Starter

I've followed some of the discussion in a couple of threads on brakes and thought everyone might want some more info. There is an article in the latest Sportscar (Sports Car Club of America's monthly mag.) about braking systems.

The article is more oriented toward racing applications, but does discuss street use. A number of industry experts were quoted and it was specifically mentioned that drilled rotors provide NO benefit. To the contrary, it makes the rotors much more fragile. Drilled rotors were originally used in racing to dissipate boundry layer gases caused by asbestos pads - asbestos pads are do longer are used by anyone. Although modern pads do create some boundry layer gases, they are not as significant as asbestos and are not much of a factor in racing, almost nonexistant on the street. Slotted rotors do provide some benefit and may be worth the extra cost.

Very good article, if you can find a copy, read it.

EricL

I'm sure there is some good info in there. I'll try to grab a copy.

If you x-drill a rotor, you reduce the thermal mass. It creates a trade-off. The lower thermal mass means the rotor will heat up quicker and cool down slower with all things being equal. Porsche are not idiots, and they still x-dirll their brakes. Brembo are not idiots and they still x-drill their brakes.

Granted, there are a number of makers of very high-performance brake systems. And if you look in Race Car Engineering, you'll find brakes for racing cars with slots only too.

The boundary air issue is only one of many issues that impacts brake design. And, while the bulk of the air is pumped by the internal vanes in vented rotors, you do get increase the total surface area for metal-to-air cooling.

So, Brembo does it, Porsche does it and here is a link that might interest some:

Hurricane Fin Cooled Rotor

Notice the cross drilling and notice the interesting design that increases transfer area (think IC/transistor/electronic heat sink)


Different view of the brake rotor

1killercls

Good stuff ERIC!!!

azian21485

reducing thermal mass isn't what you want..it'll cause fade and wear out your pads like crazy...like you said..the drilled rotors will heat up faster and stay heated up...being at such high temperatures at a long period of time will cause the pads to "fade" and will produce lots of wear

the reason blanks are better is because since they have more surface area and mass, they are able to absorb the heat..this keeps heat away from the space between the rotors and the pads...pads won't get hot so they won't fade...with the rotors having more mass they dissipate the hot air through the vents (assuming you have vented rotors..but who doesn't?)

EricL

First, if you’re talking about the surface area only on the FACES of the rotor (inside and outside), then yes, you have less surface area on the rotor FACES. However, you need to consider the area gained or lost over the whole rotor. When the rotors are x-drilled, you have removed the area from the rotor’s FACE, but have increased the area in the actual hole. So, the surface area is dropped by Pi * R^2 (the face of the hole) and the surface area added by the cylinder of the hold is: depth_of_hole * Pi * R^2. And, to be fair, you’d need to multiply the Pi * R^2 by TWO to account for the surface area lost by drilling. (This accounts for the areas removed on the outside FACES of the rotor, and the sides removed on the inside near the internal venting fins). This tidbit of "math" only accomplishes one task, and that is to find out how much surface area you have gained or lost, and doesn’t account for the increased air flow that will come from the “pumping action” on the inside of the rotor. (It also doesn't account for other issues... keep going.)


And, here is a picture of the Porsche ceramic brake:



Notice that it has cross-drilled holes in it!

And, here is a picture of a F1 carbon brake:



Notice that is doesn't have any cross-drilled holes in it!

It depends... hey? The F1 guys are not stupid and the Porsche folks aren't stupid either!

F1 cars have huge brake ducts and carbon brakes. The internal vents are already doing to bulk of the work.

If you have minimal air moving through the disks (slow speed, etc), you want more metal that has good thermal storage. The downside is getting them cool again. So, it's a trade-off. There are issues that relate to thermal conductivity, thermal inertia, and other issues.

If you keep dumping more and more energy, and can't get rid of it, you are going to have a problem. An analogy: If you had a new computer or device that only had to be operated for 2-minutes on, and you could leave it off for 20 minutes, you could just grab a giant chunk of copper (or aluminum) for a heat sink and allow the thermal mass to "soak-up" the heat during the 2-minutes of operation. You'd have plenty of time to let the heat leave via various means -- conduction, convection, radiation.

OTOH, if you have a car that needs to dump huge amounts of heat repeatedly, as in F1 cars, you will find that the carbon will cool-up quickly and cool-down quickly -- and has relatively low thermal bulk mass. There is a huge amount of air flow that can cool it down, and it doesn't lose structural integrity when it is glowing red hot. They just change out the ducting, and use the ram air flow to remove the heat. Having a higher thermal mass would not necessarily be a good thing.


