34x10.50x17 LTB on 17x7.5 stock base 1/2 ton chevy wheels

[glfredrick]

Those skinny tires will work best in one or two situations, and at all other times be a problem. I have a friend who runs 37" skinny tires on his Jeep and he has been upside down more often than the rest of the club combined. As a matter of fact, virtually every trip he tries ends up with him upside down on an obstacle. Once he side-slips a little bit, he just tips over, where a wider tire would plant harder and support the weight of the rig.

The conditions where they will actually perform well are, in up to 12" of snow, and in up to 6" of clay/mud, especially while trail riding where side-slip can be an issue.

Otherwise, they will be a roll-over waiting to happen, a bead just begging to get un-seated, and doors/windows just waiting to be caved in on trees and rocks.

For the type trails Kyle is now trying, he will need both height and width (to a point) so that he can use the sidewalls (sometimes we do more driving on the sidewalls than on the tread) and so that he can deal with off-camber situations.

Theoretically the smaller contact patch "should" provide more traction because the weight is concentrated into a smaller contact patch, but we don't wheel theory, we wheel real vehicles, and experience has proven that the physics proposition that indicates that the weight per square inch of the contact patch is not the only variable. Having more surface area under the contact patch is also important, and the more rubber one has on the rock, the more traction that can be gained. I know that the numbers might not work out, but let's suggest an experiment to see if the wider is better thesis holds out... I'm imagining a piece of sandpaper wrapped around a coke can. Let's try a 1" strip first. Then, let's try a 12" strip. Both have the same amount of down-pressure. Which one is easier to push along the surface of the material being sanded? Why? Physics indicates that the most amount of pounds per square inch is on the thin strip, so that should gain the most traction, but our real world experience adds "coefficient of friction" which is area specific. More area more friction, and so the larger strip is indeed the most difficult to push.

There is a place where you can over-tire a vehicle, and I see it often in off-road situations. Guys with "really" built rigs spin on stuff smaller trucks just drive up. The crowd that can't afford the big rigs feels smug in being able to top the high dollar trucks with the huge tires -- until the obstacle size grows and the little guy can't even get a tire on the obstacle.

[OregTrailBlazin]

Sometimes it is hard to tell when posting, but I really just hope my buying the wheels and tires, plus taking the time and minimal money to mount and balance them, then install them on the truck helps give others ideas. i will sell these and make money either way.

Some people they are a perfect fit, but for me they just don't fit my mission or desires.

It is much appreciated!! With a little less backspacing that is the route I would like to go! Thanks for Pioneering for us

[janesy86]

I hear ya exactly Kyle... I think the older set up looks better and would do you better offroad as well. Also think that it was beneficial to see what that size looks like on our platform, so I appreciate the time/$ you put into doing this for us, as some may go in that direction now or steer away.

I know when I go with larger tires I will go wider as well, since it would benefit me much more than skinnier tires.

[OregTrailBlazin]

I'm imagining a piece of sandpaper wrapped around a coke can. Let's try a 1" strip first. Then, let's try a 12" strip. Both have the same amount of down-pressure. Which one is easier to push along the surface of the material being sanded? Why? Physics indicates that the most amount of pounds per square inch is on the thin strip, so that should gain the most traction, but our real world experience adds "coefficient of friction" which is area specific. More area more friction, and so the larger strip is indeed the most difficult to push..

Wouldn't this be more relevant to your braking ability with narrow vs. wide?

Your comparing sliding sand paper vs. rolling a tire....

[irishboy02]

I agree and am testament to this. Your current setup was my inspiration for my setup now, only im slightly bigger. You gave the 15" rim a shot and i used your mesurements to make it work for myself. Your running the 305s, im 33x12.5, slight trimming, like you stated, but it worked.

Without this trial and error we wouldnt be where our platform is, not to mention the whole offroad world would be plain and boring.

Hats off to ya brother! Ill drink to that

[Trail X]

I'm imagining a piece of sandpaper wrapped around a coke can. Let's try a 1" strip first. Then, let's try a 12" strip. Both have the same amount of down-pressure. Which one is easier to push along the surface of the material being sanded? Why? Physics indicates that the most amount of pounds per square inch is on the thin strip, so that should gain the most traction, but our real world experience adds "coefficient of friction" which is area specific. More area more friction, and so the larger strip is indeed the most difficult to push..

