silverelan

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An addition to your table: The Model Y Performance tires are 255 front/275 rear.
I am pretty sure that you can swap out from 225/55 to 235/50 tires on the factory rims and it'll be a pretty clean transition. It's just that nobody wants to get new tires on a brand new car.

The size of the brake rotors is probably not super important considering the amount of regenerative braking that is done which leaves much of the mechanical stopping redundant. The real problem is the contact patch of skinny tires for 5, 000lbs means less traction and it takes longer to stop.

From a side view angle the MME looks amazing with those factory rims.
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would 235/45 R18 work? I have a set of Michelin Energy tires that size.
 

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The size of the brake rotors is probably not super important considering the amount of regenerative braking that is done which leaves much of the mechanical stopping redundant.
Under most driving, that is true. However in several conditions that won't hold true. In a panic stop condition from above 45 mph, the rotor will possibly heat enough to make modulation difficult. Even with Anti-skid brakes, stopping distance will increase. Under any kind of spirited driving brake fade will quickly become a problem. Even the 12" rotors on the Y are only sufficient for street driving, under track conditions they'll overheat quickly. A Mach-e is as heavy as my Blazer (4900#) and the 11.6" rotors on that are insufficient for daily driving. One hard stop and they start to fade. A common solution is to replace the front brakes with the 12.5" 3/4 ton brakes. I did that and it made a world of difference. The truck went from unsafe to safe. IMHO, the 10" rotors on this vehicle are unsafe. Hopefully Ford engineers will reconsider this cost saving measure on production vehicles. I wouldn't even consider towing anything with these brakes. I'd be hard pressed to consider daily driving with a car that weighed more than 4000 pounds with these brakes. Like I said, my Blazer had better brakes than these and it was scary a lot of the time.

The real problem is the contact patch of skinny tires for 5, 000 lbs means less traction and it takes longer to stop.
Actually, the contact patch on a tire is dependant only on tire pressure and vehicle weight. I learned this after a lot of sand driving. Think about it this way. Let's say the E weighs 5000 pounds and weight is perfectly distributed. Each wheel carries 1250 pounds. If the tire pressure is 35 psi, we already know the contact patch: 1250/35=35.7. The contact patch is 35.7 square inches. It's pretty simple physics. Note that we didn't talk about tire width; it's irrelevant.

That said, wider tires have been shown countless times to reduce braking distance. Technically, the physics don't account for that. It should just be braking coefficient and weight. I've seen two explanations that make sense to me. One, tire manufacturers make wider tires with softer rubber, increasing the coefficient of friction. I have no idea if that's true, but it was an engineer for a tire company that told me that. He could have been pulling my leg, but he seemed serious. He then went on to give reason #2 that seems more logical to me. In a panic stop the tire heats up and erodes. Makes senses. That erosion of the tire takes the form of both gas and micro particles that basically lubricate the portion of the contact patch behind the leading edge. Since a skinny tire has a long narrow contact patch, that lubrication has more effect than a wide short contact patch would see. That's what he said; it makes sense to me. I certainly wouldn't take offense if a tire engineer wants to improve on that explanation.

From a side view angle the MME looks amazing with those factory rims.
Absolutely. One of the very few factory rims I've seen that I wouldn't want to change out.
 

silverelan

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Under most driving, that is true. However in several conditions that won't hold true. In a panic stop condition from above 45 mph, the rotor will possibly heat enough to make modulation difficult. Even with Anti-skid brakes, stopping distance will increase. Under any kind of spirited driving brake fade will quickly become a problem. Even the 12" rotors on the Y are only sufficient for street driving, under track conditions they'll overheat quickly. A Mach-e is as heavy as my Blazer (4900#) and the 11.6" rotors on that are insufficient for daily driving. One hard stop and they start to fade. A common solution is to replace the front brakes with the 12.5" 3/4 ton brakes. I did that and it made a world of difference. The truck went from unsafe to safe. IMHO, the 10" rotors on this vehicle are unsafe. Hopefully Ford engineers will reconsider this cost saving measure on production vehicles. I wouldn't even consider towing anything with these brakes. I'd be hard pressed to consider daily driving with a car that weighed more than 4000 pounds with these brakes. Like I said, my Blazer had better brakes than these and it was scary a lot of the time.


Actually, the contact patch on a tire is dependant only on tire pressure and vehicle weight. I learned this after a lot of sand driving. Think about it this way. Let's say the E weighs 5000 pounds and weight is perfectly distributed. Each wheel carries 1250 pounds. If the tire pressure is 35 psi, we already know the contact patch: 1250/35=35.7. The contact patch is 35.7 square inches. It's pretty simple physics. Note that we didn't talk about tire width; it's irrelevant.

