If you're any kind of a car person, you owe it to yourself to check out the rest of The Autopian - it's an independent car site founded, owned, and operated by deeply weird car people, and it's absolutely amazing.

Here's their writeup on the electric F-150 - keep scrolling on that page, and look at the kind of depth and detail they get into: https://www.theautopian.com/the-2022-ford-lightning-is-just-...

The site is a gem.

I had the opportunity to design my own set of wheels with a friend for my Mustang GT. I put a thread together with photos of the process from start to finish, it was a lot of fun. I don't have the Mustang anymore, but the wheels are stacked in my garage awaiting a future project. https://www.mustang6g.com/forums/threads/arcane-stellar-–-a-...

One day, I believe car design regulations will be amended to allow fully electric braking (ie. no hydraulics, drums, rotors, or pads). At that point, the motor can be moved into the wheel (unsprung mass = bad, but weight savings from not needing an axle or gearbox will outweigh this). Suspension and steering design is then far easier, because there is no axle to need to keep straight.

Braking redundancy will be achieved by having motors/brakes on all four wheels, and within each motor 3 independant phase coils with independant controllers, such that there are effectively 12 brakes on a car. Normally the controllers work together for smooth braking, traction control, software differential, etc. But even after 3+ failures braking performance should still be satisfactory for an emergency stop.

Obviously braking energy needs to go somewhere. In the happy case, it's regen'ed into a battery. If the battery can't accept it, it gets dumped into dump resistors. If the dump resistors fail, it gets dumped into motor coils (of which there are 12 remember). Obviously the motor coils will heat up very fast, so this is probably a one-use-only failsafe, like airbags.

So the whole system (except the pedal itself) is 12 way redundant.

For comparison, here's the front suspension of a 1956 Buick:

http://buick.oldcarmanualproject.com/manuals/1956/1956%20Bui...

Observe that the kingpin axis is entirely inboard of the tire, almost vertical, and the scrub radius is such that the axis meets the ground inboard of the contact patch of the tire (in other words, it doesn't really "scrub" the tire when turning).

What stops the suspension from actually steering is the steering system itself and the hands of the driver holding the wheel. You can visualize that in the picture above or below; if the ground pushes the tire rearwards at the contact patch, which is a few millimeters outboard of where the kingpin axis intersects with the ground, that tire will have a tendency to rotate, which will pull on the steering tie rod and send forces to the steering wheel.

What isn't mentioned is that if you're braking, then the wheel on the other side also has the same force applied to it; only the difference between the two forces is what attempts to back-drive the steering system.

Note that it is harder with rack-and-pinion to approximate https://en.wikipedia.org/wiki/Ackermann_steering_geometry which is advantageous for tire wear.

Personally, I prefer the smoother and more isolated steering feel of a traditional recirculating-ball system, but then again, I'm not the type of driver who likes fast cornering.

This is a great example of the illusion of explanatory depth [1]

You read the title and think "D'oh obviously traction", then you see the first picture in the article and think "Yep, obviously flatter tyres because traction", then you read a little more and think "Wait, what do they mean by flat?", ...

... and then it just keeps going deeper and deeper into this rabbit hole you never considered before and barely even noticed. You realize you didn't know shit.

The explanation ends up being steering feedback forces. Now I wonder if we can have deeper wheels again with modern electric motor power steering.

[^1] https://thedecisionlab.com/biases/the-illusion-of-explanator...

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3062901/

> This is felt as kick-back to the driver and if it’s bad enough can rip the wheel out of your hands. Some of you may have had that experience in the past.

It can also break the driver's thumb, if the thumb is on the inside of the rim. If you're driving over rough terrain, you're well advised to keep your thumbs on the outside of the rim. This is true even at low speed. I once had to pull a car up onto a normal-sized curb and did so at low speed. Doing so definitely kicked the wheel.

What a great article! The world is absolutely full of things that are carefully designed around very real engineering constraints that almost none of us know about or ever notice. I always appreciate when a writer can bring me into a new world that I didn’t know anything about and show me the care and attention to detail that I would otherwise have never seen.

The flatness in this case is the outer surface of the aluminium rim. And as a rim enthusiast, I can agree that the modern flatness is less appealing than compared to those in the past.

I would have enjoyed this but didn't understand it. I think the main problem is that I didn't understand what they meant by tyres "being flat" so the rest of it was impossible to grok.

The timeline of this development exceeds the timeline of my own experiences since the 90's.

I've always driven cars with rack and pinion steering while wheels went from something like a typical 185-65x15 to 245-40x18. So, wheels are larger and the profile is much smaller (more rim and less rubber between the car and the road).

Higher power warrants bigger brakes and bigger brakes warrants larger rims but for the average car rims have grown way oversized. Many cars have the space to take rims that are 2-3 inches smaller than what comes as standard.

My anecdotal and average empirical results is that cars with wide rims and little rubber mostly seem to reduce comfort, increase noise, and make the steering very susceptible to unevenness, slopes and grooves of roads and layers of snow and ice and thus requiring constant steering response from the driver. I've had both kinds and the difference is huge, and exaggerated by bad road conditions that we find on our roads. On my older vehicles with a higher and narrower tyre profile I barely have to steer at all but just keep my hand relaxed on the wheel while the car ploughs pretty much through whatever in a direct line. Of course, I keep the wheel geometry of all my cars well-aligned so they shouldn't wander around.

in order to figure out what this article is saying, I have to learn a lot of terms, and I don't think it's going to be that astonishing or "aha!" so it doesn't seem worth it. The positive scrub ratio measured along the kingpin axis from the kingpin center... if only I knew what a deep dish wheel was as opposed to a flat wheel...

