Mismatched spare issues?

Update:
TL;DR: how dangerous / detrimental to the diff is it to run a spare that's a different size to the other 3 tires?
Answer: it's better to have a same-diameter spare if you can help it, but if it'll just be for a short distance then you'll be fine with a close-sized spare since these trucks have pretty robust open rear diffs.

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Here's my current tire situation:

Current Tire: 267/75/16 Blizzak DM-V2s (32")
Current Spare: OEM 265/70/16 Goodyear Wrangler (31")
Planned Summer tires: 255/85/16 Cooper ST Maxx (33")
Planned new spare: 255/85/16 Cooper ST Maxx (33")

My issue is that snow tires (Blizzaks and Hakkas anyway) don't come in 255/85/16 (or even 255/80/17) and I don't want to deal with 285s / CMC / hammering blah blah blah.

Got a question for TW....how dangerous / detrimental to the diff is it to run a different sized spare? Assuming I don't change my mind and continue on with the 33" ST Maxx plan next month, I'll have the opposite (same?) problem next winter (33" spare ready to go while the 32" Blizzaks are back on).

I'm thinking that it'll be more of an issue for the wrong-sized spare than for anything else. I'm betting that it'll wear in <5k miles or something.

I think the rear diff will be ok since it's open and I'll be turning off traction control. Don't need the truck going bonkers because the wheels are spinning at different rates.

Ask me why I thought of this in the middle of the day on a Wednesday....

 

Discount Tire just told me that it's unrepairable but they can prorate me for a new tire, so that's not the end of the world, but they'll have to order the new tire in

The truck is already pulling to the right a little (small spare is on the rear right).....

 

You could always swap a front to the rear and put the spare on the front in the event of a rear flat.

Then again I am no mechanic and have most likely overlooked something here.

 

From what I understand it's not good. When I went from stocks to Micheleins 265/75/16 my mechanic said I had to change the spare.

 

Definitely don't want to do that......you're always better off putting the spare in the rear since the front tires are the steering tires (unless it's a matching full sized spare, in which case it's all good)

Yeah I can't imagine it's a good thing.....makes me reconsider the 33" game plan......

 

My mistake

 

it's all good......I learned that one the hard way on my Subaru.....

 

It is not your diff that is the problem. It is the binding that you will get if using 4wd.

I am planning to go from 265/65R17 to 265/70R17 and keep the stock spare, which is a Firestone Destination compared to the Toyos that were at each corner. I've rationalized it that if I have damage larger than I can plug, my day of fun will be over and I will just get out and use 2Hi as much as possible.

Just like the typical 4wd stuff, if on a slick / low-friction surface it won't hurt anything. But, unlike typical 4wd, driving straight on wet or dry pavement will start to bind the system. That is the only real concern.

 

I agree with that, I won't be using 4wd while the tires aren't all the same size.

wonder if this will affect the Accumulator Delete Mod......lol NOPE still doing that first chance I get

 

Ha! Get that PoS outta there!

 

If you drove in a huge circle for hours, would it be harmful to the diff? Same as having a different size tire on one side.
I say no, it’s not a problem, but what the fuck do I know...I’m just some guy on the internet.

 

haha I was thinking that too.......are nascar tires the same on both sides?

 

Same.

I keep putting the delete off.. need to just get it done

 

Nope. It is even more pronounced on sprint cars, and I believe they are running a posi rear on the dirt.

 

Its not a mistake

Its smart and what I would do to save my diff...

Slow down, and put the little tire on the free hubs in the front..

And if you feel it isn't safe, just get a cheap spare the size you need, it doesn have to match..

 

but if my rear diff is open (no limited slip, no fake limited slip with the brakes since I've got traction 100% off) then isn't it better to have the spare on the rear?

 

not really..

Its still binding the gears within the diff housing...

Open diffs still need the right size tires..

 

the good thing though..

The tire that will shred will be the smaller tire because it is easier to turn....

So your fancy tire will be ok on the other side..

lol...

 

if not using 4wd it is fine

open diff doesn't bind anything with odd size tires. one size can have different rotational speed with zero problems, that is what diffs do.

if using 4wd make sure you have slippery conditions so transfer case takes less of a beating

if the difference is major (like, a lot) vsc may actually try to kick in as it senses speed difference between wheels

 

Haha silver lining