V8 full time 4wd

[kai920]

Can anyone tell me, on the V8 4th Gen, if a tire needs replaced do all tires have to be replaced and match exactly to prevent any binding or damage to the transfer case? Looking at buying a V* with all time 4wd, but the guy has two newer tires on it and two older. He said he's had it that way for about two months. Any issues with t-case here?

Also, has anyone had a leaking o-ring between the transfer case and actuator? Toyota quoted me $900 to replace an o-ring because they said the t-case had to be removed, same labor as replacing the t-case? Sound about right?

 

[Paul_R_Canada]

I can't see same size tires with different wear being any issue, different sized tires maybe would stress the system, but not same size. If it was that sensitive it woudl not last offroad for long.

Can't help you with the tcase leak

 

[kai920]

Makes sense to me, but I've been told otherwise by a mechanical engineer. But hes not a 4runner owner either. He did have a jeep with full time 4wd and said that system was not at all forgiving and neither is subaru, that its a bad idea to have different tires.

He did admit he knows little about the 4runner system though.

 

[highspeed]

I asked the same question not long ago after I took a nail in one sidewall. The concensous was to keep the two tires on one differential the same.
I was told that even the same tires but 30,000 mile difference in wear is enough to cause damage to the differential. I think highway speeds have a lot to do with it...

Anyways, I'm running my old set on the rear, about 30k mi on them - and my new set on the front, about 8k mi on them now. No problems so far. I will make sure they rotate the pairs.

 

[JCR]

If you are worried about it then get a new set. Personally, I wouldn't drive a vehicle with mismatched tires if I didn't have to, just because it would bug me when I looked at it. If they are the same size I doubt it will hurt.

I have no idea about the o-ring. Take it to somewhere other than the dealer and have them give you a quote.

 

[CJ3Flyr]

I can't see same size tires with different wear being any issue, different sized tires maybe would stress the system, but not same size. If it was that sensitive it woudl not last offroad for long.

:iagree:

Makes sense to me, but I've been told otherwise by a mechanical engineer. But hes not a 4runner owner either. He did have a jeep with full time 4wd and said that system was not at all forgiving and neither is subaru, that its a bad idea to have different tires.

He did admit he knows little about the 4runner system though.

Yes, i agree that the Subi, Honda and other AWD's can be very sensitive. The 4Runners full time system is less sensitive. Why? 1) It's a full-time, geared differential, no clutch mechanism. 2) The system is already more biased than a slight difference of the same tire with different wear (from the factory)! It sends about 40% of the torque to the front and 60% to the back with a wide range of variation to be used as needed.

Think about... Even 4 new tires are slightly different. If all tires are inflated to 32psi the fronts are shorter due to the extra weight of the engine. To be perfect you'd have to run 34-35psi in the front and 32 in the rear.

What is my advice if you're worried about it and can't sleep due to the minor difference in diameter? New(er) tires on the front. That helps with hydroplaning and gives you a scenario where all 4 tires are as close to the same diameter as you'll ever see.

I asked the same question not long ago after I took a nail in one sidewall. The concensous was to keep the two tires on one differential the same.
I was told that even the same tires but 30,000 mile difference in wear is enough to cause damage to the differential. I think highway speeds have a lot to do with it...

Anyways, I'm running my old set on the rear, about 30k mi on them - and my new set on the front, about 8k mi on them now. No problems so far. I will make sure they rotate the pairs.

Sounds about right to me... It's good practice to keep matching tires on each axle.
:cheers: