There is some very interesting theory and scientific data in this thread. I really enjoyed reading it...I have to admit, a lot of it was WAY over my head, but it is great to see and read.
Unfortunately, I am going to bugger it all up with some practical, unscientific observations!! Here's my take from
my experience.
I have had the pleasure of running a few of the tire sizes mentioned here on my rig. I started of with the stock 31x10.5. Not a bad tire, but not tall enough to allow for adequate ground clearance under difs and the low slung springs on a sprung under cruiser.
One of the only pictures I have of them on the truck. (completely stock)
My next tire was the ever popular size of 255/85R16. I actually ran two sets of these, a BFG MT and the Trxus MT. The Trxus was the better of the two as I really did not like the BFG MTs. These tires gave me the little bit of ground clearance I was after and the "classic" pizza cutter look. I even ran them on split rims for easy field repairs, sacrificing weight for that once "cool" factor... They turned out to be way to skinny for the weight of the truck. On the highway they where great, anywhere else, you sank to the bottom, slipped off, or simply spinned on the spot...
Sorry, I know it's another poser picture... My favorite "LOOK" but that doesn't help you get down the road.
Next up on my list was a great set of the Michelin 9.00R16 XCsL. I was in love with this tire. It was (and still is) the Ultimate pizza cutter!! I now had lots of ground clearance and a tire stiff enough to air down and not feel like I was riding a marshmallow. Tractions was pretty good in everything except the rain and ice (siping help tremendously) At least it was way better then the 255/85R16. Mostly due to ground clearance I would believe. You still sunk like crazy in the skeg and sand, but the on road manners where pretty decent although a little loud on the highway.
Better picture of them in use in some softer sand
After getting sick and tired of not being able to float on top of the skeg and sand that I typically see, I sourced out, what I think, is the ultimate tire for a big, heavy, expedition/offroad/onroad style rig. The Michelin 325/85R16 ZML. If you have the power and clearance to run these tire you are going to be very happy in most condition. They do very well in the soft stuff, are OK in the rocks and perform much better in the snow and ice then the XCL IMO. I also siped these for winter travel. Aired down the side wall is nice and stiff, I have never punctured one, onroad manner are good (still loud) but they are getting harder to find with a decent amount of tread left on them.
Size difference between the XML and the XCL:
On a "winter road" in the summer at Chitek Lake in northern Sask. I attempted this road the summer before with the 9.00R16 XCLs. It was a disaster.
and the poser shot to get perspective of them on the rig. You can see the 9.00R16 XCLs now see trailer duty.
Which brings me to my latest tire, a Toyo 38x14.5R16 MT. Just shy on height compared to the XMLs but a lot wider. And a lot lighter. I lost amost 25lbs a tire on rotational mass, increased my fuel economy and quieted down my ride, a LOT. This tire has been great so far. I purchased them last fall, and so far has been the best tire in the snow and ice. It floats on top of the deep stuff, has good traction on our winter roads and sounds good rolling down the highway. They also performed well on the back roads of Northern Sask near Missinippi, which consisted of rocks, mud, and potholes... These tires will be taking us to Alaska this year for Cruiser Trek 08.
For comparison, me beside a HJ60 with 31x9.5
The bottom line for me, bigger and wider has always been better for getting me from point A to point B. If I want to get from here to there, all else being equal, I will always take the truck with the bigger, wider tires. This has been
my experience in getting down the road. It does not take into account MPG loss, HP and torque required, vehicle mods to fit, common tire sizes (for replacement in remote areas) or any other factor not directly related to moving you along.
Like I said, not very scientific, but I enjoyed reading the thread. I don't know if anything I wrote matters, but I got to show you some pictures of my truck, I learned a lot from what others have posted, and I will be interested in what others experiences has told them about taller, wider tires.
