Wheel Narrowing....

[Hotrodvw]

So, what's the advantage to narrowing wheels? Doesn't it reduce the contact patch?

[CrawlerDan]

yeah it does,but it increases the pressure on the contact patch that is left. which means it will grip better and shape it self after the terrain more easy.

[MattH]

In my opinion, a narrow rim does two things: it changes the shape of the tire thus pulling tread down the side a bit for more side biting and it allows for more steering throw. I'm not sold on the small contact patch equals more pressure and thus more traction. If that was the case wouldn't sports cars come with really narrow tires?

[DISTURBIN' tha PEACE]

Originally Posted by MattH

In my opinion, a narrow rim does two things: it changes the shape of the tire thus pulling tread down the side a bit for more side biting and it allows for more steering throw. I'm not sold on the small contact patch equals more pressure and thus more traction. If that was the case wouldn't sports cars come with really narrow tires?

Do sports cars & RC crawlers weigh the same?

I would think that you of all people would know that not everything that works in RC works on 1:1's or vice-versa. Well, then again, maybe you don't.

[MattH]

Why the personal attack? Save that stuff for face to face conversations.

Back to the original point: I don't see narrowing rims as a viable way to increase traction through the theory that a smaller contact patch equals more grip because a more concentrated pressure.

[demonoid369]

Originally Posted by MattH

Why the personal attack? Save that stuff for face to face conversations.

Back to the original point: I don't see narrowing rims as a viable way to increase traction through the theory that a smaller contact patch equals more grip because a more concentrated pressure.

to tell you the truth it's true, the smaller the spot the more pressure, thats why nails are thin and pointy! it puts more pressure in a tiny spot to let it pierce whatever it is. You don't see nails wide and large do you???
So the smaller the patch the better the grip and pressure.

[MattH]

I was waiting for the needle or nail analogy. Food for thought ... I believe the "pressure" stays the same. Using the nail example: the force or pressure placed on a sharp nail is the same amount that gets placed on the hypothetical flat nail. In auto speak, I believe they refer to the "pressure" as the vertical load and state that's a constant (unless something outside of the tires changes). The reason the pointy nail pierces the material is that grip (friction) is reduced and, also, less material has to be displaced.

In my experience, a narrow rim does two things: it changes the shape of the tire and allows for more clearance around the 4-links. If it narrows the tire also, I do not see how that increases traction because of a reduced contact patch. Does that mean we should be running really wide tires? No. This is because, like with everything in rock crawling, there is always a trade off and a point of diminishing return. Just my opinion.

[holycaveman]

I have been messing with this alot lately.. A narrow rounded contact area DOES increase traction on uphills. lbs per square inch. just do the math. x amount of weight on a 2 inch contact patch = p amount of pressure. The same x amount of weight on a 1in contact patch and p(pressure) will figure alot greater. More pressure on a given area especially when going on rock uphills is a large benifit. Just push on the front of your crawler while its spinning, it will stop spinning and start climbing. So if P is increased, then also tire spinning is reduced from the increased pressure. However there is a fine line you have to follow. You can't go overboard. But alittle makes a good difference.

This is why I attribute the moabs and claws to good traction. I also recently have adapted a round profile to my modified red rocks. Now they arguably work better than the said two.

Sportcars is a whold different ball game. You need strong sidewall support for cornering and stability, therefore a low profile. Also you have the perfect traction anyways with tarmac. It doesn't change to much. Not apples to apples for sure.

[mysharona]

WRONG WRONG WRONG. changing the tire contact patch does not increase traction. the only way traction is going to change is by having the right shape lugs for the current conditions. If you take a brick and lay it down, it takes just as much force to move it laying down as standing up. this is because the COEFFICIENT OF FRICTION doesn't/can't change. The only way to increase the pressure/friction between tire and ground is to add weight. basic physics.

Narrowing the wheel will pull the tread onto the side wall to give you more side traction. as stated, it will also narrow the overall tire allowing more clearance between tire links.

[holycaveman]

That is what I origionally thought. So I just changed the lugs, but there was little if no improvment at all with the tires. Its only when I changed the shape of the tire and narrowed the contact patch when I saw the most improvement. So much that lug shape does not mean so much anymore. Rather compound and overall tire shape. I would wagger money that if you changed the shape of the losi claw lugs, but kept everything else the same, and the same size lugs, it would do just as well. After all its rocks, not mud.

I am a newb, but I don't learn vicariously, I have to try everything out for myself.

[TURBOFEST]

well, besides the whole traction thing a narrower tire makes the demand on steering hardware and servo much less...it also reduces the track width of the rig whish will make it more manueverable through gates and what not.

[red jim]

Originally Posted by mysharona

WRONG WRONG WRONG. changing the tire contact patch does not increase traction. the only way traction is going to change is by having the right shape lugs for the current conditions. If you take a brick and lay it down, it takes just as much force to move it laying down as standing up. this is because the COEFFICIENT OF FRICTION doesn't/can't change. The only way to increase the pressure/friction between tire and ground is to add weight. basic physics.

Narrowing the wheel will pull the tread onto the side wall to give you more side traction. as stated, it will also narrow the overall tire allowing more clearance between tire links.

Doesn't the contact patch change on a brick too,more square inches on the side than the end.So in theory if a surface was perfectly flat you would be correct but rocks are seldom perfectly flat.I think this would make a difference,wouldn't it.

[JasonInAugusta]

This was debated two years ago.

[demonoid369]

Originally Posted by red jim

Doesn't the contact patch change on a brick too,more square inches on the side than the end.So in theory if a surface was perfectly flat you would be correct but rocks are seldom perfectly flat.I think this would make a difference,wouldn't it.

you very right not all the rocks are flat but even so, ex: lay a flat piece of alumminum foil on water it floats but if you krinkle it up and put it on water it sinks immediatly, becuase there is less pressure on the water, becuase it spreads the wieght around, compare to centering the mass to one area.

[holycaveman]

Originally Posted by JasonInAugusta

This was debated two years ago.

Only because you are an old guy(crawling wise) so this is probably boring to you. LOL

I personally believe its the driver over every other element. But sometimes these little things help, if anything make it more entertaining

[CrawlerDan]

its pure logic that the pressure gets higher when the contact patch gets smaller. this is mostly an advantage on loose surfaces. look at the rally cars. when driving on snow or loose gravel they run really narrow tires. this makes the tire dig down into the surface for more grip. on the rocks this doesnt make much difference until you start climbing ledges and stuff that needs extra bite. for 1:1 cars they run wide tires on tarmac because of the high speed they drive at. when turning at high speed the contact patch reduces and therefore they need wider tires to maintain a resonable amount of grip. dragsters are also a good example of why they run wide tires on tarmac. if you look at a dragsters rear wheels when it steps of the starting line they expand very much and when they expand the contact patch reduces.

[muddeprived]

I'm not gonna jump into the scientific pressure talk but the reason i narrow my wheels is cuz i like running narrow tires in the mud. They perform alot better than fat and wide tires. My stock 2.2 all-t's do shi$$y in the goo while my narrow 2" all-t's excel.