Wouldn't this be more relevant to your braking ability with narrow vs. wide?

Your comparing sliding sand paper vs. rolling a tire....

Yeah... friction is a very tricky physics principal. There are people that are actually "friction engineers" - in speaking with one, he says the more he learns about friction, the harder it is to understand. There's macro friction, of the tire's rubber conforming to the surface, and teeth biting into the surface... then there's micro friction, which is friction at a molecular level.

Technically (and according to any physics book), contact area doesn't play into the amount of frictional force - only the normal force that is acting on the contact patch. However when you start dealing with macro friction of the tires integrating, conforming to, and biting into the surface of the road and wet vs. dry surfaces, patch size begins to become a contributing factor.

So you're right that trying to explain tire friction by describing sandpaper and coke cans is a bit abstract.

It really all seems to depend on intended usage and terrain - even then, people disagree about what works best. Case in point - some say skinny is better for mud, some say wider is better - all depends on your experience and how you look at it.

ETA - forgot to add - if contact area doesn't matter, why do dragsters use wider tires? It's because they are reaching the shear strength of the rubber - a larger contact area spreads their forces over a bigger area, and is less likely to shear the rubber (which is what happens when their tires break-away and spinout).

[glfredrick]

James, I proved your argument to my physics prof during my undergrad degree...

He made a big and bold argument in the class that I challenged. My remarks were going to cost me my grade for the semester because "no student dare challenge the expert instructor." So, with the ground rules laid down, I brought my 500hp Chevelle with two sets of rear tires -- one a nice set of L78 - 15 radials (approx 225/78) -- the other the BFG L60 15 radials (approx 335/60) I was running at that time.

With the L78s in place I pulled up to our testing mark and dropped the clutch at 7800 rpm. The amount of tire smoke was impressive, and the car would only move forward if I let off the throttle a bit. Otherwise it stood in one place and tossed melted rubber all over the fenders and by-standers. Eyes were opened at the capability of my "street sleeper" car -- it didn't look like it had that capability. Then, the tires were swapped and the experiment repeated. While I left a nice pair of stripes on the pavement, I also carried the front tires about a foot in the air and went in the other direction quite rapidly (the car would clock 12:18 @ 118 at Union Grove in the 1/4 mile). I repeated the test for clarity to much applause, and a prof scratching his head. I sort of exploded his worldview a bit.

I also got an A in the course for the semester because of my "lab" scores...

Off-road, I've seen the advantages of wider tires for all the reasons listed above. My current tires are 38.5 x 15.50 x 15. They may be too wide, but with some siping and grooving, I'm sure they will take care of business.

[KE7WOX]

It really all seems to depend on intended usage and terrain - even then, people disagree about what works best. Case in point - some say skinny is better for mud, some say wider is better - all depends on your experience and how you look at it.

A lot of people in Panama run quite narrow tires (what I believe are mostly SS in 33+ x 10.50 and seem to have zero issues. But they are notorious for the use of mud chains.

[HARDTRAILZ]

A lot of people in Panama run quite narrow tires (what I believe are mostly SS in 33+ x 10.50 and seem to have zero issues. But they are notorious for the use of mud chains.

Wont the tire chains effectively widen the tire footprint. Making them more like the common 12.50.

[Philberto]

I like that my cb antenna mount idea is working out well for you at least.

[KE7WOX]

A lot of people in Panama run quite narrow tires (what I believe are mostly SS in 33+ x 10.50 and seem to have zero issues. But they are notorious for the use of mud chains.

Wont the tire chains effectively widen the tire footprint. Making them more like the common 12.50.

I have no idea, but if that's the case, I'm buying a set as soon as I get back to the States.

[DmccartneyFF2TB]

Dame dame likey!!! dude i want....

[Philberto]

Now that this has been resurrected, I would like to add that these pictures definitely gave me confirmation for my skinny tire plans (255/85/16), and I like the Land Cruiser look, but then again, overlanding is my goal, specifically South America, where the use of these tire sizes and mud chains is quite common.

[HARDTRAILZ]

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