Question regarding varying tread depth between tires

[jasonkosi]

So long story short while on a road trip exploring remote backroads a rock put a fair size hole in my rear right, took to a tire shop unable to repair. My spare is full size matching (all 5 tires are 285/70R17 KO2s). The spare had no miles on it, my other 4 have close to 40,000km on them. The used tires clearly have less tread depth compared to the new one, have not had a chance to measure them accurately yet.

I’ve seen conflicting info online, my question is is it okay to run tires with varying tread depths as long as they’re the same/similar on each axle? Some sources say any AWD/4WD vehicle needs all 4 to be the same for tire circumference to be equal. Would any issues result from engaging 4wd with different tread depth (tire circumference) between front/rear axles? Ideally trying to avoid having to buy a whole new set of tires.

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[Escape Hatch]

I am also under the impression all four need to be within 2/16s of each other. Why didn't you do a 5 tire rotation? The decision not to will cost you.

 

[FaaWrenchBndr]

You will be fine, but DO NOT, use 4A or 4WD
The tire diameter will cause a driveline issue if you do.

 

[JohnTrigger]

Here is what your 2024 owner’s manual says about “mismatched tires”. Since Ford uses the word “significant difference” and still allows most things 4wd, according to how I read the manual in this section, you’ll be fine. Obviously it’s not ideal from common sense point of view.

https://www.fordservicecontent.com/...A&div=f&vFilteringEnabled=False&buildtype=web


That said, when using the full size dissimilar spare (not your case), it says this, so even Ford is somewhat contradictory (perhaps because the full size spare they provide is a relative POS tire, which is why I’m sure you changed it out):

https://www.fordservicecontent.com/...A&div=f&vFilteringEnabled=False&buildtype=web

 

[JohnTrigger]

A few more opinions here recently in this post:

https://www.f150gen14.com/forum/threads/issues-replacing-just-one-tire.38781/#post-661696

 

[miniceptor86]

I am also under the impression all four need to be within 2/16s of each other. Why didn't you do a 5 tire rotation? The decision not to will cost you.

5 tire rotation cost most likely would be more expensive at least in my case because the spare tire while the same as the other 4 was on a steel wheel requiring a dismount/mount and balancing.

 

[jasonkosi]

I am also under the impression all four need to be within 2/16s of each other. Why didn't you do a 5 tire rotation? The decision not to will cost you.

Only reason I didn’t is because the spare is mounted on a black steel wheel with no TPMS.

You will be fine, but DO NOT, use 4A or 4WD
The tire diameter will cause a driveline issue if you do.

I figured this was the case. I’m going to take it to another tire shop tomorrow morning now that I’m back home and see if they can shave the tread off the new tire to match the other 3. Otherwise I guess I just have to bite the bullet and get a new set of tires.

 

[JohnTrigger]

If you wanted a less costly solution what about this:

What if you bought just one exactly the same, call it tire “A“. Mount it in place of flat one. Rotate the tires if needed so you have a fresh start. Wherever tire A ends up, pull the semi used tire on that same axle‘s opposite side, and mount it as the spare on the steel rim. Mount the present unused spare on in its place on your nice rim. Then you have two full tread tires on that one axle and two half used tires on the other axle, with a half used spare.

 

[jasonkosi]

If you wanted a less costly solution what about this:

What if you bought just one exactly the same, call it tire “A“. Mount it in place of flat one. Rotate the tires if needed so you have a fresh start. Wherever tire A ends up, pull the semi used tire on that same axle‘s opposite side, and mount it as the spare on the steel rim. Mount the present unused spare on in its place on your nice rim. Then you have two full tread tires on that one axle and two half used tires on the other axle, with a half used spare.

I was thinking of doing this, as luck would have it somebody has a single new tire in the exact same spec and size as mine for sale on marketplace locally. The issue as was mentioned previously is when engaging/using 4wd with varying tread depths between front and rear axles which is what I’m most worried about.

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