That said, wider tires have been shown countless times to reduce braking distance. Technically, the physics don't account for that. It should just be braking coefficient and weight. I've seen two explanations that make sense to me. One, tire manufacturers make wider tires with softer rubber, increasing the coefficient of friction. I have no idea if that's true, but it was an engineer for a tire company that told me that. He could have been pulling my leg, but he seemed serious. He then went on to give reason #2 that seems more logical to me. In a panic stop the tire heats up and erodes. Makes senses. That erosion of the tire takes the form of both gas and micro particles that basically lubricate the portion of the contact patch behind the leading edge. Since a skinny tire has a long narrow contact patch, that lubrication has more effect than a wide short contact patch would see. That's what he said; it makes sense to me. I certainly wouldn't take offense if a tire engineer wants to improve on that explanation.


Absolutely. One of the very few factory rims I've seen that I wouldn't want to change out.
Thanks for the insight! I love being wrong and learning something new.

Here's a quick write-up from Road & Track saying the same thing you did. I went down quite the rabbit hole unlearning what I thought I knew. Long story short, a wider tire gives you slightly better cornering grip but if you want a bigger contact patch, you need a bigger wheel.

So now I'm just left with disliking the tires simply cuz they look a bit goofy but that's on me.

Much appreciated! :)
 


RunningHorse

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You are confusing rotor and rim size. Seriously, you are joking, right? 12" rotors tiny? Come on, you're pulling my leg. Nobody is that... OK, do you know anything at all about cars??? BTW, I'm not comparing apples to oranges. The base Y has 12" rotors with 255 wide tires with a load rating of 104, that Mach-e in the pictures above has 10" rotors and 225 wide tires with a load rating of 103. If you think that those brakes and those tires will provide superior stopping power you are sadly mistaken.
No I'm not confusing rotor for rim size. You're either trolling or reading comprehension is at 3rd grade level.. Ford already released official specs, see the link below and scroll down to brakes. 18" front/17" rear are the base model rotor size. Th model y has small rotors for its weight and wheel size.


https://www.ford.com/cmslibs/conten...-2/pdf/seo-pdfs/Mustang-Mach-E-Tech-Specs.pdf
You are confusing rotor and rim size. Seriously, you are joking, right? 12" rotors tiny? Come on, you're pulling my leg. Nobody is that... OK, do you know anything at all about cars??? BTW, I'm not comparing apples to oranges. The base Y has 12" rotors with 255 wide tires with a load rating of 104, that Mach-e in the pictures above has 10" rotors and 225 wide tires with a load rating of 103. If you think that those brakes and those tires will provide superior stopping power you are sadly mistaken.
Here is the spec sheet ford released. Scroll down to brakes

https://www.ford.com/cmslibs/conten...-2/pdf/seo-pdfs/Mustang-Mach-E-Tech-Specs.pdf
 

Nak

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No I'm not confusing rotor for rim size. You're either trolling or reading comprehension is at 3rd grade level.. Ford already released official specs, see the link below and scroll down to brakes. 18" front/17" rear are the base model rotor size. Th model y has small rotors for its weight and wheel size.


https://www.ford.com/cmslibs/conten...-2/pdf/seo-pdfs/Mustang-Mach-E-Tech-Specs.pdf


Here is the spec sheet ford released. Scroll down to brakes

https://www.ford.com/cmslibs/conten...-2/pdf/seo-pdfs/Mustang-Mach-E-Tech-Specs.pdf
Dude, you're embarrassing yourself. Think about it for a second, how could you possibly fit an 18" rotor inside of a 19" rim? You've obviously never worked on a car. A 3/4 ton pickup has 12.5" rotors. (At least mid '90s K2500s did.) Do you know what a 3/4 ton pickup is? I'll make it even easier for you. Look at the pictures at the beginning of this thread. Look at the markings on the tire. It's a 19" wheel. look at the rotor inside the wheel. Even a genius such as yourself should be able to figure out that the rotor there is just about 10" in diameter. You're right about that spec sheet saying what it does. It's obviously wrong. Duh. The first variant shows an 18" wheel and 18" brakes. you do know that's not possible, right? You know, the whole two objects can't occupy the same space thing? Physics not your strong point I guess? Maybe try geometry? A tape measure? You can operate that, right? Seriously, give it a go. They're not that bad.

Yeah, you're right. Someone here is definitely a troll. Nobody is that... Goodbye now.
 
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Nak

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Thanks for the insight! I love being wrong and learning something new.

Here's a quick write-up from Road & Track saying the same thing you did. I went down quite the rabbit hole unlearning what I thought I knew. Long story short, a wider tire gives you slightly better cornering grip but if you want a bigger contact patch, you need a bigger wheel.

So now I'm just left with disliking the tires simply cuz they look a bit goofy but that's on me.

