im going on my first wheeling trip in which i will be far enough away from home that a spare tire is important. ive got 32" tires but only a 31" spare. anyone ever drive a couple hundred k on an undersized tire? any problems? keep in mind im open dif.

 

you would be fine

 

just a thought, if one of your front tires gets a flat, put one of the 32's from the rear on the front and put the spare on the rear.

at least make sure your spare has been balanced .

 

I've done that and driven 300+ miles like that. I have 31's on all 4, but I skidded off the road in the rain, and hit the bank on the side, and pushed my tire off bead. So I put my 225 spare on the back, and swapped out the bad one up front for the good one off the back. I was able to do some pretty decent burnouts for a while, though. So, No you'll be fine.

 

So when if you got 40's and got a 31" spare... ???

 

preflex?

 

I've run a 31" spare 200+ miles on the rear of an '86 4wd 4Runner before that had 32"s on the 3 remaining corners and it was fine.


I'd really like to know if there is a size limit when running smaller spares and if there is a limit what is it? Meaning could I run a 31" spare tire on a 4Runner w/ either a set of 33s, 35s, 37s or larger? Is there a point in which a smaller tire is too small to run in combo w/ larger tires?

 

I am glad I found this thread, because I thought it would be better to run the smaller tire up front. Can someone give a quick FYI on why it is better to have mismatch's on the rear?

 

Well, we've all seen those ridiculously small inflatable spare tires that are so small that the vehicle lists heavily to one side. So manufacturers aren't too worried about problems cropping up but I'm sure the owners manuals are plastered with warnings about driving slow and fixing the flat tire ASAP. For an SUV, a large spare tire mismatch becomes a bit more of an issue due to an increased tendency for vehicle roll over. Also, differentials and full-time t-cases aren't too happy with large tire differences either. Heavy braking will probably result in quite a pull to the side with the small wheel (especially if it is on the front).

Bottom line is you can get away with just about any tire size mismatch as long as you drive slow and don't travel hundreds of miles.

 

As long as you don't have a locker on the axle that has a flat it isn't a big deal. The diameter on locker equipped axles has to be the same as the each tire will be given the same amount of revolutions - it would steer the vehicle and you'd have a hard time keeping it straight.

I'm in a worse boat. I have 32's and lockers front and rear. Doh!