The whole area of thermal conductivity, thermal resistivity, and venting can get somewhat involved.

And, if you are looking for additional air-to-metal area for heat exchange, you will get some benefit from the internal fins (see the picture of the steel rotors in the previous posting), and can get more area from the x-drilling. The other benefit is lowered rotational inertia. If you are trying to get that nTH degree of performance, and find that the bulk of the cooling is being accomplished WITHOUT regard to thermal mass, then it might be important to shave off some weight, especially at the outside of a rotating object! More weight means more kinetic energy to dissipate during a stop. So, it can get involved.

IF YOU removed the internal fins, you would have more thermal mass – hey?

As I mentioned, Brembo & Porsche still x-drill rotors.

1killercls

nice work ERIC.

azian21485

first i would like to point out that neither f1 nor any professional road racing teams use drilled rotors...no porshe's racing teams don't use drilled rotors either...i would think that looking at what professional drivers use on their race prepped cars is more important than a factory car eh?

why does porsche use drilled rotors on their production cars? my belief is because their main purpose is to sell cars...advertisement...if a rich person is in their midlife crisis and wants to buy a porshe, he'll think that having crossdrilled rotors will slow him down faster and add to the "i have a porsche, i'm rich, and i have cross drilled blinging rotors affect"

same thing applies to brembo here

yes porsche isn't stupid, that's why their teams don't use cross drilled in their race prepped vehicles

drilled rotors as everyone knows wasn't designed to cool the rotor as we all know..that is not their purpose...they were not designed to help stop shorter distances (which is THE main purpose of having brakes in the first place)...they were only designed to expel gases that don't exist anymore

lets look at the main purpose of having brakes...we all know that friction is what causes the car to stop, more surface area provides the pads a place to "grab" which causes more friction which allows the car to stop faster...drilled rotors take away from the surface therefor producing less friction = less braking power...why get drilled rotors?

but i see that your main concern about drilled rotors is that they are able to cool down faster due to the increased surface area (more air touching the rotor allow heat to dissapate)...but this is also another downside to drilled rotors in regards to structural fragility...taking away mass from various parts of the rotor will make the rotor weaker...secondly, the drilled rotors will heat up faster and cool down faster and repetive quickly heat and cool with a weak rotor will cause the rotor to break...warped rotors will stop the car cracked ones won't..another reason why racing teams don't use drilled rotors

you are right about lower inirtia but i'd rather have a car that can accelerate just a LITTLE bit slower with large blank rotors than a drilled rotor but be able to stop MUCH better and safer than a drilled rotor i'd take the blank rotors and so did racing teams

slotted rotors are mainly used to keep dirt and debri away from the braking system..thats why they are found on rally cars...yes there's no drilled/slotted rotors on rally cars either..only slotted

so the MAIN purpose of having brakes is to safely stop your car...drilled rotors don't accomplish this over blank rotors in neither stopping power or in safety...this is why so many proffessionals (no i'm not a professional) still continue to say that drilled rotors are unnessasary

EricL

Porsche racing teams use and have used rotors with holes in them. When you say "no porshe's racing teams don't use drilled rotors either" (sic), you're basically saying that you know that every Porsche team on the planet doesn't use them. Porsche ceramic rotors have holes in them. They have also used the new ceramic rotors in racing apps. HOW you make the hole will influence cracking. If the hole is produced (as are the vents) as a result of the casting or foundry process, there is no reason that they will automatically result in a crack. And, yes, as shown above, the carbon rotors are already very light and don't have "x-drilled" holes.

We have different opinions on this. And, you now need to find everyone on the planet that call themselves a "professional driver" and get ongoing updates about their brake usage.


I've seen the argument about style and function in regards to brakes -- and I could argue one way or another about this issue. Variety is what makes racing interesting. Some people manage to defy convention and orthodoxy to win.


Well, that's your opinion. I guess form wins over function -- or doesn't make enough of a difference to really matter.

