Pic of winter set on 245 40 19 OR 255 35 19

[KrisHansen]

Anyone has a pic of their Audi on 245 40 19 or 255 35 19 on any brand?? Thanks

[ChipB]

Anyone has a pic of their Audi on 245 40 19 or 255 35 19 on any brand?? Thanks

Here's my car with OEM wheels (255/35R19), no spacers. This was taken before I installed the Ohlins/SL coilovers, so it's the stock ride height. Since 255/35R19 is standard OEM for the S5, you can also take a look at any pic on the Audi web site.

[mxrz]

Anyone has a pic of their Audi on 245 40 19 or 255 35 19 on any brand?? Thanks

245/40-19 is too large (2.6% bigger in diameter)... 225/40-19 is closer to stock size, obviously this narrow size is only good for winter.

[mr shickadance]

too large for what? stock? yeah i guess, but if you are running it on all 4 corners, there is nothing that will be wrong except that your speedometer will be off by a percentage i am too lazy to calculate


the rolling diameter is only a concern if you run staggered set ups, if you are running the same tire on all 4 corners, to a certain extent, it really doesn;t matter, (obviously you cannot extrapolate this idea to monster truck tires) but running a slightly larger or smaller rolling diameter than stock rolling dimater the only negative will be that your speedometer will be not so accurate

[mxrz]

too large for what? stock? yeah i guess, but if you are running it on all 4 corners, there is nothing that will be wrong except that your speedometer will be off by a percentage i am too lazy to calculate


the rolling diameter is only a concern if you run staggered set ups, if you are running the same tire on all 4 corners, to a certain extent, it really doesn;t matter, (obviously you cannot extrapolate this idea to monster truck tires) but running a slightly larger or smaller rolling diameter than stock rolling dimater the only negative will be that your speedometer will be not so accurate

You do know how ABS works right? That's why it is recommended to stay as close to stock diameter as possible. ABS is an integral part of TC/ESP, so pretty much all electronic drivetrain systems will be affected.

[mr shickadance]

if op was driving at 60 mph with the stock 255/35/19 tires vs the 245/40/19 that he suggested, his speedo would be off by 2.55 mph reading at 58.45.....not even close to enough to affect ABS by a long shot


of course is op was traveling faster then 60 then his actual speed would be progressively slower, but nothing to a point where it would seriously affect ABS until you hit numbers reaching greater then 150....at that point we can both agree thats some pretty reckless driving and even the greatest most accurate ABS is not going to do much to save your life at that point

[ChipB]

You do know how ABS works right? That's why it is recommended to stay as close to stock diameter as possible.

Please explain how a 2.6% difference from stock would make a difference. I agree with MrS on this one - ABS is not affected unless the diameters of the tires are different from each other. Having said that, I too would recommend staying as close to stock diameter as possible for several reasons - the speedo error is one, another is that you effectively change the gear ratio which can affect mileage and performance, the odometer will read low, and your on board computer's calculation of MPG will be off.

[mxrz]

2.6% in diameter difference is substantial, please call TireRack, they will set you straight on why this is not a good idea, maybe you will believe them.

[Beast]

ill post mine up when i get home

[mxrz]

Please explain how a 2.6% difference from stock would make a difference.

ABS uses wheel rotation to determine speed, a critical part of its function. Fooling it by changing the tire diameter will make it kick in too soon, I'm not sure about you, but I don't want ABS to engage even a millisecond too soon, it's good at unsettling the car when you're driving fast around a corner for example.

[GuzmanA5]

i think OP is referring to Winter set in 255 35 19

[crisp74]

ABS uses wheel rotation to determine speed, a critical part of its function. Fooling it by changing the tire diameter will make it kick in too soon, I'm not sure about you, but I don't want ABS to engage even a millisecond too soon, it's good at unsettling the car when you're driving fast around a corner for example.

i have a basic understanding of the mechanics of abs, but that's such a minimal difference in rotational diameter i can't see how it would cause it to kick in so much earlier. the example you provided is bad to begin with. giving up the throttle mid-corner while going fast is a great way to unsettle a car. braking hard mid-corner, whether or not it's activating abs, is an even better way to unsettle it.