Much appreciated! :)
No worries. I love learning new things too. It keeps your brain young. :) I've been building cars and four wheeling for 45 years, and I just learned this tid bit last year. I should have figured it out years ago, the physics involved is pretty simple. I just never analyzed it. It's amazing what the mind can overlook when you assume you already know the answer.

I think that R&T article has an error though. Tire diameter shouldn't make a difference. At a set air pressure the physics tells you what the contact patch has to be. You have to offset that though by tire construction I guess. A stiff enough sidewall should be bearing some of the weight. So tire construction makes a difference too. With a run flat tire you could have zero pressure and not increase the size of the contact patch by too much. That makes me wonder... Take two identical construction tires. One wide and one narrow. The narrow tire sidewalls would support each other more, taking more of the car's weight and decreasing the contact patch size? Any tire engineers out there?
 

RidetheLightning

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Send us a photo of your MME touch screen after your first week of usage. Don't clean the screen before sharing those photos. :)
Hahaha you should see my wifeā€™s iPad and iPhone. All that girly hand lotion makes for greasy screens
 

silverelan

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Dude, you're embarrassing yourself. Think about it for a second, how could you possibly fit an 18" rotor inside of a 19" rim? You've obviously never worked on a car. A 3/4 ton pickup has 12.5" rotors. (At least mid '90s K2500s did.) Do you know what a 3/4 ton pickup is? I'll make it even easier for you. Look at the pictures at the beginning of this thread. Look at the markings on the tire. It's a 19" wheel. look at the rotor inside the wheel. Even a genius such as yourself should be able to figure out that the rotor there is just about 10" in diameter. You're right about that spec sheet saying what it does. It's obviously wrong. Duh. The first variant shows an 18" wheel and 18" brakes. you do know that's not possible, right? You know, the whole two objects can't occupy the same space thing? Physics not your strong point I guess? Maybe try geometry? A tape measure? You can operate that, right? Seriously, give it a go. They're not that bad.

Yeah, you're right. Someone here is definitely a troll. Nobody is that... Goodbye now.
I dunno about the brake rotors just 10". Seems like an odd thing for Ford to be very specific about yet wrong on across the entire lineup, no?

I mean, the rotors look bigger than 10" across to me in this photo.

Ford Mustang Mach-E Ruby Red EX Mach-E (White interior) in the wild-revealed 1D016D6E-7560-4759-85F9-74AD99949AFE
 
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I dunno about the brake rotors just 10". Seems like an odd thing for Ford to be very specific about yet wrong on across the entire lineup, no?

I mean, the rotors look bigger than 10" across to me in this photo.

I imported this photo into my CAD program, set the rim diameter to 19" and measured the rotor diameter at 10". The picture was included in the original thread on TMC, and initially I did not notice that the OP chose not to include that photo here.

The numbers on that Mach-e spec sheet are clearly wrong. First, it is not physically possible to have an 18" rotor with an 18" or even a 19" rim. There must be room for the caliper. Second, the largest brakes EVER on a production vehicle are on the Lamborghini Urus and measure 440 mm--17.3". Even the mighty Mustang GT500 is equipped with massive 420 mm brake rotors--16.5". And that requires 20" wheels. Interestingly, Ford seems to have an issue with getting their specs right on the GT500 as well. Look at this page, they correctly list the 420 mm rotors, but list them as 15.5" in diameter. 420 mm is 16.5". GT500 specs.

It would be absolutely incredible if Ford offered the 16.5" rotors on the Mach-e GT, but I seriously, seriously doubt it will happen. 13" would be stunning for a production car, 12" would be excellent as long as you didn't want to track the car for more than a few laps. 10" rotors on a car like the Mach-e are insufficient and fans should make sure that Ford knows that fans care that the Mach-e lives up to it's potential. It's simple physics; 10" rotors are neither sufficient nor safe for a 5000 pound car with the performance capability of the Mach-e. Did you ever see an early six cylinder Mustang with a V-8 engine swap where they neglected to upgrade the brakes? I drove one and it was an accident waiting to happen. Same thing here.

EDITED TO ADD: I added a photo of a Model Y 21" wheel with 12" rotors for a visual reference for those without a CAD program. Remember to bear in mind that the E rims are 19" and the Y rims are 21". These pictures also highlight another disturbing point about the E brakes. Look at the relative size of the calipers. The E calipers simply are too small for a car that weighs 600 pounds more than the Y. Granted, the Y pictured below is the performance version, but the only differences in brakes between that and the base model are slightly thinner pads and rotors on the base.

