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nichole43 · 12-02-2009, 04:59 PM

so i heard that if you don't change all four tires together that it messes with your transmission case. i have never heard of this before but if this is true it can mean the difference between paying to get my gasket replaced or getting it done by the guy who sold me my truck.
is this just a line tire guys tell you to get a bigger sale or is this an actual problem?

xjman4life · 12-02-2009, 05:03 PM

In my opinion its bull ****. As long as they are the same size all around, you'll be fine. You might have abnormal wear because of different tread heights but if you didn't care already..what does it matter? Hopefully someone can chime in with more details, or thoughts.

89xj4.7 · 12-02-2009, 05:04 PM

i dont see how.. lol..... i mean you dont wanna run a 33 inch tires on front/rear with a stock tire on front/rear if you have 4wheel drive...... if you have a posi, running one tire smaller or bigger on one side can burn the diff clutches up........................

if i was you id go to the guy that told you this and give him a good swift kick in the... well, you know.

xjman4life · 12-02-2009, 05:04 PM

Explain more on the "gasket replace"??

BACKWOOD · 12-02-2009, 05:13 PM

He is talking about the transfer case. If your tires have a drastic differance in size from front to back it is bad for the transfer case "when in 4-wheel Drive". Your transfercase spins the front and rear axle at the same speed, but if your tires are different sizes "front to back" the tires will want to spin at different speeds to make a single revolution. This would put too much stress and more than likely explode your transfer case.

BACKWOOD · 12-02-2009, 05:17 PM

If your tires are all the same size, he may be talking about you having uneven treadwear. This would not be a serious issue to your transmission or transfercase though...

**WJCraig** · 12-02-2009, 06:17 PM

Different size tires = Bad

Different Tires of the same OD = OK

**2000XJ** · 12-02-2009, 09:31 PM

Quote:

Originally Posted by BACKWOOD

He is talking about the transfer case. If your tires have a drastic differance in size from front to back it is bad for the transfer case "when in 4-wheel Drive". Your transfercase spins the front and rear axle at the same speed, but if your tires are different sizes "front to back" the tires will want to spin at different speeds to make a single revolution. This would put too much stress and more than likely explode your transfer case.

Right on

In addition, two tires on one axle should always be the same size. Furthermore, if you're going to be using 4 wheel drive, all four tires should always be the same size otherwise your tcase will bind up and you'll damage it.

nichole43 · 12-03-2009, 12:57 PM

haha thanks guys, i thought it was odd that he said transmission case and i even called back to double check, apparently he is misinformed as well and i'll make sure to tell him its the transfer not transmission haha and the tires themselves are all the same size, the tread is just worn differently

and for xjman4life....my gasket is loose and is leaking slightly and i've always had trouble with transmissions on every car i've owned and they are not my strong suit

nichole43 · 12-03-2009, 01:00 PM

Quote:

Originally Posted by BACKWOOD

If your tires are all the same size, he may be talking about you having uneven treadwear. This would not be a serious issue to your transmission or transfercase though...

since the transfer case is connected to the transmission, even though you said it wouldn't be a serious issue, could it possibly be the cause of a loose gasket

**WJCraig** · 12-03-2009, 01:36 PM

Quote:

Originally Posted by nichole43

since the transfer case is connected to the transmission, even though you said it wouldn't be a serious issue, could it possibly be the cause of a loose gasket

No. I fail to see how tread can effect the transmission in any significant way.

Size, yes.

Tread design, pattern or wear...not so much. (Although, treadwear can be an indicator of other problems/worn parts)

Later.

88fadedglory · 12-03-2009, 03:55 PM

Different size tires will affect the wear on limited slip differentials (Trac-lok, Posi-trac, Sure-trac, Sure-grip, Eaton, Dana and locker styles) but not on open differentials. Simple logic: there is nothing but gears running in lubricant in open diffs, so they're doing what they are designed to do: allow axles to turn at different speeds.

On T-cases: if you do not have a full time 4X4 position on your T-case shift, you have to run equal diameter tires front and rear. Even then, if you shift to 4Hi,, you need the same size tires.

So, in reality, you need four tires of the same diameter on any 4X4 rig unless you adjust axle ratios to compensate. ( how do you think 4X4 farm tractors run small diameter tires oin the front??? different final drive ratios).

My suggestion: keep your tires rotated front to back to keep them the same size as the other axle until time to replace any single tire, then replace as a set.

BTW, loose trans gasket, assuming you mean the pan gasket, is from shoddy workmanship. It wasn't installed properly, either too loose or too tight of torque on the bolts.

4.3L XJ · 12-03-2009, 04:27 PM

Quote:

Originally Posted by nichole43

since the transfer case is connected to the transmission, even though you said it wouldn't be a serious issue, could it possibly be the cause of a loose gasket

Gaskets can seep a little with age, or leak a lot if what is holding the down becomes loose. If that is the case, just tightening the bolts on that piece will likely fix the problem. Also, if the guy thinks he needs to replace the gasket, it is better to use silicone rubber in place of the gasket. That stuff will never leak and is becoming the stuff of choice for transfer case manufacturers.

**mcatald** · 12-04-2009, 02:38 PM

Heres a case of know what you are talking about before giving advice!

Just because you have 4 tires that are the same size (i.e. 31x10.50x15) does not mean they have the same outside diameter, significant differences in tread depth will create a large difference in outside diameter.

Now on a vehicle that is not full time 4 wheel drive this is not a huge issue.
If you have a Grand Cherokee that is full time four wheel drive (quadratrac)
this is a real problem. The tires will rotate at different speeds and cause binding eventually destroying the viscous coupling.

So basically the tire guy is correct in recomending replacing all 4 tires at once.

BACKWOOD · 12-04-2009, 05:08 PM

Quote:

Originally Posted by mcatald

Heres a case of know what you are talking about before giving advice!

Just because you have 4 tires that are the same size (i.e. 31x10.50x15) does not mean they have the same outside diameter, significant differences in tread depth will create a large difference in outside diameter.

Now on a vehicle that is not full time 4 wheel drive this is not a huge issue.
If you have a Grand Cherokee that is full time four wheel drive (quadratrac)
this is a real problem. The tires will rotate at different speeds and cause binding eventually destroying the viscous coupling.

So basically the tire guy is correct in recomending replacing all 4 tires at once.

If you have full time 4wheel drive, how possible is it that you would have extreme enough differences in your tire size by treadwear. Unless if you drove forever with bad alighnment or inadiquite tire pressures. Nichole how bad is your treadwear, are they that noticeably different?