Interesting that Porsche spends a lot of time reducing weight and optimizing designs for their cars, and still needed to induce buyers to its new Carrera by providing cross-drilled ceramic rotors. (I guess the owners should know they are going to die from the cracks they will get; you did make a statement -- further down -- about how a cracked rotor won't stop a car, but a warped one will. )

So, when I look at the price of those rotors, and the applications they are used on, and consider that you don't know HOW the hole is formed *and* this is never discussed in much depth, I'll just suggest that there are many variables to consider. IMO, if "holes" were so bad, Porsche should be “trashed” by automotive tech professionals and criticized for building an unsafe car for "the rich-midlife-crises crowd. I'm sorry, but I'm not ready to make that jump *and* believe that Porsche sells to a bunch of light-weight wanna-be racers.

And, I'll have to continue to wonder about this as well. Perhaps there is a giant conspiracy to get buyers to replace their cracked rotors over and over again. But, then, wouldn't people say, "hey, I've got burned by those shit holes over at Brembo ... why don't they stop making those holes that cause such poor performance?" I guess I should assume -- form always trumps function, and that engineers are incapable of getting a hole in a chunk of metal that wont crack under repeated thermal stress. Yep, it's conclusive "holes bad!"


Here's a comment from Rennsport Systems' website (yea, they don't know shit about building race stuff).

"Porsche used cross-drilled rotors with mixed success. The Zimmerman rotors used on the 930 Turbo brakes were very soft and crack prone, even though the holes were chamfered. The later Brembo rotors will also show some wear when used with most performance brake pads. Some of the best rotors in the world are made in Britain by AP and Alcon. Those rotors, when properly adapted, seem to be superior to the Brembo ones in terms of wear and crack resistance. All drilled rotors will crack sooner or later if overheated. Slotted rotors are more durable in this regard however they are heavier. One reason that most large iron rotors are cross-drilled is to save some unsprung weight. Since nice big, light, carbon rotors cost $1000 each, saving some weight without bankruptcy, is important. Plus, carbon rotors possess very little friction until they reach 500-600 degrees F. Porsche's PCCB ceramic matrix rotors while very light, seem to have mixed success when used for track events.

"Mixed success when used for track events" (They didn't say "no success" and even Ferrari F1 has mixed success in racing. And, they are talking about drilled rotors. There is very little effort and thought used in regards to HOW the holes are put there. And there is very little effort and thought used to see how they work with certain materials. You can have big cracks, little ones, or no cracks -- it depends on a lot of factors.

So, I guess you know for a fact that the rotors with the internal fins and slots will a) never be used successfully in racing and b) will never ever work due to the holes in them. Do you really know that much about materials properties, racing, racing simulators, CAD/CAM/CAE, and simulation to already determine the outcome of those x-drilled and finned steel rotors?

People try a lot of stuff to win. And comprise and trade-offs seem to part of most leading-edged endeavors, if someone wins by dropping a bit of inertia and has some cracking, do you think they will take away the trophy? A win is a win – however you accomplish it.

You try and make the issue black and white, but it is "grey." I've seen this argument show up again and gain. If you decide -- as a team owner or vehicle owner -- that you have a greater possibilty of wining by drilling some holes to a) increase venting and/or b) reduce unsprung mass and rotational inertai, who can claim they are stupid or wrong if they win a race?


"Everyone?" Do you really know everyone? And you also knows what "everyone" thinks and does?

Hmmm... One of the reasons I would consider holes in the rotors is for additional venting and for reduced inertia.

Well, if friction was the only issue, everyone would just put on sandpaper on sandpaper. You get a lot of friction from that. It's just not the simple.

Back to black and white thinking again. And, you've just made an argument for never slotting your brakes. Once again, it's just not black-and-white. And, if you happen to choose a pad that has a lower coefficient of friction, do you think that the car will not stop as well? (You should think about this for a while).


How do you know this?

Once again, you take away mass by using lighter composite materials. You lose mass when you slot them. So, by your argument, don't go with less thermal mass, and blow off the carbon brakes, or anything that experiences lower delta-T. There are a number of things to consider and people make a number of different designs using different material and designs. Let the buyer or racer decide what's right for them. I sure don't know what "EVERYONE" wants.

And you assume that cracked means catastrophic failure == your argument about the car not stopping. The holes generally show stress cracks long before they fall apart. I've had cracks in non-drilled and drilled rotors, and had plenty of time to figure out that they needed to be replaced. If they were really that dangerous (meaning zero braking), they would be outlawed by DOT and most racing bodies. I've yet to hear about that. We've had members with cracked Brembos and they weren't contacting us through John Edwards!

