This morning I was looking at the back end of my Cherokee, which I purchased used a few months back, and noticed that one tire seemed to be wider than the other. So, I decided to investigate further. Sure enough, the passenger side has 225/70-15 F&R and the drivers side has 225-75-15 F&R. That can't be good for anything in the driveline. That probably explains why it pulls slightly to the right. The tires are the same brand/model and appear to be the same age and have a significant amount of tread.

My question is, other than replacing them, which size should I run on the front and rear considering that I plan to do some 4wd on icy roads next winter? My first inclination is to put the 70s on the front and the 75s on the rear thinking that the lighter rear end will have tendency to slip sooner on icy surfaces and thereby minimize the size difference front to rear. On second thought, it is possible that it could give it a tendency to swap ends if the conditions were right. What would you do? Any opinions?

 

You need to get 2 new tires.Put the smaller ones on the front for now.Don't use 4wd til you get the same size tires all around.You can damage the transfer case.Your axles are both geared the same.If you have differnt sized tires on it then it will change the gear ratio on the axle with bigger tires.You don't want to run different gears on the same Jeep.

 

Thanks for your thought, while I agree that running on a dry trail in 4wd would be ill advised, my main concern is with icy roads. The size difference is minimal, and I believe that in icy/slippery conditions, there is little risk of driveline damage. However, I would not want to run extensively in 4wd in any conditions. I plan to use 4wd occasionally for temporary icy conditions to get me through rough spots. I plan to change tires ultimately, but finances will not allow immediate change.

 

Oooops didn't finish reading all of the OP, never mind.

 

If the difs are open, I'd leave it. That way the differentials correct for the size and the transfer case doesn't have to.

 

You may be on to something here. I hadn't considered the diffs. I wonder how it will handle on ice-if there will be some sideways pulling or a tendency to drift to one direction?

 

It should still pull to the same side it's already pulling towards, but on ice or snow, even if you had ludicrously mis-matched tires, you still won't do any damage.

As long as you don't do what most soccer moms do and assume that because they're in a 4wd SUV that they can do the same speeds in the dry as on ice, you should be fine.

Personally, I would be morbidly annoyed that the vehicle pulled to one side, but I wouldn't expect to damage anything as long as I used my head and drove in a sane manner.