Oh ok, well, that settles it then.
100 series performance in soft sand (1 Viewer)
- Thread starter Kekoa12
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I think we established, contact patch is not larger on wider tire, it’s a function of vehicle weight and pressure. It’s only wider.
Who’s good at math? Given: you have two 33” tires, one’s a 255, one’s a 315, each holding 1500lbs (1/4 of a 6k lb truck), both at 20 psi. How much longer is 255 patch? How much more could each air down without losing a bead? Assuming the 315 could air down an additional 5 psi lower and the 255 can’t (is this even true?), would this be enough to give the 315 a longer contact patch?
Who’s good at math? Given: you have two 33” tires, one’s a 255, one’s a 315, each holding 1500lbs (1/4 of a 6k lb truck), both at 20 psi. How much longer is 255 patch? How much more could each air down without losing a bead? Assuming the 315 could air down an additional 5 psi lower and the 255 can’t (is this even true?), would this be enough to give the 315 a longer contact patch?
WarDamnEagle
SILVER Star
All of the 70 series pickups over here use tall skinny light truck tires with no AT or MT characteristics at all. I think you generally want very limited tread pattern in sand. You want maximum contact for a given contact patch and you want that in one plane - no deep treads.
FWIW, all the bedouins drive those pickups and they are the kings of the dunes. Just my observations/ opinion.
WarDamnEagle
SILVER Star
Let me elaborate please. At any given tire psi, the surface area of the tire in contact with the supporting terrain will be the same regardless of the tire width. You won’t have more surface area with a wider tire unless you lower the tire pressure. And guess what? If you lower the narrow tire to the same pressure then you will have the same surface area. The same.
Now what I want to know is why I can run lower air pressure in a wider tire? I would think the only reason would be that wider tires don’t come off the rims. If that’s the reason then please tell me why because I would like to know. I run splits on my 75 pickup and have had a hard time deciding how low I can go. Would love to learn something.
it was ambiguous. To clarify, MT tires traditionally have taller lugs and more of them. This creates surface area for more contact. You had mentioned the need for the most possible contact area. The problem is, MTs tend to dig down. Which is good when used as intended. However for sand it’s counter productive. You want the least amount of rolling resistance possible while still having traction.
Same here in north Florida, running 285/75/16.
I don't know how it would do in the super fine sand I've seen in videos, like this guy in Utah (start at 9:41):
Yes, I'm saying that the bigger the contact area, the better. I say this because sand will "shear" (by that I mean tear against itself when force from the tire is applied) very easily. So, the greater area will provide you with more thrust from the tire.
Are you saying that greater area (contact patch) is counter productive?
I think this discussion is a little confusing (and a little off topic). I can’t speak for divemedic but I think you’re both in agreement that more surface area is better (along with all the rest of us). The confusion is from the myth that wider tire = more surface area. Surface area is equal, assuming other conditions are also equal (including tire pressure), just the tire dimensions allow the tires to deform differently.
Really, wider tire = wider contact patch and narrower tire = longer contact patch, which is preferable because the added traction is along the axis of motion (We’re not high speed cornering).
nukegoat has said that wider tires can be aired down more thus creating bigger contact patch (wider and longer). No one has verified if this is true. Two questions: 1, can wider tires be aired down more (And why)? 2, if they can, will the increase in the long axis of that larger contact patch be enough to surpass the skinnies in traction? Maybe so. We’re all on the edge of our chairs.
No. We agree contact patch size is very important.
I was only stating that a MT-type tire is counter productive in sand due to its engineer characteristics. The lugs of a MT increase the contact patch in multiple directions (I.e. vertical penetration into the substrate).
I agree with your synopsis fully.
My answers to your questions:
No, wider tires cannot be aired down more than narrow tires with the understanding that the tires is mounted to an appropriate width rim (I.e a wide tire on a too-narrow rim). A 315/70r16 is roughly a 33x12. A 255/85r16 is roughly a 33x10. Both go on 16-inch rims. Both have a rough sidewall height of 8 1/2 inches. Both have very similar contact patches; the 33x12 is wide, the 33x10 is long.
Given a 33x12 and 33x10 can be air down equally. The 33x12 will get wider and longer. The 33x10 will get longer and wider. Their inherent characteristics do not change they are enhanced.
Does a wide tire work on sand? Generally, yes. Just not as efficiently as a narrow tire.
Does a narrow tire work for rock crawling? Yes. Just not as efficiently as a wide tire.
The OP asked specifically about beach driving. Tall narrow tire is better. Had they asked about crawling, my answer would be different.
For the record, I believe:
315/70/r16 is a wide tire
295/75r16 is a medium tire
255/85r16 is a narrow tire
They are all 33-ish inches tall
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I'll just leave the discussion with a couple links:
First, Four Wheeler Magazine Skinny vs Wide Tires: Summary is that floatation provided by wide tires makes them BETTER in sand. All 4 editors agree.
www.fourwheeler.com
As for tire pressure versus tire size (volume of air inside the tire). Here's a question and answer from Southern Illinois University on the topic.
questions.packback.co
Great topic and have a good day everyone.