[ChipB]

ABS uses wheel rotation to determine speed, a critical part of its function. Fooling it by changing the tire diameter will make it kick in too soon, I'm not sure about you, but I don't want ABS to engage even a millisecond too soon, it's good at unsettling the car when you're driving fast around a corner for example.

You have an incorrect understanding of how ABS works. The rotation speed of a wheel is not important to ABS at all - what's important is any abnormal deceleration of the speeed of rotation of a wheel - which is indicative of a wheel that is locking up (skidding). ABS is also used to look for differences between rotation speeds of the different corners, which the system figures must be due to either slippage or low tire pressure (this is how indirecet TPMS works). The absolute speed of the car as it goes down the road is immaterial. Your ABS doesn't kick in any quicker if it thinks you're going 60 MPH versus 58 MPH. Consequently if all 4 wheels are 2.6% larger diameter than stock ABS operation is not affected at all.

I would not be surprised that Tire Rack suggests sticking as close as possible to stock - for the reasons I cited previously.

[GuzmanA5]

Pics of winter set 255 35 19 turning into ABS got to love this site!

[mxrz]

You have an incorrect understanding of how ABS works. The rotation speed of a wheel is not important to ABS at all

That's just plain wrong, the rotation of the wheel is the first sensor in the electrical diagram of any modern ABS system.

[mr shickadance]

op, i dont have any pictures on hand of what it would look like, but if you went to tyre-stretch.com or something like that, its basically a website that has pictures of what certain tires look like on certan wheels

i can;t garuntee the pic will be of an a5/s5, but it should give you a good enough idea of what it will look like personally i still think 19 inch is too much rim and may end up bending it, but thats your decision


in terms of tire, the narrower 245/40/19 is better bet for winter, its a narrower tire, with a taller sidewall, it will give you more protection than the 255

currently i am running a 245/40/18 winter tire on my NUEs, but my car is at the shop getting brakes done, the tire fits the car very well, i can;t imagine there being much difference between that and a 19 inch wheel

[crisp74]

from last winter, stock wheels with 265/35 blizzak lm25 tires (these are no longer made and were replaced with the lm60's). car is dropped about an inch.

[KrisHansen]

from last winter, stock wheels with 265/35 blizzak lm25 tires (these are no longer made and were replaced with the lm60's). car is dropped about an inch.

You car looks like a disaster

[mr shickadance]

also looks like its the middle of winter?

[ChipB]

.. the rotation of the wheel is the first sensor in the electrical diagram of any modern ABS system.

Of course there's a rotation speed sensor - so ABS can determine if there is a significant difference in rotation speeds between wheels, or abnormal deceleration of wheel rotation.

[mxrz]

Of course there's a rotation speed sensor - so ABS can determine if there is a significant difference in rotation speeds between wheels, or abnormal deceleration of wheel rotation.

HEH, it's a little more complex than that. The speed sensor is used to determine angular velocity of the wheel, IN ADDITION TO calculating linear velocity (vehicle speed) because it requires both. For example, modern ABS systems can control front brakes independently, however, not above certain vehicle speed, to prevent a chance of further loss of control. But more frequently, linear velocity is used in the calculation of slip ratio to determine optimum braking pressure to each wheel. Generally, ABS tries to maintain a 10 to 30% slip ratio, but this 10-30 band moves on the 0-100 scale, based on vehicle speed.

[mr shickadance]

either way, the point still remains, the variance of 3% between stock rolling diamter is not enough to fuck with your ABS to the point where it would cause a significant effect



my understanding of ABS is that there are controllers that monitor vehicle speed, and when the brakes are engaged, these 'controllers' make sure that the deceleration is logical and could exist in real, example, going 60 mph down to 40 mph in say 10 seconds (bc i dont know), and going 60 mph to 0mph in .001 seconds.....so the controller processes this information on a real time basis, and thinks, well.....a more logical thought would be that the car did not come to such a sudden stop, and that the tires are locked up and the vehicle itself is still moving forward


then the pulsing of brakes to make your car handle slightly better during emergency braking conditions



i mean yeah, there is a LOT more that goes into it, but thats the basic idea, and the fact that your are only marginally different then stock rolling diameter means that you would be ok

[mr shickadance]

oh and tire rack will also not sell you two different sized tires if you have an awd system even if you say you know what you are doing, accept all risk, and understand the differences..... sometimes companies just like to cover their ass vs. sell you something.

to add creditibility, i buy all my tires through tire rack.

