When NASCAR takes over the Olympics

March 13, 2013 9:11 AM

Tire jumping in japan The olympic sport where the auto enthusiast can comment endlessly about the tire he used to have, that would have won.
posted by boilermonster (39 comments total)

This is great. They could make an all-tire-jumping channel and I'm sure I would find myself watching it entirely too often.
posted by Sys Rq at 9:29 AM on March 13 [2 favorites]

I assume my friend who teaches high school engineering is already trying to figure out how to work this video into lesson plans.
posted by midmarch snowman at 9:34 AM on March 13 [1 favorite]

Oddly mesmerizing.
posted by jbickers at 9:38 AM on March 13

I don't get why the take off speeds are so vastly different. They are basically powered by gravity so they should accelerate at the same speed, ramp or no ramp, right?

The only thing I can think of is that more mass preserves more of the momentum when it hits the ramp and there might be something about the friction over whatever surface they're rolling over.
posted by VTX at 9:38 AM on March 13

I think they should replace the tire release guy in the lab coat with some kind of mechanical release.

Then again, the true skill may be the release, I'd like to see a competition between teams of lab coat wearing contestants, maybe one team per country, releasing a standard "tire", maybe made out of carbon fiber or precision milled out of aluminum to ensure consistent weight.
posted by Ad hominem at 9:41 AM on March 13

This is great.

VTX, they have different moments of inertia and different coefficients of friction on the ramp. The different masses play a role too when they face that last rise, as is made very evident.
posted by Songdog at 9:44 AM on March 13

I love how the Japanese for "sports car tire" appears to be "sports car tire," more or less. What an oddly specific sort of phrase to borrow from another language. Well, maybe it was two mostly-unrelated borrowings.

They are basically powered by gravity so they should accelerate at the same speed, ramp or no ramp, right?

I would guess that at such speeds (100+kph), air resistance becomes a really big deal, in which case it makes sense that the heavier ones have an edge.
posted by Western Infidels at 9:46 AM on March 13

I think that if there were 500lbs of tire coming at me upwards of 100km/h I would not be moving back and forth trying to catch it like the player in a real-life game of Kaboom!

In conclusion, Japan is a land of contrasts.
posted by seanmpuckett at 9:53 AM on March 13 [5 favorites]

I love Japanese TV. Absolutely love it. The greatest moment is when they're all like "and now for the really big tire!"
posted by DoubleLune at 9:56 AM on March 13

Size relative to mass probably counts for a lot. Larger, lighter tires are more affected by air resistance. The utility truck and F1 tires are roughly the same diameter, but the truck tire is less than half as wide and weighs 48 kilo, while the F1 tire weighs 11 kilo -- the truck tire jumped twice as far.

I also wonder whether the concavity of the tire has any effect on air resistance, and if so whether this affect changes depending on tire shape.
posted by ardgedee at 9:59 AM on March 13

If you like this, then you'll love ski jumping pairs.
posted by The Tensor at 10:12 AM on March 13 [4 favorites]

They are basically powered by gravity so they should accelerate at the same speed

You've been hoaxed by Big Gravity, just like that sap Galileo. TEACH THE CONTROVERSY!
posted by yoink at 10:16 AM on March 13

I think there's a nice little interplay between the weight, air resistance, and tread (i.e. friction). I saw this the other day and was absolutely delighted. It's so ... just fun and great! Why are all our shows such garbage in comparison?
posted by BlackLeotardFront at 10:18 AM on March 13

I don't get why the take off speeds are so vastly different. They are basically powered by gravity so they should accelerate at the same speed, ramp or no ramp, right?