Ford Mustang Mach-E Ruby Red EX Mach-E (White interior) in the wild-revealed MVIMG_20200616_184455 - Copy


Ford Mustang Mach-E Ruby Red EX Mach-E (White interior) in the wild-revealed 20200705_115557
 
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I imported this photo into my CAD program, set the rim diameter to 19" and measured the rotor diameter at 10". The picture was included in the original thread on TMC, and initially I did not notice that the OP chose not to include that photo here.

The numbers on that Mach-e spec sheet are clearly wrong. First, it is not physically possible to have an 18" rotor with an 18" or even a 19" rim. There must be room for the caliper. Second, the largest brakes EVER on a production vehicle are on the Lamborghini Urus and measure 440 mm--17.3". Even the mighty Mustang GT500 is equipped with massive 420 mm brake rotors--16.5". And that requires 20" wheels. Interestingly, Ford seems to have an issue with getting their specs right on the GT500 as well. Look at this page, they correctly list the 420 mm rotors, but list them as 15.5" in diameter. 420 mm is 16.5". GT500 specs.

It would be absolutely incredible if Ford offered the 16.5" rotors on the Mach-e GT, but I seriously, seriously doubt it will happen. 13" would be stunning for a production car, 12" would be excellent as long as you didn't want to track the car for more than a few laps. 10" rotors on a car like the Mach-e are insufficient and fans should make sure that Ford knows that fans care that the Mach-e lives up to it's potential. It's simple physics; 10" rotors are neither sufficient nor safe for a 5000 pound car with the performance capability of the Mach-e. Did you ever see an early six cylinder Mustang with a V-8 engine swap where they neglected to upgrade the brakes? I drove one and it was an accident waiting to happen. Same thing here.

MVIMG_20200616_184455 - Copy.jpg
But the Mach-E is not an ICE vehicle. You cannot totally discount the power of the regenerative braking. I think the regen will be more than enough to compensate for the ā€˜too smallā€™ size of the rotors. With one pedal driving you may not need to even use the mechanical brakes. Iā€™ve heard in one video that the regen in unbridled mode feels like a gear kick down, so itā€™s got to be pretty strong. I would think that the regen would work in tandem with the mechanical brakes if you pressed on the brakes hard. Working together will be more than enough to safely stop the vehicle.
 

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I just want to add, I am not trying to put down the Mach-e. I have made it abundantly clear in my posts here that I am a fan and am hoping to see a car that will rival and exceed the Y. If it does that, then Tesla will make the Y better and so on. That's competition and in this case is good for fans of both cars and good for the planet as well.

What I am trying to do is point out an obvious and serious flaw that I hope will be fixed prior to full production. We all know that Ford engineers and product managers are reading this forum. If the fans do not accept serious flaws like the brakes pictured in this thread, Ford will likely take note and hopefully fix them. If you all just decide anything Ford gives you is wonderful then you are merely encouraging Ford to produce an inferior product. In the end, that will not be good for the Mach-e, for Ford, or for the Planet.
 
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Nak

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But the Mach-E is not an ICE vehicle. You cannot totally discount the power of the regenerative braking. I think the regen will be more than enough to compensate for the ā€˜too smallā€™ size of the rotors. With one pedal driving you may not need to even use the mechanical brakes. Iā€™ve heard in one video that the regen in unbridled mode feels like a gear kick down, so itā€™s got to be pretty strong. I would think that the regen would work in tandem with the mechanical brakes if you pressed on the brakes hard. Working together will be more than enough to safely stop the vehicle.
Yes I can discount regenerative braking. It will not be enough to compensate for the inferior brakes and calipers in a number of situations. Yes, the brakes are large enough that in most driving conditions they'll work fine. Regen will do most of the work and the wear will be trivial. HOWEVER, brakes need to be sufficient ALL of the time. They don't need to handle track day, that's what aftermarket brakes are for. But they do need to handle a fully loaded car in an emergency stop even after they have been used hard a few times. These brakes will not do that. The rotors are not large enough to absorb and disperse the energy involved. That won't happen often, but it likely will happen, at least once or twice. Is crashing just once because of inadequate brakes OK?

I drive a car that is 600 pounds lighter than the E. I have regenerative braking too. I have 12" brake rotors and they are enough to be safe. No more. I can drive a fun road and have enough brakes. Enough, no more. You have to understand an EV like the Mach-e is capable of repeated acceleration with alarming ease. The brakes need to match that capability. The Mustang GT is slower than the Mach-e. It's lighter than the Mach-e. And it's brakes are vastly superior to the Mach-e.

It always amazes me when hobbyists build a fast car with inferior brakes. All that matters to them is the power. It's the mark of a builder that has no F*&#ing clue. It's the same exact thing here, except that Ford has a clue, they're just being cheap because they must figure they can get away with it. Disabuse them of that notion now, don't tell them you'll accept crap.

You can make excuses for sub par brakes, or you can demand that Ford builds the Mach-e right.
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