Agreed…This is absolutely true. My Alpina B8 wheels (21-inch) are known to be more rigid yet just as light as the standard 20-inch wheels that BMW offers for other 8-series models. On top of that, the car is significantly more comfortable than other 8-series cars with 20” (like so much better in terms of comfort) .Reason being, as long as the car is designed for a larger tire, comfort won’t be compromised when staying within the 20-21-inch wheel range for larger sedans. However, it’s a different story if a manufacturer designs the car around a maximum tire size of 19 inches, and the owner wants to try 21-inch wheels that are not OEM wheels. Right now most large sedans are already designed with large 20-21” in mind. Looks great, and still comfy.

 

In regards to wheels, there is a happy medium. On your 7 the wheel sizes really don't have much of an impact on the ride, and on the W223 they really don't as much either (I havent driven it on the 21s but the 19s and 20s ride about the same), on the 222 though there was a big difference. My 223 has the 19s but that was just luck of the draw, I wanted the 20s but refused to buy one with the 21s.

As for the door handles, on your Tesla they worked well. Thats the issue, on the W223 they dont work well. I've said it before but my daughter is actually afraid to use the door handles because they've closed on her hands before. They haven't hurt her...but they shouldn't close on your hands.

 

I don't think I'm taking it too far at all.
Before I make my point, I am all for better looking larger wheels. Just take a look at what kind of wheels I have on my S.
That being said, the larger wheels options offered on almost all models/trims nowadays are heavier than the smaller wheels UNLESS the larger wheel option is forged.
I've had aftermarket wheels on ALL my cars (except for a Genesis sedan back in 2010) since '02.
From my experience, larger wheels set is always heavier than the smaller wheels set given the following conditions:
- Same dimension, as in overall diameter (including tires) and width (wider wheels are heavier obviously)
- Same design/spoke and construction (mono forged, 2-piece, 3-piece, etc.)
- Same manufacturing method (cast, forged)

Weight is ALWAYS bad on a vehicle when it comes to performance and efficiency.
Unsprung weight affects more negatively than sprung weight in terms of ride quality/driving dynamics.

You say the car's suspension was tuned with larger wheel diameters in mind... imagine having smaller diameter- lighter wheels on that suspension setup.
There's no denying ride comfort is compromised, to a varying degree, when the wheel size increases and tire's side wall height decreases.
It's just simple physics. Wheels/tires not absorbing road impacts mean it has to be absorbed by the chassis/suspension.

And let's be honest, better grip and handling? We're no race car drivers taking advantage of this on public roads.
One thing that WILL be noticeable though, is poor MPG. Wider tires mean more rolling resistance = poor gas mileage.
Again, simple physics.

Now, will I still put on larger diameter aftermarket wheels knowing all this performance disadvantages?
Absolutely.
I'm willing to sacrifice some ride comfort, performance, and gas mileage for a cool looking set of wheels.
But I'm making the decision knowingly and I do not kid myself by saying bigger wheels are better. They're NOT.

 

I will say, my S560 had staggered 19s and my S580 has square 19s. Outside of the better looks of the staggered wheels, I much prefer the square setup. They can be rotated, they are better in the snow (the wide rear tires hurt traction in the snow), tires are cheaper, way more tires are available. Just not a car that *needs* staggered wheels IMO

 

While they may be lighter than cheaper (read less well constructed) wheels in a smaller diameter as Dima said, that is not an apples to apples comparison. If you compare the same wheel in smaller sizing, the smaller wheel will always perform better in every measurable metric. It's not just the usual performance numbers either; you will have better economy/range, more traction, increased compliance, they are less susceptible to road hazards, and have less acoustic transmission into the car. OEM's use tech to partially overcome the losses in many respects, but you can never make par compared to a smaller wheel of the same construction. You have moved the moment of inertia further from the center of rotation, every tick up in size, also ticks up the weight of the wheel/tire combo; and you can't make the applicable physics go away when you start rotating that mass. In order to get lower profile tires to survive, the sidewall must necessarily be stiffened; this leads to less road conformity and your loss of traction. Lastly, it takes more energy to overcome the losses from upsizing wheels, and that's where your range/economy and performance is lost.

There is of course one benefit; the aesthetics, which is obviously a subjective. I'm not immune to it, and were I to purchase an i7, I'd get the rather tasty looking 20s in the split 5 spoke. I've run 20s a number of times and had no issue; but I don't tell myself they perform better; I'm just willing to accept the downside for the (my opinion) better appearance.

