This is one of the most useless articles ever posted too HN.
Weighing a Car with Tire Pressures
111–120 of 121 posts
Re: Weighing a Car with Tire Pressures
#112I'm late to the game, and probably no one will see this, but I thought I'd mention that I tweeted about this back in 2017:
https://twitter.com/ColinTheMathmo/status/870678851390537728
The ensuing discussion was wide-ranging, and covered various limitations of this technique. It was more true of older tires, but tires now have more structure, so some of the car's weight is supported by the tire structure, and not just by the air pressure.
In turn, I remember reading about this in a Martin Gardner book, probably nearly 40 years ago.
Re: Weighing a Car with Tire Pressures
#113Back when Microsoft was doing those obscure job interview questsions like "how much does a 747 weigh", this was my solution, measure the deflection of the tires and the PSI to calculate weight. Apparently the answers they were looking for were more along the lines of "put the plane on an aircraft carrier in a lake and measure the water displacement"
Lol, my question to that would have been how do you get the 747 on the aircraft carrier?
That's actually a harder question than getting the weight of one... which makes the entire exercise ridiculous.
Re: Weighing a Car with Tire Pressures
#114I'm late to the game, and probably no one will see this, but I thought I'd mention that I tweeted about this back in 2017: https://twitter.com/ColinTheMathmo/status/870678851390537728 The ensuing discussion was wide-ranging, and covered various limitations of this technique. It was more true of older tires, but tires now have more structure, so some of the car's weight is supported by the tire structure, and not just…
You made it to the top of the comments section.
Re: Weighing a Car with Tire Pressures
#115> I have a decent pressure gauge that I got for $25, so I feel I can be reasonably accurate. Such a false sense of confidence for a product[1] whose actual performance specs aren't properly published. And it isn't just Longacre playing this game. If you're in the recreational motorsports scene, you've probably noticed what I'm referring to. If you're an engineer in the same, it probably has driven you nuts. I'm not e…
Any recommendations for decently precise tire gauges ?
Digital ~230 USD - https://www.mcmaster.com/pressure-gauges/pressure-and-vacuum...
Analog gauge ~100 USD -https://www.mcmaster.com/pressure-gauges/pressure-and-vacuum...
Both of the above gauges come with Calibration Certificate Traceable to NIST
Re: Weighing a Car with Tire Pressures
#116Another option is to measure the compression of the suspension springs and then use the spring rates and the suspension motion ratios to calculate the corner weights.
If course that would only give you the sprung weight, but you could jack up a corner and then weigh just the unsprung components with a single bathroom scale. (Subtracting any contribution from the spring, if it's still compressed at all.) Either that or remove and weigh a wheel and then estimate the rest.
Re: Weighing a Car with Tire Pressures
#117theydidimperialmath. impressive.
Re: Weighing a Car with Tire Pressures
#118> The first thing I wanted to do with my Saab 96 was to establish a baseline weight. The cheapest scales used for racing are over $700, You can do this for (almost) free if you go to the local dump. They usually charge you based on weight of what you dump by weighing your car on the way in and on the way out. Just ask them what the reading is on the way out. If you bring a couple of pounds of garbage, it will cost a…
In Santa Clara near the airport there was (and probably still is) a paper and cardboard recycler. The scale is off a public street near some train tracks. At some point in college we noticed that the scale stayed on at night and the weight was clearly visible in the kiosk across the street. So me and my car buddies used to weigh our cars there for free at night!
they are still there!
Re: Weighing a Car with Tire Pressures
#119I'm late to the game, and probably no one will see this, but I thought I'd mention that I tweeted about this back in 2017: https://twitter.com/ColinTheMathmo/status/870678851390537728 The ensuing discussion was wide-ranging, and covered various limitations of this technique. It was more true of older tires, but tires now have more structure, so some of the car's weight is supported by the tire structure, and not just…
You made it to the top of the comments section.
That's ... genuinely surprising ... thanks for letting me know!
(Sorry people are downvoting you for that, I appreciated it.)
Re: Weighing a Car with Tire Pressures
#120Earlier quoted context omitted.
I guess I'm way out of date. I remember hearing that people who ride e.g. PBP run way wider tires than normal road racers because of the road conditions, but I didn't realize that the mainstream road racers were running that wide now. Also: hookless? Like they got rid of in, like, the '70s or '80s? My beater road bike (that's older than I am) has 630mm hookless rims, and I got a discount because of it. Are the new on…
Well, a lot of this is driven by the gravel racing gang... the people partying at gravel events are already happy running 40+mm width, or MTB tires, on very wide rims. But there's also a growing segment of people who have figured out that you can have a bike that's a little bit more comfortable off pavement by going wider, without totally compromising speed on the pavement, and it also makes tubeless less likely to b…
I’ve gone from 700x25 to 700x35 to 650x42 and I’m never going back. The wider tires are no slower, and a hell of a lot more comfortable. That may be because I am in a land where bad chipseal is good pavement, but even on Germany’s smoooooth roads, they still fly.
The new tubeless rims are different than the old ones, and There’s a lot that went into reducing the variance in the rim the rim / tire interface.