And, I'm so bewildered by your logic process about how they must heat up and cool down faster and this equates to rotor break up. Do you know for a fact that the material MUST crack due to thermal swings? (How high? What material? ...)

Carbon pads and rotors heat up and down at a terrific rate; the carbon has a very low heat capacity relative to the iron and heat up and down much faster. And, they are NOT known for cracking. They are a different material. And, it's quite possible that one material will fail without any holes and/or slots, and another will work reliably for years.

And, then you assert that ALL racing teams DO NOT USE rotors with holes in them. Please check again. And, if you want to assert that a particular team or body doesn't use them, fine. I have no problem with that. When you say "racing teams," your including every racing team in the known universe. IMO, that is basically unprovable.

Whatever you want to choose for your car is fine by me. I'm sure everyone will be glad that you are so much safer than the other folks running slotted and/or x-drilled rotors. I'm sure they will be interested to know their perceptions and choices are definitly faulty

Wow, you should apply for the job of "GOD" since you’re "all knowing." It must have taken quite a while to call every racing team and take a poll of all of the "professionals" on the planet (oh, and all of the rally teams too!) -- hey?

I'm also glad that you've decided that drilled rotors don't add safety to a car. I feel safer now and I'm sure all of the known universe will happily remove their slotted, drilled-and-slotted, and drilled rotors now that you've commented about how unsafe they are. Wait -- I'm going to call all my friends right now. I need to make sure that they don’t enjoy them anymore and tell them that the improvement they believe they got is just an illusion.

azian21485

yes companies use different materials to form their brakes..there's alot of factors when seeing which brakes are better..but to be able to compare how a drilled rotor goes against a blank rotor you have to have a control somewhere..so the control is if you had the two types of rotors, same width, diameter, material, everything but have one drilled and one slotted which one would be able to stop better?

you're asking to compare carbon brakes with some other material...this is no longer comparing a drilled rotor to a blank rotor anymore...it's comparing two entirely different brakes

the above applies to brake pads..they have nothing to do with our argument..so if we compared both rotors and used shitty pads on both rotors what would be the outcome? some shitty braking

also, when i referred to the slotted rotors being weaker by taking away mass, once again you brought up carbon brakes...we cannot consider the type of material in this argument right now because this is basically comparing drilled to blank. what is weaker, a piece of paper with holes through it or a simple blank sheet of paper? by drilling holes in the rotor you are making it weaker...not by using a lighter material will you make the rotor weaker but by drilling away at it you will

also, in no way did i say the drilled rotors WILL crack..there is just a much higher probability that they will..read above

azian21485

also to note, quickly heating and cooling will have more chances (notice i've never said it WILL) to cause warping or cracking to the rotor than slowly heating and slowly cooling

for example, try driving your car hard around and then immediately spraying it with water..then do it repetatively what do you think will happen when the rotor is constantly expanding and condensing rapidly...again the type of material isn't a concern because it's a "constant" or the same for both types of rotors

TypeS_boi

rep points for both you bishes just for giving me something good to read while in class. Nice work EricL

Bobbydoedoe

lol i'm also reading this thing in class

EricL

So, if you remove the vents in the rotor, you now have more mass, and more thermal inertial. You've removed less metal -- right? There is more mass -- right? However, people have been trained to say "vents good."

I'm back at the original comments about "intended use." What you would select to slow down a 1-million-ton hauler that only goes 1 MPH and only make one stop in a 24-hour period?

If you take a blank, and then x-drill it, it might be more stress prone than the one without it. For example, there are folks here that have had x-drilled rotors that were terrible.

Once you compare one maker's iron against another’s, you could do a series of comparison tests. Someone would be responsible for determining HOW the rotors were tested (repeated 80..0 stops, staggered 60..0, 80..00, varied cool down periods, etc.). IMO, it is important to speak about "trends" and generalities and realize that some people have enlisted the help of some very talented individuals and universities to test and model their designs. So, conventional wisdom can let you down. IMO, who's doing the work is very important.

RE: testing different brake combos: I believe that the type of testing could have a large impact on how it turned out.

I've had an OEM solid rotor crack and a slotted/x-drilled last so long, that I replaced it when I just couldn't grind it (lathe it) anymore. That's just one experience, so I want to make that very clear.

