Flamedx4

A wonderful example of "In theory there is no difference between theory and reality. In reality however, there is."

The total friction may be the same, but there will always be more available traction offroad with a narrower tire. It's about loading, a larger footprint has a lower pressure on the ground for each square inch of the contact patch, therefore is easier to break loose. You will do much better in mud and dirt with skinnies - they dig down in mud and may better find something to bite on, and on dirt or whathaveyou they put more weight on the tread to get grip and keep you moving. With harder surfaces it can go either way. In sand, the narrower tire's better bite will dig holes - not good. So wider - assuming you get wide enough to provide some flotation - will probably be better. On snow, narrower tires give a better bite and better traction - but in Deep snow, wide enough to provide flotation might be best (gotta go REAL wide though!) Also note that larger diameter tires increase the footprint too, and mathematically/geometrically allow for a better climbing, final gearing being the same. Whether wide tires or narrower tires are better for your type of wheeling is the issue each has to decide. Like most things, there is no "best" answer - it's all relevant.

CzViper07

[QUOTE=Flamedx4]A wonderful example of "In theory there is no difference between theory and reality. In reality however, there is."

The total friction may be the same, ...

mike_d posted a link to some COF results for various metals. A little disclaimer at the bottom of that site says that most of the test condition details were not included. Most notably, Normal Force and Contact Patch area. Most of us may remember that friction force can be simplified to Ff = Cf x N. Or, Friction force is equal to the coefficient of friction multiplied by the norm al force. In reality coefficient of friction is dependent on material properties (rubber type, lugs, siping, studs, dirt/sand, rock/skree, wet/dry, ice/snow, etc.), contact patch area (tire inflation, tread width, road surface topo, etc.), and the weight each tire is being required to support. Also, coefficient decreases as soon as we begin to skid (kinetic COF vs. Static COF) and is one of the reasons for ABS and traction control. Think of a maximum traction situation: an F-1 car width 24 inch wide tires, cambered to ride flat on the road surface, softest rubber possible, no tread, traction control to keep all tires stuck to the road at all times, and with enough down force to effectively double or triple the cars weight at top speed.

in our case, we dont have the advantage of 24"tires or an ideal roadsurface but we can play around with tire width, diameter, tread, pressure, and suspension flex. increasing diameter can increase contact patch at high entry angles and on rough terrain. Width is obvious. and Airing down can cause the tire to "flatten out" agains the road surface. Increasing flex can allow the wheels to stay in contact with the ground longer. Although taking one wheel off the ground will increase the weight applied to the other tires, the gripping power of deep off road tires makes it almost always more advantagious to have all four tires on the ground as possible (not to mention those of us whod be stuck without diff locks).

Getting back to the original argument, is a wider tire better? Yes. Say we have the case of one tire bearing 500 lbs of load and we try to accelerate slowly. The higher our force of friction the faster we can accelerate. Adding weight to the vehicle may help (but would hurt us at the same time for several other reasons) but a higher COF would be best. A wider tire would have a bigger contact patch and therefore a larger COF even though, yes, the force/area is decreased. There will also be more lugs / sipes gripping the road. The only exception to this is when we may find a better surface deeper in the muck (shallow mud, light snow).

So, in conclusion, wider is better most of the time and COF does depend on contact patch area.

:pat:

jeremys73

For me, I'm not concerned about which width has the most traction. If that were the case, and wider ones have more, I think they make 33x14 sizes. I will get a lot more traction having an aggresive tread, and from an increase in contact patch, a rear locker and maybe a LSD up front b4 long

For me, it's that I can get that height, the narrower ones are cheaper, they fit without lift (cheaper), better mpg's, etc... As far as sand goes, I had 31x10.5's on my '91 pickup and being so light, I never had a problem in sand around here.

For me, I will get the extra traction going from these



to these Coopers (Big O Bigfoot XT & CT also available in 255/85/16)

jeremys73

Here are the Big O Bigfoot XT
http://www.valleyimall.com/bigotires/truck.html

Cooper Discoverer "free shipping"
http://www.discountedwheelwarehouse....ue&SnipID=4294

4Crawler

iTrader: (3)

I run 33x10.50s and they work great on my 1st gen. I have also run tires as narrow as 9.50 and as wide as 15.50" wide. There are conditions in which a narrow tire will work better than wide and vice versa. I find narrow works well in deep snow, takes less effort to push the narrower tire through the snow and the 10.50s float quite well. In a tall, skinny tire, you'll get a longer contact patch than wil a wider tire at the same pressure. In snow, if you can get the tire to compress the snow ahead of it and then pack the snow into the tread voids, you can get traction from that longer patch of packed snow. I have literally driven circles around rigs with wider tires as they are buried to the axles in snow. Sometimes, wider is better, too. It all depends on the terrain.