 

What? Physics based assessments vs subjective opinions? What is this forum coming to?

 

Weight, which can also be expressed in downforce, does increase performance in maneuvering and acceleration.

 

can we put it to rest?

The Science of Grip and Performance

The fundamental advantage of wider tires lies in the increased size of the contact patch—the area of the tire that is in direct contact with the road at any given moment. A larger contact patch allows for a greater distribution of the forces acting on the car.

Enhanced Traction and Acceleration

A wider tire provides a larger surface area for the force of friction to act upon. This increased friction translates to better grip, or traction. During acceleration, a vehicle's engine generates torque that is transferred to the wheels. For a car to accelerate effectively, the tires must be able to transmit this force to the road without slipping. A wider contact patch allows for more of the tire's rubber to engage with the road surface, increasing the total frictional force and enabling the car to put down more power without spinning its wheels. This is particularly noticeable in high-horsepower vehicles.

Improved Cornering and Handling

When a car turns, the tires must generate lateral (sideways) force to counteract the centrifugal force that is pushing the car outwards. A wider tire's larger contact patch provides more grip for cornering. This results in a smaller slip angle, which is the angle between the direction a wheel is pointing and the direction it's actually traveling. A smaller slip angle means the tire is deforming less and responding more directly to steering inputs, leading to a more stable and planted feel, especially at higher speeds. This enhanced lateral grip increases the car's cornering capabilities and overall handling precision.

Superior Braking

The same principle of increased friction applies to braking. To slow down, the brakes create a stopping force that the tires must transfer to the road. A larger contact patch allows for a greater braking force to be applied before the tires lose traction and begin to skid. This can result in shorter braking distances, a critical safety advantage.

 

With wder Dima, the same applies: Take that same wider wheel/tire combo, vs the smaller diameter wheel of the same construction, AND in the same width, you'll always suffer greater losses, as stated above. Physics is a ****.

As to downforce, yeah, totally works but this is conflating two different things. Downforce is generated using aerodynamic components to create a downward force that pushes the car onto the road, weight as considered here is gravity acting on the car's mass; they are not the same thing. More weight will always reduce total performance because weight will increase grip, but the grip to weight ratio goes down. That's lateral acceleration, acceleration, and braking, all get worse.

 

[QUOTE=crabman;9214983]With wder Dima, the same applies: Take that same wider wheel/tire combo, vs the smaller diameter wheel of the same construction, AND in the same width, you'll always suffer greater losses, as stated above. Physics is a ****.
You've hit on two crucial aspects of vehicle dynamics that often get overlooked. Excellent points, crabman (did your wife help you?)

1. Rotational Inertia is a Killer

Your point about wheel diameter is spot on. It's a classic trade-off between aesthetics and physics. While wider tires increase the contact patch, increasing the diameter dramatically increases rotational inertia. Because inertia scales with the square of the radius (I≈mr2), a larger diameter wheel requires significantly more torque to spin up and slow down. This directly hurts a car's effective acceleration and braking, often more than people realize. It's a perfect example of why "bigger" isn't always better in performance engineering.

2. The Critical Difference Between Weight and Downforce aerodynamic downforce vs static weight on a car

This is a fantastic clarification. Conflating static weight with aerodynamic downforce is a common mistake.

• Static Weight (Mass): As you said, adding mass is almost always a net negative for performance. While it increases the normal force on the tires, it also increases the inertia the entire car has to overcome—for accelerating, braking, and cornering. The grip-to-weight ratio inevitably gets worse.
  
• Downforce: This is the "magic" solution because it adds that valuable normal force without adding mass. You get the enhanced grip to push harder through corners without the penalty of having more mass to lug around.

Ultimately, you're correct. A truly optimized setup considers the entire system: tire width, compound, overall diameter, unsprung weight, and the difference between "good" vertical force (downforce) and "bad" vertical force (mass).

 

Nah, while not nearly so much, I also went to school. Although I would say I've forgotten a lot, been 45 years. Let her start talking about large data sets, statistics, models, her thing... That's where I quickly start seeing I'm out of my depth.

I'm not against bigger diameter wheels, it's not as if they kicked sand in my face and left with my girl. But performance, that's a loss when compared fairly. I do get that people might want to make that compromise; I'm one that has, and might again.

