How much difference in tire diameter does it take to harm rear diff?

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wopachop

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I heard it was bad for the rear differential if you do long straight highway drives with different size rear tires. Is that even true? Only with limited slip?

If true how much difference does it take? I need 1 new tire for a pickup truck. It turns out that if the current tires have worn 1/4" of tread, the new tire will travel 1.61" further for each tire revolution. 1/8" of tread gone equals 0.78" further. Seems like it could be significant? I think my tires are worn somewhere in between. Cooper AT3's. Front right got egg shaped, possibly after hitting a pothole. Theyve hit a bunch in their life so far. 10east out to G is rough at spots. 

 
What you should do, like I do If I have to use my spare on my truck (has 35's) is take the spare and put it on the front, and move the front tire to the rear.  this assumes that the bad tire is on the rear.  Then you need to use your road hazard warranty for both rear tires, so you end up with 2 new matching tires. 

 
HTElectrical said:
 Then you need to use your road hazard warranty for both rear tires, so you end up with 2 new matching tires. 
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How are you getting a warranty for both rears when only 1 tire is damaged? 

My used truck came with new tires a couple years ago. Went through all the paperwork hoping for a receipt and transferable warranty.

Will get the warranty with the new tires its $35 extra. 

 
Well, on my old tires they were Hankook Dynapro, and without fail at less than half life I would get an egg on one tire, while towing, and the stepped up 3 times, before replacing all 4 for a different tire.  The other way is to mysteriously get a side wall nail DOH...  Just kidding. (Maybe)

 
It’s simple just put the bigger tire on the right side and just do burnouts until it matches the other side.  :rotf:

 
MWB said:
Just buy a flipping tire you cheap bastard
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For sure its sitting in the discount tire cart now. Trying to decide between 1 or 2 tires. Not sure if buying 2 tires is a waste of money, or if buying 1 tire is being a cheap bastard. I like balance. The new tire can be close to 1/2" larger in diameter, and wonder if that is no bueno for the rear diff. 

 
I know 2 guys that blew their diffs doing this.

I'm not sure what the difference in size was but they were both limited slip.

 
HTElectrical said:
Well, on my old tires they were Hankook Dynapro, and without fail at less than half life I would get an egg on one tire, while towing, and the stepped up 3 times, before replacing all 4 for a different tire.  The other way is to mysteriously get a side wall nail DOH...  Just kidding. (Maybe)
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Sometimes picking up others burnt pallet trash can be of help it does a good thing getting nails out of dunes just be very careful not to drop around the house damn truck may run over one.

 
wopachop said:
For sure its sitting in the discount tire cart now. Trying to decide between 1 or 2 tires. Not sure if buying 2 tires is a waste of money, or if buying 1 tire is being a cheap bastard. I like balance. The new tire can be close to 1/2" larger in diameter, and wonder if that is no bueno for the rear diff. 
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I totally get this.  I didn’t go to glamis for an entire season because I broke a rear tire in dumont and couldn’t decide between finding a used tire, buying one new STU, buying 2 new STUs or buying 2 el-cheepo’s. Then one season turned into 2 and 2 seasons turned into 4 years and before I knew it I haven’t been in 6 years ..... I ended up just buying a new car..... and the very first thing I did was put 4 new STUs on it LOLOLOLOLOLOLOLOL

 
wopachop said:
For sure its sitting in the discount tire cart now. Trying to decide between 1 or 2 tires. Not sure if buying 2 tires is a waste of money, or if buying 1 tire is being a cheap bastard. I like balance. The new tire can be close to 1/2" larger in diameter, and wonder if that is no bueno for the rear diff. 
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Well in that case get a smaller new tire.

 Are you really that dense, Buy two flipping tires if a new tire is going to be /2" bigger than your worn out POS tire that your trying to convince yourself is still a good tire you truly are a special kind of stupid.  Replace both tires it's time and guess what brain surgeon if the other two are the same age well you might need to replace them as well because guess what they are worn out too. 

 
Heres to MWB. Taking the smart, out of smartass comments.

The other 3 tires are still in great shape.

 
Five.five-six said:
I totally get this.  I didn’t go to glamis for an entire season because I broke a rear tire in dumont and couldn’t decide between finding a used tire, buying one new STU, buying 2 new STUs or buying 2 el-cheepo’s. Then one season turned into 2 and 2 seasons turned into 4 years and before I knew it I haven’t been in 6 years ..... I ended up just buying a new car..... and the very first thing I did was put 4 new STUs on it LOLOLOLOLOLOLOLOL
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I hear ya. Was hoping the rear differential topic would sway me. Think im gonna go the cheap route and buy 1 tire. Run it up front and rotate the other 3 tires in some pattern that makes sense. Need to try and plan ahead and take advantage of memorial sales. They had my tire for buy 3 get 1 free. Will ask the tire guy if he knows how often that deal comes up. 

 
I had a tire come apart on my truck right at the ranger station one year. spare was a 265 and the ones on the truck were 285. thought Id be OK to get to pad 4. it scrubbed the all the tires that were 285 and looked like they were in the shredder in those couple miles up the road. just buy 4 new and be done.

 
Buy a whole set of used tires.  Done it twice before.  Really cheap option. 

 
wopachop said:
I hear ya. Was hoping the rear differential topic would sway me. Think im gonna go the cheap route and buy 1 tire. Run it up front and rotate the other 3 tires in some pattern that makes sense. Need to try and plan ahead and take advantage of memorial sales. They had my tire for buy 3 get 1 free. Will ask the tire guy if he knows how often that deal comes up. 
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You could also get that new tire shaved at an off road shop, if you can find one.  I know they used to have shops that would shave (true for roundness) the really big tires 40+ inches, because you can not spin balance tires that big.

 
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