They weigh vastly different amounts so air resistance will be a variable factor. Plus sidewall stiffness is a big factor. The softer the sidewall, the more energy it absorbs as it squishes as it transitions/changes direction to the kicker ramp (the bit the massive tyre destroyed). You see the F1 tyre (with a very soft sidewall by comparison) oval noticeable compared to the others.
posted by Brockles at 10:20 AM on March 13 [1 favorite]

Yeah, the slick tire has a much lower takeoff speed than the others, so friction is playing a big role. Also I think the stiffness of the tire might be a factor?
posted by grog at 10:21 AM on March 13

I occasionally wonder what percentage of white lab coats in Japan are sold to game show hosts.
posted by Tell Me No Lies at 10:22 AM on March 13 [1 favorite]

The last competitor would've won hands down were it not for the flimsy plywood!
Then a Cat 797 tire would've rolled down the ramp and landed in the ocean.
posted by hat_eater at 10:28 AM on March 13

Robert would have destroyed all of them.
posted by haltingproblemsolved at 10:31 AM on March 13 [3 favorites]

I don't think it is as much friction as rolling resistance (the energy required to compress the proportion of rubber touching the ground from the weight of the tyre on it). If friction wasn't an element at all, they'd slide, not roll, so I don't think friction in itself is necessarily slowing the tyres down.

I'd like to have seen a speed trap right before the kicker ramp. I bet the difference in speed there would be markedly different to the speed trends on ramp exit.
posted by Brockles at 10:41 AM on March 13

I'm not sure if these guys really count as athletes. : )
posted by empty vessel at 10:46 AM on March 13 [1 favorite]

This is interesting to watch.

Here's the off-road version.

But watching real people ski jumping is much more interesting than this.

Bonus: the thrill of victory and the agony of defeat.
posted by chavenet at 10:49 AM on March 13 [1 favorite]

I don't get why the take off speeds are so vastly different. They are basically powered by gravity so they should accelerate at the same speed, ramp or no ramp, right?

The tires have different weight distributions, and different moments of inertia. The tires that do best have a larger fraction of their weight on the sidewalls rather than in the tread.
posted by Killick at 10:51 AM on March 13

the gravitational force on each of the tires is constant (see galilleo), what changes is the radius of the tire: bigger radius = greater torque = faster rolling acceleration = faster take-off speed. the tractor tire would have won if it hadn't demolished the take-off ramp.
posted by ennui.bz at 10:52 AM on March 13

I'd like to have seen a speed trap right before the kicker ramp. I bet the difference in speed there would be markedly different to the speed trends on ramp exit.

Oh, I thought it was before the ramp, but I didn't look too closely. If friction isn't the right word, maybe adherence? I just imagine the slick tires to be more "sticky", but is that just another way of saying rolling resistance?
posted by grog at 11:11 AM on March 13

I think you're looking for "rolling resistance." If the rolling resistance was 100%, the tire would just stick in place and not roll at all.

The slick tire is probably not very sticky at all. They have to operate at very high temperatures that are usually only reached at race speeds. When they're at room temp, they can be as hard as rocks.
posted by VTX at 11:21 AM on March 13

I'm curious why the Youtube video is titled "Tire Ski Jumping Japan Prank"

How is this a prank? Is this an YTO* thing that they've found more they get the most clicks from things that say "Japan Prank" in the title?

*YouTube Optimization
posted by RobotHero at 11:32 AM on March 13

You're looking for sense and logic on youtube? That way lies madness and deep disappointment, my friend.
posted by Brockles at 11:36 AM on March 13

I just imagine the slick tires to be more "sticky"

Not at all. As VTX says, at room/outside temperatures slicks are not at all sticky. Smooth and relatively hard.
posted by Brockles at 11:38 AM on March 13

That's an awfully long setup just to prank a tractor tire with a break away ramp. I don't think tires are so smart that you have to make it look all official and everything.
posted by orme at 12:18 PM on March 13 [4 favorites]

Yeah, I think Killick has it, it's the rotational kinetic energy that's the main difference, but you want to keep that as small as possible as it's the translational K.E that will go into making your tyre take off, spinning it round is wasting energy.