 

Weight, depending on its location can have a positive effect on performance.
Top fuel dragsters used to mount the heaviest component(the engine) in front of the driver.
Performance in top fuel dragsters was increased significantly, when the extra weight over the rear wheels resulted from placing the engine behind the driver.
Pickup trucks, with empty beds, suffer from poor traction.
Loading sandbags, or other heavy weight in the bed increases traction and minimizes slippage when the coefficient is high or low.
When it comes to traction, only 2 variables have an effect, coefficient of drag, and the normal force.

 

Grip to weight ratio can be hard to grasp. Your examples do not disprove the well known physics involved, but instead highlights a few other related aspects in a process that is not quite so simple as it seems.

In your truck example, you are both redistributing weight and adding weight. The truck's total grip to weight ratio becomes worse because of the added mass, but the local grip to weight ratio at the drive wheels goes up, which is what helps you get traction on a low-friction surface.The same is true for the dragster. Performance increased from moving more of the engine's weight to the rear drive wheels, which improved the local grip to weight on the motive tires. The overall grip to weight ratio did not improve; but performance is gained with the weight redistribution.

All of that, however, is way out of context with our original discussion. We were talking about the losses that come from running larger-diameter wheels with lower-aspect-ratio tires. Going back to that, even in your purposely extreme examples, you'll see those same losses there as well.

Lastly, you probably meant to say coefficient of friction, not drag.

 

Yes. You are correct. I was mistaken for saying drag. For some reason my mind landed on dragsters, and dragging tires across the pavement. But for sure I should have said coefficient of friction.
If my reply is too far afield of the topic, I ask all to please pardon me.

 

No worries for my part. You got me thinking about where the term drag race comes from, the drag part I mean. So I looked it up because I know Stream would want me to take his thread as far afield as possible Copy/paste follows...

That connection comes in the 18th century, by which time smaller drags/drays were being used for the hawking of goods, and the poor souls who hauled them around had the ingenious idea of adding wheels. Samuel Johnson defined such a vehicle in A dictionary of the English Language, 1755:
Drag … Somewhat like a low car: it is used for the carriage of timber, and then is drawn by the handle by two or more men.
Before long, the term ‘drag’ came to be used for the thoroughfares along which drags were trundled. The poor get in on the act again (they are always with us, after all) in Henry Mayhew’s London Labour and the London Poor, 1851:
Another woman… whose husband has got a month for “griddling in the main drag” (singing in the high street).
The ‘roadway’ meaning of drag was transferred from England to the USA and, in the 1950s, the teenage pastime of racing cars ‘along the main drag’ began to be called ‘hot rodding’ or ‘drag racing’. There are also references to dog drag races in publications throughout the 20th century, but the earliest that explicitly mention cars come from from the 1950s. An example of that comes in this heartfelt piece from The Southeast Missourian newspaper in June 1950, titled Teenage Crime:
“There have been entirely to many hot rod exhibitions of fender tagging and drag racing.
Before long the street pastime became a sport, first taking place on disused airstrips and later on purpose-built drag strips, the US National Hot Rod Association being formed in 1951. So, the link to the original meaning of drag is almost lost – drag racing is no longer done with or on drags and nothing is dragged along.

 

Interesting.

Tractor pulls literally drag a weighted box with a bulldozer style blade attached on a dirt track nominally 300’ long. So in essence it has all the elements of a drag strip, main drag, drag dray, with the benefit of having something that is actually being dragged!

 

Where I live, with full service car washes close to the $50 mark with tip these days—along with the less than acceptable wipe down work—I have been running my I7 through one of these Express 5 places. The car comes out nice, it’s quick and doing the wipe down & vacuuming myself gives this old guy a bit more needed exercise. One thing that makes this darn near enjoyable, is the fact that the wheels NEVER get dirty from brake dust, due to the “one pedal” regenerative driving I do. Honestly, wiping down each wheel takes like ten seconds and they look like new. Another great benefit of an EV.

The other day, I had a very busy schedule, with multiple appointments which were reasonable distances from each other and I found myself driving a bit more aggressively than I normally do. This is another area where the I7 with the Autobahn Pkg. REALLY shines. This massive saloon drives SO much “smaller” than it is and the handling is just out of this world! You can throw this SIX THOUSAND POUND car into sharp curves and it’s like the thing is on rails. The only other big vehicles I had that would rival this type of handling were my W222’s with MBC. The S Class cars without MBC or the earlier ABC, would fail miserably in a skid pad matchup against my I7.