I’m going through this experiment myself. I have some et20 (+20mm offset wheels) in a car that had 45mm offset wheels from the factory. Meaning the wheel center is 25mm further out than stock. However, the new wheel is also wider, so is not all on one side.

The steering is definitely different, especially because I also have tires that are 3 inches wider than the factory ones. The car is harder to keep straight if the ground is uneven because it wants to pull in all sorts of directions. I also don’t like how at full lock the outer wheel drags on the ground. But at this width the closest I can get is an offset of +35mm, any higher and the wheel touches the control arm, and at 40 it would probably hit the springs.

Talking to some track guys seems like they are still faster with a wider track than with lower scrub and told me to not worry about it, but I still have my concerns.

Related question: Why must brakes be inside the wheels rather than inboard on the axle? Why not weld disks onto the axle inboard of the wheels and put the brakes there? That would make more room inside the wheels.

Of course on undriven front wheels it wouldn't work because there is no axle, but in front-wheel-drive cars there is one. The brakes could be inboard of the CV joint, no?

I can't really understand the author's (and apparently some designers') fetish about "deep dish" wheels. If a flat wheel allows better technical solutions and even improves aerodynamics, I'm all for flat wheels! Hell, even Formula 1 cars (which used to have the "deepest" wheels ever) use hubcaps since this season (https://the-race.com/formula-1/gary-anderson-how-f1s-new-whe...). Maybe that will make "flat wheels" sexy? We will have to wait and see...

Some cars have a virtual ball joint on the bottom of the hub to get around the ‘the brakes are in the way’ issue. Two separate arms with two more inboard ball joints act the same as one arm with the joint much further out.

https://en.m.wikipedia.org/wiki/Dual_ball_joint_suspension

I have a 1985 VW Vanagon camper. Mechanically, it's a POS with 99.9% NLA parts. It has 16" truck tires. Before that, it had properly weight-rated 14" trailer tires (the owner before had under-spec, unsafe passenger car tires on it.) The 16" are much easier to find and cheaper than the 14". Geometry-wise, the OD isn't excessively different that before because it's a massive, strong "pillow" between surfaces and the OD of rim. It's when you get to the point where you can't hop a curb at low speed without worrying about wrecking the rims that there's a problem with low profile tires. There always exists a high enough speed over a large enough obstacle that will cause mechanical damage to rims. If you want to drive a super car with perfect aerodynamics everyday, don't use driveways with any incline to them, don't get near to curbs, and don't drive anywhere with potholes.

The challenge is how much optimization for efficiency vs. durability vs. cost manufacturers want to or are ordered to sacrifice.

One question I've had: why are car brakes inside the wheel at all? Is it only ease of servicing? Putting the brake disks on the shaft before the suspension would make wheels lighter and allow positioning the kingpin much further out.

I tried to google for an explanation, but only found hits about brakes problems.

The Autopian is a great car site. It was set up by some Jalopnik writers (david tracy and jason torchinsky). As well as "normal" car articles they love techy/offbeat/unusual aspects of cars and aren't afraid to publish it.

I'm reading this article and the whole time I'm thinking, my 1998 Jeep Cherokee XJ has completely flat wheels, and then I get to the very bottom:

> [Editor’s Note: Not all designers prefer dished wheels. Some commenters were wondering why the Jeep JK/JL Wrangler, which has an old-school steering box instead of a rack and pinion setup, has such flat wheels. As far as I know, this is largely a styling decision. -DT].

So, it also applies the the XJ limited wheels too:

https://i.ibb.co/zfHMNbB/B03-FA738-777-A-40-D6-817-F-C0785-E...

OT but related to tire pressure.

There was this gem [1] posted in reddit the other day and I guess it is partly a failure of UI and inexperience.

A junior mechanic tried to fill the tires to "100%". https://i.redd.it/eu73w8earfn91.jpg

Edit: fixed, old reddit. App doesn't make old reddit links.

[1] https://old.reddit.com/r/Justrolledintotheshop/comments/xcdv...

To get more money repairing rim damage, obviously

I thought it'd be about reducing wear. Note that tyres are a massive air pollution contributor https://www.polytechnique-insights.com/en/columns/planet/are...

I'm usually a huge fan of engineering articles but this one isn't really accessible.

TL;DR: Wheels contain the brakes, so they need space inside for the brakes. Just inside the wheel is part of the steering pivot mechanism. Constraints around the optimal design of these systems prevent the classic 'domed' wheel construction.

Does anybody actually enjoy this type of type of SEO content?

Stuffed with filler words to the max. Maybe there is an answer to the title somewhere on the page. But the way it is written, it just stole my time until I gave up after a few paragraphs of filler content. First sentence:

    Have you ever wondered why designers show
    sketches of concept cars with massive deep dish wheels, but
    when those cars actually make it to production the wheels
    end up being fairly flat?

No. I just followed a link "Why car wheels are so flat these days" and was interested in the answer.

Compare that to a classic essay "A plan for spam" by Paul Graham:

http://paulgraham.com/spam.html

First sentence:

    I think it's possible to stop spam,
    and that content-based filters are the way to do it.

That's the type of content I would like to see on HN.

If it was 2022 style SEO content, PG's essay would have started with "Have you ever wondered why you get so much spam into your inbox these days and why that spam is so terribly boring, sprinkled with typos and ads, often full of images and links, and what you could do to get rid of it?". Shudder.

Given my OCD this drives me nuts because I can’t look at a wheel to get a sense if it’s low on air pressure anymore. I always get nervous thinking it’s gone flat and needs fixing.