[KrisHansen]

HEH, it's a little more complex than that. The speed sensor is used to determine angular velocity of the wheel, IN ADDITION TO calculating linear velocity (vehicle speed) because it requires both. For example, modern ABS systems can control front brakes independently, however, not above certain vehicle speed, to prevent a chance of further loss of control. But more frequently, linear velocity is used in the calculation of slip ratio to determine optimum braking pressure to each wheel. Generally, ABS tries to maintain a 10 to 30% slip ratio, but this 10-30 band moves on the 0-100 scale, based on vehicle speed.

I agree on sensor calculating angular velocity

[mxrz]

I agree on sensor calculating angular velocity

That's a direct input, pretty simple, but for vehicle speed, it needs a preset value that should not change and that's the tire diameter. Sure there is a tolerance, but the value moves within this tolerance even with a stock tire, based on the pressure inside the tire, the speed, getting a flat, etc... Same goes for detecting slip between individual wheels, some tolerance is required even before you mess with the size, because we all know that when a car turns, the outside wheels spin faster than the inside wheels. So basically, the tolerance is there for all kinds of conditions that occur with stock size. The tolerance is NOT there so people can go and change tire specs at will, that's why there is no reason not to stick with factory diameter. Sure, your car will not blow up, but why take the chance that under the right (or wrong) circumstances, a modification will prevent a safety device from working correctly. There just isn't a good reason to do that.

[mxrz]

If you want a 40 series side wall, get a 225mm wide tire, why go for 245 when it serves no positive purpose in winter...

[mr shickadance]

....so let me get this strait, according to what you said, the tolerance is there for things like a flat tire, and fluctuations in air pressure......but not there for a difference in stock rolling diamter?


so the car knows and can respond properly to a sudden blow out (which is a difference between rolling diameter) but a different tire (which is a difference between rolling diamter) makes it go haywire? im sorry but i don't follow?


i mean i see your logic in "dont abuse the tolerance given" but its not a finite thing, its there no matter what.....so the harm really is in nothing if the technology is already there to cope for it

[mr shickadance]

also, a 215/40 has an 86 mm sidewall, and a 255/35 has an 89.25 sidewall

the advantage between a 245/40 is the fact that you have a larger sidewall on a 19 inch wheel.....idk about your location, but in the winter when the snow comes down, the roads get even shittier, and you are less likely to bend a rim with a tire that has a larger sidewall

[mxrz]

....so let me get this strait, according to what you said, the tolerance is there for things like a flat tire, and fluctuations in air pressure......but not there for a difference in stock rolling diamter?
so the car knows and can respond properly to a sudden blow out (which is a difference between rolling diameter) but a different tire (which is a difference between rolling diamter) makes it go haywire? im sorry but i don't follow?
i mean i see your logic in "dont abuse the tolerance given" but its not a finite thing, its there no matter what.....so the harm really is in nothing if the technology is already there to cope for it

You didn't get it straight. The car knows nothing, it is expecting the tire to be stock diameter. Since a tolerance is needed even with a stock tire, it stands to reason that if you already take up some of the tolerance with a higher diameter tire, you leave less room for conditions that tolerance was designed for in the first place, it's a simple compounding effect. Why take the risk, there is no benefit in doing so.

also, a 215/40 has an 86 mm sidewall, and a 255/35 has an 89.25 sidewall the advantage between a 245/40 is the fact that you have a larger sidewall on a 19 inch wheel.....idk about your location, but in the winter when the snow comes down, the roads get even shittier, and you are less likely to bend a rim with a tire that has a larger sidewall

That's great but I was talking about a 225/40-19 tire which has the same sidewall height as the stock tire and a narrower section width which is what you want for winter. Of course 245/40-19 has an even taller sidewall, but it's very close to the 3% difference threshold... Go ahead, load up the 1010tires.com tire size calculator, and put in something that's over 3%, and see what it tells you. It doesn't tell you your speedo will read wrong, that's not a critical problem, it will tell you that you risk brake failure. If you inquire with 1010tires as to why, they will tell you about ABS, just like I did.