I have come to absolutely love the ride quality of my I7 and have developed a great appreciation for The Ultimate Driving Machine. If you haven’t at least test driven one, you should.

My favorite parking space in Corona Del Mar, CA.

 

So I got a chance to check out the i7 up close and personal at a BMW dealer while getting a gallon of coolant from the parts department.

It was wearing a gorgeous bluish grey paint with ivory interior.
I sat in the rear seat and the driver’s, played around with the buttons and auto open/close doors.
Felt the material inside and examined the fit and finish on this thing and I gotta say,
I was really impressed with the overall quality.
I mean, BMW is no slouch when it comes to fit and finish but I never quite got passed the fugly face of the i7
But the interior just blows everything else out of the water.
I have to admit that I like it better than my S580.

After playing around with the interior, the exterior didn’t seem half bad with the beautiful paint, larger wheels and the lighted grill
I’m definitely warming up to the ugly front and the chunky front end/proportion.

It was the xDrive60 model, loaded with a sticker below $140k.
There was a black 760i on my way out and that one looked sharp.
Wait, did I say sharp? Lol
Crazy how you get used to the ‘ugliness’, eh?

 

Thanks for sharing, bmw probably took some inspiration from their Rolls-Royce.

 

It’s the way the I7 drives! I am so smitten by the quietness and smoothness that I really don’t even notice the looks anymore.

 

I see how you were disappointed with MB with repeated, unfortunate issues you had with the S class.
Even with the polarizing looks of the new 7er, I can understand that it’s a great alternative when shopping around for a luxury sedan.
And I can’t blame you for choosing the 7, as it’s a wonderful vehicle on the inside.
I can’t vouch for how it drives but from the experiences I’ve had with BMW products, I’m sure it drives wonderfully.

 

It’s a great vehicle and I really like it a lot, definitely better than the S580 inside. But…I just couldn’t with the styling. Too much work to convince myself to like it for this kind of money.

 

In fact, the critical consensus regarding the exterior front-end is often an online or reviewers type of thing, especially like here in Mbworld or other online avenues. Outside the online world, the real-life feedback is overwhelmingly positive, and most owners, or those who had it for some time, would tell you it is even more positive than any other nice car they drove. I think the sales numbers reflect the opinion of most people around as a measurable fact than just being my opinion whether good or bad. As an owner of an all-black exterior i7, the feedback is more positive than any other car I had. Now to me personally, If I see white or grey 7 with M-Sport, I'd join the online consensus as I myself isn't convinced about that M+white combo yet and will probably never because of the contrastic smiley gloss-black shape (but even then, I'd be among the minority as far as real-world feedback). Otherwise, my all-dark exterior 7 with no contrasting exterior receives very positive feedback and I personally love it so much just as most people around me.

As for the interior, just as you've experienced, it's the best interior I ever sat in and the attention to detail and build quality are incredible. But that's not why I love this car. My Alpina B8 interior was fine but boring and I still loved that car so much because of how it drives. The 7 has a perfect interior, and it also drives like a dream, and the later is exactly why am so impressed with this car for now and just can't for the first time ever even think about a good trade in plan or what's next for me. Only time will tell if this is true as my average has been 1 year per car for over a decade now. Everything else at this price point will feel like a downgrade for me as a driver. It honestly exceeds what I expected at this price point, and I think that's the issue the competitors need to figure out to compete, if they care. This is a Rolls-Royce level with a BMW badge and those who co-own a Spectre or another RR shared the same feedback.

 

The thing is, its polarizing. Some people love it. others HATE it. For me something so polarizing doesn't do it for me when spending this kind of money.

 

I get that, but at the same time I can only judge it by what people around me are saying/sharing. Assuming that I spend my money based on what people think (which I don't), even then I will not give too much weight to about a dozen or less of forum users and youtuber on the web. There are several other models around that seems to get some hate on specific websites or forums just because of the competition or loyalty aspect (e.g.: X7 owners are always trolling XM owners), wherein the fans and majority of people around really like it. In real-world, my experience just like everyone's experience including yours is: everyone around me talked about how much they liked it. I am yet to see the opposite at all. That doesn't mean, however, that I don't have my own opinions about whether I like it or don't... I am just referring to what the majority of people in the real-world seem to think about the car, and this part seems to be overwhelmingly positive.