rear wheels have traction or vice versa then the VC detects this and locks/stiffens up to balance the delivery of power between the front and rear axles.

If you have a VC and have a taller/shorter tire front or rear then this could lead to the VC engaging to some degree all/most of the time. This will probably cause the VC to overheat and fail in short order.

I am not sure that a small fraction of an inch on one tire will matter but I know that an inch or so or more on one tire will matter. My 80 had a VC and mismatched tires when I bought it and the VC was locked solid due to overheating which I'm pretty sure was caused by the mismatched tires on the truck.

At the end of the day you need to keep your tire sizes as close as you can to avoid potentially burning up the VC in your truck if you have one and to avoid overworking/damaging your other differentials. New tires are probably cheaper than the possible towing, drivetrain parts and the repair labor in the long run.

If you try to figure out if your truck has a VC I think that the transfer cases that originally came with VCs are actually larger in that area to make room for them so that could be a clue among the many others. Testing by lifting some/all of your tires and spinning/etc. can also help you figure out what you have and how it's working. Beyond that researching your model, etc. should probably help you figure out what you should have at least.

 

[OREGON85]

I did this in a 1972 Chrysler Town and Country wagon and one rear tire 2" larger in diameter. At 100 MPH, the rear differential overheated and broke the pinion in half and started the rear axle gear oil on fire. This happened in 13 miles.

That sounds like an interesting story.

 

[BILT4ME]

That sounds like an interesting story.

Youth and ignorance.......

 

[musthave]

I might consider it to limp home off of a trail but that’s about it.

 

[MidMan]

@MidMan I'll try to explain the Viscous Coupler (VC) topic a bit

@jpoole thanks your details reply and very well noted.
If i am not wrong then i drove less then 50Km with these mis-matched tires and i never attained speed more than 60 km/h.

yesterday after searching the market for hours, finally i got relatively better condition 4-tires of equal size.
I will post a picture of them separately here.

 

[MidMan]

Good news is that i got the good condition Used Tires of BF Goodrich in size 265/70/R16
And bad news is that these were M/T.

Now the size is OK and i hope the differential will be feeling happy now
But its tread are very big, hard & strong. Hence at slow speed, i feel my seat is giving me "Massage" with lot of vibrations
Today i got its Wheel Balancing & Alignment. Will drive it at different high speeds and will check if everything is OK.

BTW, its sound is quite high as i could literally feel it inside the cabin

 

[MidMan]

My 99% traveling is on highways and within city.
last time when i visited workshop for Greasing the drive shaft, the person suggested me that he can remove the drive shaft from front differential and this vehicle will be all time RWD. And fuel average will also be increase like 25~30%

But i don't let me play with my jeep and asked him to just grease the shaft and don't do anything else.

Well, is it good idea to make this jeep from AWD to RWD ? Any pros & cons ?

 

[BILT4ME]

My 99% traveling is on highways and within city.
last time when i visited workshop for Greasing the drive shaft, the person suggested me that he can remove the drive shaft from front differential and this vehicle will be all time RWD. And fuel average will also be increase like 25~30%

But i don't let me play with my jeep and asked him to just grease the shaft and don't do anything else.

Well, is it good idea to make this jeep from AWD to RWD ? Any pros & cons ?

Doing that will NOT increase your gas mileage unless you also install locking hubs on the front wheels. Even then, you may only see minor increases in mileage. The pay back for the work in gas savings is years. Not worth it.

 

[renau001]

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Hi all, looking at the tread depth on all the tires of our new to us GX. Tires measure pretty evenly all around at 6/32". Spare measure at 9/32". Stock tread depth for the tire per tire rack is 10/32". So it appears that out of the 3 tire rotations the vehicle had, they only rotated the spare once.

So my question is is 3/32" or 2.5mm too much difference to go ahead and start rotating in the spare to even out wear? I'm concerned about uneven tire diameters and unnecessary wear on the driveline and differentials. Would appreciate your thoughts.