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Mixed tire sizes on truck

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November 23, 2022, 11:45 AM
Chris42
Mixed tire sizes on truck
All of the above makes sense.

All of the above is reasonable and true in the academic/theoretical discussion.

All intent with the discussion is to minimize excessive stress or wear on the spider in the differential. The limited slip feature helps with this.

Now in the nitty-gritty real world -
If the above were the primary concern, and yet there was some need for running the odd tire over an extended period of time, there is an easy way to minimize that internal wear -
Measure the radius of all your tires. On a level, solid surface measure Axle center to the ground. Adjust pressure to be correct in the three “good” ones. Adjust pressure in the odd tire so the radius on all tires is the same.
This will minimize internal wear on both front and rear differentials. It will also cause MORE wear on the odd tire (this being the cheapest thing to repair/replace). It may also affect steering (pulling while braking in a turn) so it is good to be aware of and prepared for that likelihood.
November 23, 2022, 04:33 PM
4MUL8R
I formulated rear axle lubricants for limited slip axles. Different size tires on tbe rear axle were how I performed accelerated durability tests on the clutches and lubricants. It would be detrimental to either axle to have different size tires. It would be continuous clutch slip on any axle with a limited slip clutch system. This will degrade the clutch surface irreversibly.

Your tire size difference is small, compared to my durability test axles. But continuous clutch slip is not good.


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Trying to simplify my life...
November 23, 2022, 05:56 PM
walker77
The truck is a 2018 Nissan Titan XD. And it came with General Grabber HTS.

I was a little pissed when the shop replaced it because they never told me that insurance approved the tire replacement. I was going to switch to something different. The Generals were suppose to be 40k tires. I had to really stretch it to get 30k out of that set.

They put that size tire on there because it was cheaper. I know because I've been pricing tires to put on it. I almost went with that size to save money. I had the new tires put on last Friday. I found this wrong sized tire when I was making sure all the tires were aired up the same.


November 23, 2022, 07:36 PM
reflex/deflex 64
Is the OD of the replacement closer to the OD of the worn tires than that of a new one?. Even if the above were true it’s wrong. Be like telling you the paint while being the wrong color is still a shade of red.


----------The weather is here I wish you were beautiful----------
November 23, 2022, 08:50 PM
walker77
quote:
Originally posted by reflex/deflex 64:
Is the OD of the replacement closer to the OD of the worn tires than that of a new one?. Even if the above were true it’s wrong. Be like telling you the paint while being the wrong color is still a shade of red.


Huh?

The tire the body shop put on is a General Grabber HTS60 275/60 R20

The tires I had put on last week is exactly the same as the ones that came with it from the factory. General Grabber HTS 265/60 R20. I ordered the size based off the door sticker.
November 24, 2022, 05:44 AM
egregore
No good, in the long term, ever comes from mismatched tires on any vehicle. But you aren't that bad off in the short term. No 4wd I know of has LSD front axles. Also, in many 4wd designs (not sure about yours), the front diff axle shafts are uncoupled unless 4wd is being used, and that in turn is for conditions of slippage, never dry pavement. So no worries about front axle wear or damage. What mismatched tires on the front will do is cause the truck to drift or pull to the side with the smaller diameter tire. Not dangerous or you wouldn't be still with us, but you still have to correct for it. On a rear LSD, mismatched tires are detrimental. Just put the blasted right size tire(s) on it already.