Mis-Matching Tire Sizes

[hodgepodge79]

I have a 1987 4Runner, 4x4.
What am I risking by using mis-matched tires.
Example: I have 31's on all four, with a 30" as a spare. If i have to put the spare on the rear axel in 2wd, is there a problem? What about on the front in 2wd? On the front or rear in 4wd?
I guess I am too cheap to buy a full-size spare.
Thanks for your help!

 

[AlexJet]

It all depends. I think if you will drive slow and carefully to nearest tire shop small mismatching shouldn't be a big problem. I'm also having 275/70 on wheels and 265/65 spare, and my tires cost $350 per tire and $200 per rim, which is $550 +tax.

 

[Thai]

If you have a flat (front or rear), then make sure that the mismatch spare goes to the front axle AND that you're in 2wd. Drive slowly.

 

[hodgepodge79]

As long as the mis-matched pair are on the non-drive axel (front) why couldn't I drive normal, i.e. 55mph? If there is no power to the front, the two cv shafts are completely independent, right? Couldn't I potentially drive with a 31'' on one side and a 225/70 on the other?
What damage, if any, could occur?

 

[Thai]

As long as the mis-matched pair are on the non-drive axel (front) why couldn't I drive normal, i.e. 55mph? If there is no power to the front, the two cv shafts are completely independent, right? Couldn't I potentially drive with a 31'' on one side and a 225/70 on the other?
What damage, if any, could occur?

Your steering and handling may be affected. So, it begs the question...why do you want to test your luck?? Your spare is for emergency situation, right? So, treat it as such!

 

[trd2001]

Fill the smaller tire to the max, and let the aire out of the bigger one. I did this once in my Tacoma, since i had 32's and my spare was a 31. I drove 50 miles this way home.

 

[hodgepodge79]

Your steering and handling may be affected. So, it begs the question...why do you want to test your luck??

Again,...What I really want to know, is, do I risk damaging the transfer case gears or differential gears by driving along with this set-up?
Obviously it will handle different, but is there a risk of driveline damage (with one undersized tire)?

 

[K6UK]

Smaller Spare

I have a full time 4WD V8 and I have the same question. I am thinking of 275s as my tire choice, but cannot fit one underneath. So until I get a tire carrier my spare must be -1 size.

I know this is not optimal, but will I damage anything? Obviously deflating the other tires a bit seems like a good idea.

Traction control could also be an issue, but I saw a post somewhere of what I would need to unplug to disable it in an emergency.

So - other than traction control - are we risking much by mounting a smaller spare on a driven axle?

thanks,

-Mike