Narrow tires would have more pressure per square inch on the ground so better grip and less tire slippage, right? But wider tires have a larger contact patch, so wouldn't that also mean better grip? Can someone explain this a little better? I would usually drive on the road most of the time while driving on dirt roads that sometimes have snow to go hiking. Which tire be better for my driving, and why?

 

surface area wins. dirt / tire area are an important factor. how much traction if your tires have knife edge width?

 

The XJ has relatively narrow wheel wells and wide tires tend to rub. A stock XJ can take a 235. My 3" lifted '99 has 245's . Note that airing down increases the contact patch - but should be reserved for slow speeds and off-road

 

my tires are 12 inches wide, 33 inches in diameter. traction is pretty good, specially at 12 psi pressure. Id hate the traction of a skinny bicycle tire on my jeep, but that is me.

 

Indeed, with a 4-1/2"+ lift that can be done and I drought there are very many people still driving the 215's that Chrysler placed on them when new. Often people trim the finders to get larger tires to work to, but it also depends on where you wheel your jeep. Fortunately, the XJ is relatively small and light and my 9.7" wide BFG KO2's (aired down to 20psi) provide more than adequate traction to climb hills on the 4x4 trails in my neck of the woods:

My Jeep headed up Goler Wash in Death Valley NP!

 

These discussions are always interesting. From my experience, narrow tires on packed snow and ice. All other conditions, I will take the wide ones

 

I have found the same. You want to get through the snow, not spread the load on top of it.

I had a K5 years ago on Dick Cepek 36 x 16.5's (bought it that way) that in 2wd would just about slide off the road in 1" of snow if it was crowned. Even in 4wd it could barely make it up my street which really isn't that steep.

 

I have waiting for somebody to say this. LOL.
And I agree.
For snow you want those pizza cutter size tires.

 

I dont do much snow, but I have a four set of chains for my rig. Had to turn back on one high altitude desert trail that had frozen over. steep cliff, long way down on edge of a narrow trail. The flat parts had us sliding sideways, wed slide sideway even after stopping! no waywas we going to go the rest of way where sliding off meant death, so back we went. But frankly, I dont think I would have done that route even in skinny snow tires with chains. it was icey, slick as can be.

But yeah, I read up that big ole fat offroad tires are not necessarily the best for snow. However I have done some snow wheeling with them without complaints. I suppkse if I did a lot of snkw wheeling Id consider a set of snow friendlier wheel set for the snow, and the off road tires for non snow trails.

 

Indeed, in snow and ice chains will provide the BEST traction :

Xj on South Pass

 

Yup!