have a set of 31's that measure close to 32" the 32's aren't any where near 32" tall.

what's the difference in running 2 tires of dif height, and still close to 31" tall ?

is it just the speed at which both tires are spinning or what ?

ex: my 31x15.5 are slightly less then 32" at the top of the lugs. and the trail busters dont measure anythere near 32. more like 31 1/2

trail buster are not shown in this pic. test fitting the rears

 

here's one with a mounted 33x15.5 & unmounted 15.5

 

these tires wont ever see the pavement

 

The rim size also makes a difference in terms of tire height. The only way to be sure is to out it on the rim then compare them.
If you're in the loose dirt or mud all the time, the tires will slip so you'll be fine. but if it's hard dirt......idk..

 

the ground is like a mix of hard and loose. but it's rutted out, lotta sandy area's with mud and bogs

 

current size for the rears are 15x12 if i could find another matching one i'd just run all 4. just can't justify paying 200$ for a new wheel that doesn't even match the other 3

 

don't run diferent size tires on a 4wd period. you risk driveline damage.

 

even with the front drive line disconnected?
i can get away with the rears on the pavement it's only 12miles to the park. I did find NTW's procomp 15x12 for about 118$ shipped. but shouldn't it be the same if i ran the 15.5's in the back with a 12.50 up front on a stock 15x8 ?

 

idk i think you would be ok on acceleration on dirt, but what about decell? and idling around? i just would not want to take a chance. maybe a little more research on tire size/air pressure. remember what you have to be concerned with is tire circumference.
in other words, measure around the outside of the tires and match them up with air pressure? or whatever it takes to get them close and i would think you should be good.
btw you should not not have to drop driveshaft if your not locked in.
that said i guess for trail only you might be ok, maybe someone that has run different size tires can give there opinion.

 

Just ready to get back out, with the new tires. only problem i have is i'm missing the 4th 15x12 but have all 4 trac tires. think i'll just order the procomp 15x12 for 118$ shipped and just run all 4 tires. just switch wheels when i get near the park. instead of trying to figure out what i can run up front.

 

i'd rather be safe than sorry.
wheel on...

 

The height of the tire is somewhat irrelevant when talking about 4wd on our trucks. What matters most is the circumference of the tire. Think about it, you can let the air out of a 32" tire so it's 31" tall, but the tread is still pretty much the same circumference either way.

So if one tire goes 10 feet in one revolution and the other tire goes 9'11", that's an inch difference in how far each tire wants to go in one revolution. 100 revolutions, and you're talking over 8 feet difference... and that difference binds gears and u-joints and can break them since our trucks run the front and rear axle at 1:1 ratio.

 

It's no different than how many older American trucks run a slightly different gear ratio in the front axle vs. the rear, as long as they're close, and you're not using 4wd on pavement, you'll probably never know the difference.

 

i ran 410s in the front and 390s in the rear in 4wd.. in mud its fine.. if your tires are as pretty close its like have bald tires in the rear and new tires up front.. you wont notice it. unless on pavement which as you said those tires will never see, and if they did throw it in 2wd.

 

It is totally relevant in that it needs to be the same on all 4 tires.
Tire height impacts circumference IMO...direct correlation

 

If you have Brand A on the front and the rear has Brand B and they are the same size on both brands, even this has caused a 4 wheel drive to bind up. Each manufacturer has their own standards. It will work fine as long as you dont engage the transfer case.

I wouldnt even try doing what you are thinking about, you would risk driveline damage. That is the downside of owning a 4 wheel drive is you get to buy all 4 tires at the same time. I wont even have a bald set and a new set on each end of the same brand for my self. One reason tire rotation is so important to me, just to keep them the same size.

Next time you are in your favorite tire store, measure a BFG 31 inch tire and a Michelin 31 inch tire. It will be close, but not the same, and this can cause issues. I learned the hardway.

 

you better put these tires on. it would be so sick

 

if you only engage the trasfer case on dirt, gravel ect you'll be fine. on pavement would be a bad idea though