First, Four Wheeler Magazine Skinny vs Wide Tires: Summary is that floatation provided by wide tires makes them BETTER in sand. All 4 editors agree.
Skinny vs Wide Tires! Versus!
Tall and skinny versus short and fat. Sounds like a horrible lead-in to some sort of terrible celebrity reality TV fight night series, but anyone who eats, brea
As for tire pressure versus tire size (volume of air inside the tire). Here's a question and answer from Southern Illinois University on the topic.
Packback
Packback is an online learning community for students to discuss high-level questions.
Great topic and have a good day everyone.
Q- what’s the best tire for sand?
A- wide tires. They have better floatation.
Q- why do they provide better floatation?
A- because they’re wide.
Q- But why do provide better floatation?
A- because when I look at them, I see they’re wide. Therefore they float better.
A2- actually, a narrow tire is inherently better.
Q- why is a narrow tire better?
A2- evidence based responses with numbers, science, and best-practices from; Middle East, Australia, Africa, military, Mongolia, professional expidition drivers, Dakar racer teams, etc. Also voodoo makes em more gooder. Voodoo is the key.
A- but they’re wide! Would ya just look at it? Plus you can air down further! AND an op ed from 4wheeler says they look cool and provide floatation. Don’t believe the voodoo hype!
Q- yeah, but why?
A- because they’re wide.
continue circle-jerk
A- wide tires. They have better floatation.
Q- why do they provide better floatation?
A- because they’re wide.
Q- But why do provide better floatation?
A- because when I look at them, I see they’re wide. Therefore they float better.
A2- actually, a narrow tire is inherently better.
Q- why is a narrow tire better?
A2- evidence based responses with numbers, science, and best-practices from; Middle East, Australia, Africa, military, Mongolia, professional expidition drivers, Dakar racer teams, etc. Also voodoo makes em more gooder. Voodoo is the key.
A- but they’re wide! Would ya just look at it? Plus you can air down further! AND an op ed from 4wheeler says they look cool and provide floatation. Don’t believe the voodoo hype!
Q- yeah, but why?
A- because they’re wide.
continue circle-jerk
Well, you're wrong. Narrow and wide tires can't be aired down the same. Wide tires are better because you can air them down farther and create a greater contact patch. You can do this for the reasons in my second link, from Southern Illinois University:
The question: Why do smaller lawnmower tires operate at higher pressures than large ones?
Answer:
All four tires on the lawnmower hold up the exact same amount of weight. Because the tires are responsible for an equal portion of the total weight, they must all contain the same amount of air molecules to keep the mower upright and balanced. Because the larger tires have a much larger space for air to go, the air molecules within that system are under a lot less pressure. When filling up the smaller tires, their air molecules need to be packed into a much smaller area. The consistency in amount of air molecules needed in each tire and the difference in the amount of space for those air molecules causes the great difference in pressure per tire. The smaller tires will need to be filled to a much higher pressure than the larger tires. (there is more explanation after this quote, but you get the picture)
As for Dakar racing, BFG is the official tire for dakar... they use a 12.5" section width on a variety of tires, 35s and 37s
BFGoodrich All-Terrain T/A KDR2+ - BFGoodrich Racing
The BFGoodrich All-Terrain T/A KDR2+ tire takes BFG’s decades of experience in both North American desert and International Rally raid competition to new heights. Available in Medium, and Soft Compounds. BFGoodrich brand logo in color on sidewall on 37″ size offering. CAI MSPN Dimension Compound...
www.bfgoodrichracing.com
How's that for Voodoo?
That open-source question is literally the dumbest s*** posted here. They’re using lawn tractor tires which have hugely different front to back mostly in the sidewalk construction. They don’t account for other gas laws... by that logic the average recommended pressure for a mountain bike tire and average recommended pressure for a car tire should be hugely different. Yup, around 50psi.
the laws partial pressure of gas is not based on its container.
run distribution equations comparing a 33x10, 33x12, 37x15 and 37x12
guess what, 37x12 is a narrow tire.
the laws partial pressure of gas is not based on its container.
run distribution equations comparing a 33x10, 33x12, 37x15 and 37x12
guess what, 37x12 is a narrow tire.
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You missed it again. The question is an apples to apples comparison of the same type tire, only changing size. There's no comparing truck tires to bicycle tires going on in there.
OP - if you got the tl;dr point 
... Yes, a 100 series will be fine in sand.
As an aside - Run whatever tyres you want to make your dick feel bigger, chode or pencil will both get the job done
... Yes, a 100 series will be fine in sand.
As an aside - Run whatever tyres you want to make your dick feel bigger, chode or pencil will both get the job done
So based on that magazine article, you need 37” tires for sand OP. Got it?
Ok, but how wide???
37 inches.
Found this picture of a standard sand tire for the 100 series. Hope this helps.