[mr shickadance]

ok but we still talking about a car that has <3% difference between stock rolling diamter


and again, the concept of running a thicker sidewall is to improve the chance of NOT bending a rim, ok so i got the number wrongs, but the line of thinking is still spot on, a 255/35 sidewall is still a sidewall that is very much a risk to bubbling (brand new tire) or burtsting (brand new tire) or bending the wheel (brand new wheel)



so with a higher sidewall then OEM, you will agree that the rolling diamter (lets just call it RD cuz im lazy) will not get larger, only smaller, as the tire can only deflate, i mean yea merginally you super over inflate it it will get bigger but lets ignore that highly unlikely situation.

the AM (After Marke) RD is higher then OEM RD savvy? the tire blows, the AM current RD, only getting smaller will only stand to stay within tolerance, as under deflation (abelit this happening super fast) the AM RD will approach the OEM RD and then pass it as the RD gets lower ....still staying within the tolerances



and the benefit? again, having a thicker sidewall is a godsend when you hit the enevitable potholes that are created during winter driving



i dont think i will ever change your mind on this, but i can assure you, running the tire that OP is considering will be totally fine, aside from the slight inaccuracy of his speedometer (at 58 mph, his speedo will read 60)

[KrisHansen]

If you want a 40 series side wall, get a 225mm wide tire, why go for 245 when it serves no positive purpose in winter...

I want to keep my 19" rims all year long.. but I cant find much on 255 35 19 so I've been advised to get 245 40 19

[mxrz]

Forget about inflation, even before you begin there are already two factors that can make the tire bigger:

1. Manufacturing tolerances. You may get a tire that is already, from the factory 1% larger.
2. Speed. At elevated highway speeds, the tire diameter gets measurably taller in the center.

Each argument alone can be dismissed, but it all adds up, that's what I'm saying.

[mxrz]

I want to keep my 19" rims all year long.. but I cant find much on 255 35 19 so I've been advised to get 245 40 19

That's fine, and I suggested 225/40-19, which is available in winter threads, I'm running that right now because I also wanted to keep 19" wheels... It's the only 40 series 19" tire that matches stock size. Did you tell whoever made that suggestion that your wheel is only 8.5" wide? Normally, 255 wide tires go on wider wheels, Audi is at the narrow limit. That person might have assumed that your wheel is something like 9 or 9.5 inches wide, so that's why he didn't suggest a narrower size like 235 or 225.

[Beakerz]

Here's my winter set-up. The Audi will stay in the garage and out of the snow & salt.

[Wah]

Shit, I miss my black 4runner sport edition with the littke hood scoop. I had some winter tires on them...it was unstoppable in the snowy mountains of CO

[GuzmanA5]

Shit, I miss my black 4runner sport edition with the littke hood scoop. I had some winter tires on them...it was unstoppable in the snowy mountains of CO

CO?? I thought you were in Lebanon

Did you get your car fixed??

[Beakerz]

Shit, I miss my black 4runner sport edition with the littke hood scoop. I had some winter tires on them...it was unstoppable in the snowy mountains of CO

Yeah, gotta love the hood scoop, even though it's fake. Mine is a Sport Edition too, so I got it too. BTW, I run Discoverer ATR all year 'round and they are actually really good in the snow. Maybe not as good as dedicated snow tires, but definitely good enough that I don't even have a second set of wheels/tires.

[ChipB]

I think either these: 255/25R19 http://www.tirerack.com/tires/tires....5&autoModClar=

Or these 225/40R19: http://www.tirerack.com/tires/tires....omCompare1=yes

would serve you quite well.

[KrisHansen]

I just witnessed an Ibis White A5 2.0T mounting 225's on of those winter-setup wheels available at tirerack and it looked like a cripple A5 to me.

[KrisHansen]

I think either these: 255/25R19 http://www.tirerack.com/tires/tires....5&autoModClar=

Or these 225/40R19: http://www.tirerack.com/tires/tires....omCompare1=yes

would serve you quite well.

I just ordered a set of 4 Blizzak's 255 35 R 19.. Wheel guy couldn't comprehend and kept suggesting going smaller.. blabl bla bla... I had to almost tell him to shut the F up about it... thanks for the input! :)