Mismatched spare issues?

Just stop every 50 miles and swap the tires

 

Open diffs will just work the spider gears more with mismatched tire circumference. Think about donut spares. Those are grossly mismatched and the manufacturers won’t void your warrantee if you use one.

 

I would most definitely have the odd size on the front, I wouldn't take the chance of blowing my rear end up from mis matched tires but that's just me

 

I think it’s a matter of picking your poison....I’d prioritize steering control over accelerated rear diff wear, put the mismatched spare in the back and steer with two good tires.

What I should really do is have different winter and summer spares haha

 

You can get the Cooper Discoverer M+S (cheap and very good snow tire that is studdable) or Nokian Hakka LT2 in 285/75/16, which is a 32.83" tire. Probably the closest you can get to a 33 in a dedicated snow.

 

I was agreeing with your posts. Dunno if I was clear enough, sorry.

 

That's not true. An open diff means each side can spin at different rates there would be Zero binding in 2wd

 

Yeah those Hakkas are on my short list, but I’d like to stick with the 255s if I can. Too bad they don’t make one.

Might end up being the push I need to go 35s haha

 

I've run a spare on the front of a FWD car. Have you ever tried to swap tires front to back with a single OEM jack? Yikes...

Let alone a truck probably with a lift and bigger tires, using a hilift or something, definitely not fun.

 

Does anyone actually know how things work?


DIFFERENTIAL
https://en.m.wikipedia.org/wiki/Differential_(mechanical_device)

Look at any front axle with a CAD (central axle disconnect). One stub shaft is always connected to one wheel and to one side of the diff. The other side goes to the disconnected shaft with the front driveshaft to the pinion. Since the front driveshaft is heavier and has more resistant to turning than the intermediate shaft the DS stays stationary and intermediate shaft turns. This results in the spider gears turning non stop when in 2wd. This is the same gears that turn when one tire is a different circumference than the other. For a short period like when you are running a spare there should be ZERO appreciable wear in the grand scheme of things.

OP - I agree with you keeping the same sized tires on the steering axles. I will stress that a different sized spare should be used ONLY to get you to a safe place like off the highway or a SHORT distance like home or a repair shop. I would never suggest that long trips be done while a different sized spare on. Even donut spares say max speed and distance on them for a reason.

 

You don't do them at the same time, lol. Thats a good way to get crushed!

Take good tire off first and replace it with spare/donut. Lower car, jack up bad tire, replace with the good one.

I also feel most donuts now are full height, probably for this reason. I haven't seen a new car with a noticeably shorter tire, just WAY narrower. You guys seeing shorter ones still? My wife's Cruz doesn't even have a spare... Came with air compressor with a jug of slime...

 

That would be like a 500’ circle for the same 3% ratio

 

Open diff doesn’t care, it just thinks you are doing a slight, continuous turn toward the smaller tire. When you are locked the scrub anyway at any turn. Not a problem. A mechanical LSD would care, eventually.

 

I agree, this is temporary. Just happened to be far from home. As soon as I can get all 4 tires matching again, they will be

 

A full sized spare tire (or one with the same OD) is a lot cheaper then potential problems that mismatched height can cause...

 

And hindsight is 20/20!

I’ll be on Craigslist this weekend....

 

Anyone know of a cheap rim to run at 285 on for correct offset? I don’t want to buy another Ray 10 to sit and get eaten up under the truck?

 

Saying running a 1” smaller diameter tire will ruin your diff is like saying turning a corner will ruin your diff. No issue at all in 2WD and would not make any difference on a loose surface in 4WD.

Where I live there is literally not a single straight road of any length. My diffs spiders are always spinning to some degree, all the time. Guess my truck is fuckered. Dealer said “warranty void / too much time spent steering”

 

Matching spares are cool but there’s a lot of over thinking going on in this thread. You will not damage your diff running a smaller tire to the closest tire shop.