Two or Four New Tires? (Center Diff Question)

[4boer2]

The thread title basically explains my question. I had two tires blow out Sunday night and I was wondering if I should replace all four or just two (on the same axel). Why couldn't I just replace two, as the manual says "replace in sets." Is it something with the diff? If so, please explain. However, the old tires do have 40K+ on them, so I have to take that into consideration.

Thanks

 

[Gatafly]

I would replace all four if it was me unless the other two and barely have any wear. The reason the manual says that, and I agree, is that as tires wear they obviously get smaller. Smaller tires spin faster so it can cause added stress and wear on your transfer case for those that have full time 4wd and you have two sets of two spinning slightly different speeds. There is not that much difference, but it does exist and I would not mess with it.

 

[jspagna1]

With 40K+ I would replace all four. You will have to soon anyways and you may get a better deal if you buy all four.

 

[SUP3RJEFF]

I agree, all 4 seems to be the smart/safe choice.

 

[4boer2]

I would replace all four if it was me unless the other two and barely have any wear. The reason the manual says that, and I agree, is that as tires wear they obviously get smaller. Smaller tires spin faster so it can cause added stress and wear on your transfer case for those that have full time 4wd and you have two sets of two spinning slightly different speeds. There is not that much difference, but it does exist and I would not mess with it.

Thanks, I have been trying to get a better idea on how it affects the center diff. Still kind of confused. If I have 4 new tires what does the transfer case do? And how is this different from what the trans case does if I have two different same size?

I'm still looking for that 'ah' moment of understanding.

 

[4RunnerFan]

Just another thought... I include my spare in every 5k mile tire rotation. Mine also has over 40k on the odometer, so when I replace the tires I'm doing all five of 'em.

 

[bytemaster0]

The thread title basically explains my question. I had two tires blow out Sunday night and I was wondering if I should replace all four or just two (on the same axel). Why couldn't I just replace two, as the manual says "replace in sets." Is it something with the diff? If so, please explain. However, the old tires do have 40K+ on them, so I have to take that into consideration.

Thanks

ABS and VSC require your tire sizes to be identical. Tires that have different wear levels will be of different sizes, naturally, as the tire wears. For the sake of safety, replace in sets! You don't want the ABS and VSC computers to miscalculate because it thinks conditions such as wheel slip and speed are different than they really are!

 

[Gatafly]

Thanks, I have been trying to get a better idea on how it affects the center diff. Still kind of confused. If I have 4 new tires what does the transfer case do? And how is this different from what the trans case does if I have two different same size?

I'm still looking for that 'ah' moment of understanding.

If your front tires have 40k and your rear tires are new then your front tirs are slightly smaller in diameter than the rear. The front tires will have to spin slightly faster than the rear. This means that the front driveshaft going into the tfr case is spinning faster than the rear driveshaft. May not sound like that big of a deal since they are different when making turns, but it does add wear since it is constantly occuring. As mentioned above, it will affect your vsc also I would imagine.