The mass distribution determines the moment of inertia, for a cylindrical shell ( found here ) I = mr^2, but that means the big tyre will have the greatest moment (the r^2 term's gonna dominate everything else). I bet if it hadn't smashed through the ramp it wouldn't have gone very far.

Related note: My physics tutor was fond of telling a story about a trip to Legoland he had with his son. There was a challenge to build a trolley to race down a ramp as fast as possible. All of the children he was competing against spent a lot of time making their cars look cool and streamlined. My tutor got the smallest wheels he could find and put them on a massive misshapen lump of bricks. He set the record time, and managed to win by a huge margin against a group of ten year olds, which made him incredibly proud.
posted by Ned G at 1:10 PM on March 13

This a clip from a TV show simply called "Trivia", and I'll bet this was part of a segment in which people write into the show with "What if....?" questions. The producers will pick one suggestion and roll with it with setups like this. Sadly, "Trivia" isn't on any longer and it's a shame. A very droll (the production crew wearing white lab coats and poker faces) and entertaining show.
posted by zardoz at 2:08 PM on March 13

I want to see Top Gear's take on this. They'd probably strap the Stig into one of the tires.
posted by Charlemagne In Sweatpants at 2:17 PM on March 13

That's some mighty entertaining television right there. I watched it twice, enjoyed it immensely both times.
posted by Purposeful Grimace at 2:22 PM on March 13

Charlemagne In Sweatpants: "I want to see Top Gear's take on this. They'd probably strap the Stig into one of the tires."

Or Jackass. They'd probably roll whole cars off the jump, with people in them.
posted by chavenet at 3:22 PM on March 13 [1 favorite]

I want to see Top Gear's take on this. They'd probably strap the Stig into one of the tires.

Yeah, and then they'd make up some bullshit about how the electric tire didn't make it as far as the ramp.
posted by Sys Rq at 4:02 PM on March 13

You're looking for sense and logic on youtube? That way lies madness and deep disappointment, my friend.

Well, I was wondering if that's a new rule that emerged from those murky depths? Now all Japanese TV is "pranks" like how all commercials are "BANNED" or you should always use a shot of cleavage for your thumbnail.
posted by RobotHero at 5:05 PM on March 13 [1 favorite]

Glad some people came in with some math here. I figured it had a lot to do with weight in relation to size, with the distribution of the weight thrown in.
Am waiting for the vintage tire jumping segment to be made by someone.
Wagon wheels ,vintage balloon tires, and whitewalls.
posted by boilermonster at 5:30 PM on March 13

This was discussed on the F1 forums the other day (while we anxiously await the season opener this weekend!):

The acceleration would in the most part be dependant on the ratio of weight to the moment of inertia, since all of those tires had enough grip to not slip. Therefore a tire where the weight would not only be on the rim but closer to the Centre would have lower moment of inertia and could accelerate faster. At the end of the slope the Energy gained from gravitation is divided into kinetic and rotational energy, and again the tire with the more centered weight distribution has an advantage. I'd guess that drag has a smaller influence on the slope, but of course is very important in flight, but again in relation to the weight. So overall a tire with a narrow width and a centric weight distribution with high density should perform best.

An easy way to improve the shown results would be to put the tires on their rims.

Add in consideration of tyre deformity (stiff, rigid tyres would have better rolling resistance) and I think he's got it.
posted by ceribus peribus at 5:43 PM on March 13

Suspicions are correct: the poster of the video is a lying liar who's lying to us.
It's Youtube click optimization, but also a somewhat interesting crystallization of the "wacky Japan" meme. I've been irritated at the idiocy of the "BANNED" phenomenon, but this one actually makes me rather angry.
I've been living in Japan for about ten years, and until last week, it had never been even remotely as Japan as America thinks Japan is.
For the curious, what broke that record was an elderly woman pulling a cat (which was wearing clothing, of course) down the street by a cord as it balanced on a tiny red tricycle. The cat seemed to be enjoying the ride, and did not attempt to dismount.
posted by GoingToShopping at 12:05 AM on March 14