• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Mixing tires of same size

4

420BlackXJ

NAXJA Forum User
Location
St. Paul, MN
I recently purchased 4 used Mastercraft Courser MT's 31x10.50x15's.
2 of them are in very good condition. They balanced using minimal weights, and have lots of tread left. They are on the front.
The 2 on the rear, are not in such good condition. Uneven wear, and not lots of tread left.
My question is this:
Can I mix 2 31x10.50x15 Kumho MT's for the rear, or should I go with the exact same tire as on the front?
I know I should not mix side to side, but can the rears be different brand from the front but the same size?
 
go for it....even if the two companys differ some. i would run them if needed just dont use 4 wheel drive on the pavement. 2% difference is actually acceptable due to the slop in the driveline as long as they are not on the same axle. probably the same size neway so run em hard
 
420BlackXJ said:
I recently purchased 4 used Mastercraft Courser MT's 31x10.50x15's.
2 of them are in very good condition. They balanced using minimal weights, and have lots of tread left. They are on the front.
The 2 on the rear, are not in such good condition. Uneven wear, and not lots of tread left.
My question is this:
Can I mix 2 31x10.50x15 Kumho MT's for the rear, or should I go with the exact same tire as on the front?
I know I should not mix side to side, but can the rears be different brand from the front but the same size?
Click to expand...
To answer your question...yes you can.
 
I would Physically compare the tires & Make sure they are close in size before using them. Just because they are marked the same size means nothing.
I saw 2 265X75X16s side by side in a tire shop, One a Perilli one a Chinese brand (I think it was Hankook) The Perilli was nearly 3/4 of an inch taller.

That kind of difference front/rear could cause lots of driveline stress when in 4X4.
 
I always mark the sidewall and floor with chalk, roll the tires one full turn, mark the floor and measure between the marks, matching up the closest tires with each other per axle, of course this is more important when running lockers.

There can be large variances in tires sizes, between manufacturers, and even the same size tire but different models from the same manufacturer can vary widely. The variances seem greater the larger the tire size.

I have no experience with the NP242, so I am just repeating what someone else posted that they had some trouble in full-time 4wd with mismatched tires.

Also, when running good/poor tires, put the poor tires in front. Check most any manufacturers website and you find that tidbit of info.
 
If you are worried about tape measure the circumference to see if they are any different. For the road, I do like to keep VERY similar tread patterns and wear on the same axle (side to side). Mostly for wet weather control.
 
joe_peters said:
I always mark the sidewall and floor with chalk, roll the tires one full turn, mark the floor and measure between the marks, matching up the closest tires with each other per axle, of course this is more important when running lockers.

There can be large variances in tires sizes, between manufacturers, and even the same size tire but different models from the same manufacturer can vary widely. The variances seem greater the larger the tire size.

I have no experience with the NP242, so I am just repeating what someone else posted that they had some trouble in full-time 4wd with mismatched tires.

Also, when running good/poor tires, put the poor tires in front. Check most any manufacturers website and you find that tidbit of info.
Click to expand...

I put the good tires up front, because I didn't want to deal with the vibration in the steering caused by the uneven wear, and the possible pulling to one side of the two I put on the rear. Of course, I only use 4wd on slippery/gravelly/wet surfaces.
 
I don't see why it would cause problems if you're only using 4WD on loose surfaces. How is it any different from STEERING on the loose surface? I don't see anybody advising people to only drive in a straight line offroad in 4WD
 
420BlackXJ said:
I put the good tires up front, because I didn't want to deal with the vibration in the steering caused by the uneven wear, and the possible pulling to one side of the two I put on the rear. Of course, I only use 4wd on slippery/gravelly/wet surfaces.
Click to expand...

Studies have shown conclusively that when your rear tires break loose you have no control, however, even with bald tires on the front you can regain control if they break loose through the steering, and that is why the manufacturers tell you to put the best tires on the rear.
 
winkosmosis said:
I don't see why it would cause problems if you're only using 4WD on loose surfaces. How is it any different from STEERING on the loose surface? I don't see anybody advising people to only drive in a straight line offroad in 4WD
Click to expand...