<------------>

And, now there is the issue of more mass is better *or* to read your comment another way (with regard to your paper analogy), anything with voids, or other process that makes the surface or bulk of the material non-homogenous (or reduce overall bulk), is going to reduce strength and increase delta-T. Certain types of "holes" in paper -- or other material -- can result in increased tensile strength in one axis. Let's leave the paper alone for now -- OK? Feel free to disagree. This would take a while to explain, and has very little to do with our cars. Sometimes common sense eludes us, and I personally believe that uncommon and innovative thinking relies on defying conventional thought.



Let's assume that you're correct and removing mass is always a good thing. IOW, you contend that increasing the thermal inertia is good and removing mass from x-drilling (AKA holes) is bad. You say that the material will undergo a lower change in temperature if left alone (no x-drilling/holes).

So, if this is taken literally, makers SHOULD NOT put internal venting inside their rotors. Putting the fins inside the rotors (vanes) reduces the strength of the rotor by your argument and removed thermal mass. IN a sense, part of this is true and under certain conditions is completely true. (So, why would anyone want to put vents in a rotor?)

So, if you now have a solid rotor, its temperature will rise more slowly (overall) due to the increased thermal mass. More of the same metal will take more energy to heat it up to a given temperature; this presumes that the conditions are controlled.

The vents inside of the rotor will result in LESS thermal mass. If the rotor was used in a vacuum, the vents would basically be useless (there are some second-order radiative issues, but let’s leave them alone. However, we live in an atmosphere, and the internal vanes not only work as an air pump, but increase the air-to-metal transfer area. So, if a too-simple analogy is applied, someone could arrive at the wrong conclusion. In the case of the cross-drilled holes, there are two main issues. How are the holes put in the rotor? Is it part of the casting/foundry process or is it drilled later? If we can agree that the fins are put in by a casting process, and can agree that some technologies would allow for holes (AKA cross-drilling) to be put in via the casting/foundry process, the thermal issue would be: thermal bulk is reduced, but some cooling is gained. Depending on the vane structure, center cooling aperture, and other issues, who can be sure that the holes -- as used in the Porsche ceramic rotor -- don't increase airflow, heat exchange, and even turbulence that can be used to reduce any stagnant, boundary-layer?

If you study the paragraph above, there are two competing processes that:

1. In one case reduce thermal mass.
2. and in the other case, increase air-to-metal contact area. (And items like: turbulence, boundary layer, increased air flow, and synergistic effect from "holes" and other non-obvious convective and conductive issues.)


So, if you add enough venting, you don't necessarily end up increasing the temperature change; this is predicated on thermal resistivity of the material *and* on how much air is going to pass over the surface of any removed metal.

If the metal that is removed allows the rotor to dump (transfer) more heat via conductive/convective heat transfer -- from increased air-to-metal surface area -- when compared to the SOLID rotor with its poorer heat transfer that results from its smaller air-to-metal surface area, the rotor will experience a lower temperature rise for a given stop.

IOW, what's the difference when removing metal, if the metal removed results in better heat transfer?


IMO, you could fill up a bookshelf with all of the "stuff" that would impact design and engineering decisions regarding all of this.

-- These are my opinions from my experience. Feel free to disagree --

EricL

Yes, that seems reasonable enough. This is the definition of thermal shock. Some related topics: annealing, and hardening.

Take a chunk of steel, heat it up, and then let is cool slowly. If it has a bit of carbon in it, you will be able to work it with a steel file or alter it. You generally get it red hot and then let it slowly cool.

If you take the steel you worked on, then heat it up to blue, then "quench it" in some oil or water, you will harden it; the crystal structure changes.

Annealing:

“A heating and cooling operation implying usually a relatively slow cooling. Annealing is a comprehensive term. The process of such a heat treatment may be used: to remove stresses; to induce softness; to alter ductility, toughness, electrical, magnetic, and/or other physical properties; to refine the crystalline structure; to remove gases or impurities; to produce a desired grain/structure. In annealing, the temperature of the operation and the rate of cooling depend upon the material being heat treated and the purpose of the treatment.”



Thermal shock:

http://www.bellgossett.com/Press/thermalshock.htm

There are also problems with thermal shock in semiconductor devices -- among other things.

joebennz

pos rep points for both drilled and blank rotors

VeeralS05

ok so you suggest we get brembo rotors right? and ceramic pads?