I was thinking the exact same thing, but a little re-enforcement of ideas is a good thing.:cheers:
 
joe_peters said:
Studies have shown conclusively that when your rear tires break loose you have no control, however, even with bald tires on the front you can regain control if they break loose through the steering, and that is why the manufacturers tell you to put the best tires on the rear.
Click to expand...

That makes sense. With that line of thinking, maybe I should put the new siped tires I'm gonna get on the rear.
 
That's why cars are tuned to understeer rather than oversteer. If you oversteer, you spin out, and in a Jeep, that could also mean roll. If you understeer, you have to tighten your line some and slow down. Much safer.
 
joe_peters said:
I always mark the sidewall and floor with chalk, roll the tires one full turn, mark the floor and measure between the marks, matching up the closest tires with each other per axle, of course this is more important when running lockers.

There can be large variances in tires sizes, between manufacturers, and even the same size tire but different models from the same manufacturer can vary widely. The variances seem greater the larger the tire size.

I have no experience with the NP242, so I am just repeating what someone else posted that they had some trouble in full-time 4wd with mismatched tires.

Also, when running good/poor tires, put the poor tires in front. Check most any manufacturers website and you find that tidbit of info.
Click to expand...

winterbeater said:
If you are worried about tape measure the circumference to see if they are any different. For the road, I do like to keep VERY similar tread patterns and wear on the same axle (side to side). Mostly for wet weather control.
Click to expand...

Both great points, but rolling diameter is going to matter more than unloaded diameter. Put all the tires on, find the flattest surface you can, park on it, and measure center of hub to ground at each wheel. Add or remove air till they're as close as you can get them... without screwing up your tread contact pattern unduly. You're likely going to have to make some compromises.

Obviously this matters way more side to side than it does front to back. I thought the bearings in my MJ's d35 were shot (well, they are, but not as badly as I thought... who cares it's a d35 :dunno:) and it turned out to be that my rear right tire was nearly bald and leaking air badly, so it was a good half inch lower than the rear left. On the highway you could really hear the shafts against the carrier and the spider/side gears at work, it wasn't a pleasant sound.
 
kastein said:
Both great points, but rolling diameter is going to matter more than unloaded diameter. Put all the tires on, find the flattest surface you can, park on it, and measure center of hub to ground at each wheel. Add or remove air till they're as close as you can get them... without screwing up your tread contact pattern unduly. You're likely going to have to make some compromises.

Obviously this matters way more side to side than it does front to back. I thought the bearings in my MJ's d35 were shot (well, they are, but not as badly as I thought... who cares it's a d35 :dunno:) and it turned out to be that my rear right tire was nearly bald and leaking air badly, so it was a good half inch lower than the rear left. On the highway you could really hear the shafts against the carrier and the spider/side gears at work, it wasn't a pleasant sound.
Click to expand...

I always roll the tires, measure the distance, match the tires as close as possible on all four (or two), then I use the chalk-across-the-tread method to set inflation with the vehicle loaded and fueled as close to "normal operation" as possible. Anyone with an auto locker or LSD needs to make sure that both the tire size and inflation are the as close as is practical side-to-side, as you pointed out.

My tire dealer here in town accepts me the way I am--after 25 years--and his only issue is that I use masking tape to mark the sidewall and floor when rolling tires.
 
Arround here it is very common to run a bogger in the rear and tsl up front. You can do it but you need to make sure the tires are close in size like the others have said.
 
You must log in or register to reply here.

Similar threads

R
Is 2wd upper control arm mount(on axle)the same on both sides?
Replies
7
Views
2K
Rallyrs
R
B
1990 turn and parking light issue left front and dash
Replies
13
Views
658
RCP Phx
R
1
35x12.50r17 trail tires.
Replies
0
Views
193
1-tonxj
1
X
My brakes are crap
Replies
12
Views
3K
xjklmnop69
X
R
2wd beam axle mount question
Replies
0
Views
23
Rallyrs
R
Back
Top