Rod

Haven't you been listening to anything they've said?!

fuzzy02CLS

iTrader: (2)

Everything I have read on brakes(ALOT) says the only way to decrease stoping distances is to increase the rotor size. So you have more surface braking area. Things like X-drilled & slotted add to looks more so, but also help keep the rotor cooler. Cooler brakes don't translate into shorting stopping distances, but they do allow for increased brake feel & restaince to brake fade after repeated braking. From what I have read.
I also have read that drilled rotors are prone to cracking at high temps. I had 3 sets of them on different cars & haven't had this issue & don't know anyone who has, so I'm nut sure if this is true. Although maybe if you ran on a track & braked from 150+ several times?
I saw a NASCAR race a few months ago. They had camara's on the brakes of some of the cars(something about new brake rules) Those things got so hot they glowed orange/red when they were used!

azian21485

in alot of race cars the brakes will glow hot...imagine hitting the brakes at 200mph

also, yes increasing the diameter of the rotor will help reduce braking distance as long as you upgrade calipers and pads...there's no use having the extra surface area if you're not going to have something grab it..but that's not part of the discussion (remember we are only comparing drilled and blank rotors)..back to the topic though =)


before i talk about vented rotors, i assumed that in our disscusion that both the blanks and drilled rotors were vented (who doesn't use vented brakes today?)..remember we have to keep all the variables that applies to brakes the same when comparing just drilled and slotted...a vented rotor will be weaker than a completely solid rotor...but if you add drilled holes to the vented rotors they will be even weaker

back to the structure stability thing...yes adding vents will also cause the rotor to be weaker (we are still taking away mass) however we must find a way to keep the rotor cool somehow to prevent the pads from fading.....drilling the rotors are taking out even more mass from the entire rotor which will cause it's structure to weaken...vented rotors will still be a little weaker than entire solid rotors(but solid rotors are gonna get hot and stay hot and we don't want that)

EricL

Increasing the diameter of the front rotor will NOT always decrease brake distance.

If you have ABS, and you’re on a wet or dry surface, you will find that the stickier tires will have the greatest influence on overall braking distance. If your ABS is working, your brakes are big enough. If they weren't, you wouldn't be able to get the ABS to engage (pulse).

There have been many tests that have shown that larger rotors did not equal shorter stopping distances. At least not during one or two medium speed stops.

And, depending on who's making the brake kits, you may very well find that the front-to-rear balance has been negatively impacted.

IMO, get bigger disks from a reputable vendor *and* realize that the main advantage is reduced fade and better feel at the limit.


Here is a link to a Wilwood brake kit. IMO, these are nice brakes:

http://www.acura-cl.com/forums/showt...=125033&page=1

Pics of some nice kits here: http://www.brakezone.com/html/big_brake_kits.htm

azian21485

yea i agree wilwood are very nice brakes =)

and tires have ALOT of influence how braking distance...wow we agree on sumtin yay

Chopsie

Everything I ever wanted to know about Rotors thread
guys

VeeralS05

so in english what should i get? i'm thinking of brembo rotors and some AEM brake pads..

rezurex

no no, it means we should get DRUM brakes guys

fuzzy02CLS

iTrader: (2)

Depends on the car used to test those brakes. If it's a car that already has a great brake setup, of course it's not going to make much of a difference. If your going from little ass 10" rotors on a neon to 13" or 14" you damn well better see a braking difference.

Tires are important to braking. Sometimes a change in tires alone will shorten your stopping distances.

SpeedyV6

For street use I'd just keep buying Brembo blanks. Replace or "turn" your rotors when they warp. This will save you a lot of $$ over a big brake system and roughly equal the performance.

EricL

Yes, it depends on lots of things. I've seen a number of tests where the change in brake rotor made very little difference when stopping was performed from lower speeds and ABS was engaged. Once you add "some sticky new shoes" and some repeated high speed stops, you’re really going to benefit from some nice oversized rotors. The VSA also uses up the brakes during cornering; the VSA can shut off if it detects the brake temps getting too high. (No sense boiling the brake fluid. VSA doesn't work too well with air in the brake lines!)

If you put down stickier rubber, you are generally going to stop quicker; same thing applies to lighter wheels. If you already have really sticky rubber and just trade for another brand, you could end up stopping shorter on one surface at the expense of another.

When you replace the stock Michelin MXM4s with max-performance rubber, don't be surprised to see a large decrease in braking distance on a number of different road surfaces.

VeeralS05

my toyo's made a hude difference