Truck tyre wear 1

[gunyu]

Hello Experts!

I'm looking for conection between the tyre traction (contact surface) and tyre wear in function of tyre deflection and tyre inflation pressure of truck (truck tractors).
I've seen some tyre specification of a manufacturer, where they give radial deflection versus radial force for a given tyre. Based on these curves (nearly lines at 1-2bar), I can measure the deflection of tyre at a given load and infaltion pressure (for a given rim width), so theoreticaly to get the proper deflation is not an issue. Also, as I've seen, they give the "proper" inflation pressure for given load at given speed, and this "proper" inflation pressure determined by also the deflation, which deflation have to be the same at a given speed.
So theoretically, if I would get the best performance and lifetime of my tyre, I should always dinamicaly change the tire pressure, based on actual speed, and load.
I also have seen some figure about the result of lifetime of overinfalted and underinflated tyres.
So what would be the function here?

 

[gunyu]

Hi again,
I forgot to mention, I've found, that Schallamach calculated only with "wheel stiffness" in tyre wear topic, and according to Kraghelsky and Nepomnyashchi complex formula the tyre wear rate is an exponential function of the length of contact area, but these formulas maybe outdated, and also I think they didn't even consider the wide super singles...
so if I use an overinflated tyre, its lifetime will be decreased due to contact surface shrinking (among others), but can somebody please give me a function for rough estimation?...

Thank you in advance!

 

[CapriRacer]

My expertise is in Passenger Car and Light Truck tires, but I suspect that Medium Truck tires (the ones commonly used on Over-The-Road trucks) would react very similarly to those. Keep that in mind as I respond.

The relationship between tire traction and tire wear is highly complex - and reading into your post, it appears that you want to be able to calculate an optimum pressure. So a couple of thoughts:

THEE most important thing about inflation pressure is load carrying capacity. That's the thing that should be driving your quest for the proper inflation pressure.

Secondly, the pressure distribution in a tire's footprint is a function of inflation pressure, but it is also a function of other things beyond the control of the end user. Things like belt angle can affect the pressure distribution - and this is obviously within the control of the tire manufacturer - and while it might make sense for a tire manufacturer to try to match the footprint to the load/inflation combination in common usage, the real goal would be to get a footprint shape that doesn't change much with load or inflation pressure. Obviously some tires will be better at this than others.

What I am trying to say is that you will not be able to find a formula because there are too many overwhelming variables.

But we do know these things:

1) Excessive toe causes rapid wear. It also is a driver for irregular wear.

2) Inflation pressure isn't as strong of a driver of uneven wear as other things.

3) Most tire wear occurs in the cornering mode.

4) While camber does affect evenness of tire wear, its relationship is multiplied by toe misalignment. That is, a lot of camber doesn't cause uneven wear by itself, but a combination of camber and toe will.

5) As a general rule, increasing inflation pressure results in a better wear rate (stiffer tire) even considering the uneven wear it generates.

6) Traction does peak and fall off as pressure is increased, but that exact relationship is subject to the footprint shape. The important thing here is that the curve is fairly flat in the area of normal usage and for practical purposes can be ignored.

7) In Passenger Car and Light Truck tires, the maximum load on the tire shouldn't be more than 85% of the rated load (at the usage pressure)

So I think the answers you are looking for are:

Inflate the tire such that the max load on the tire is 85% of the rated load at the usage pressure.

Pay attention to alignment.

Driving gently is better for tire wear.

And the result will be as good of tire wear with a reasonable amount of traction as you can expect without knowing anything else (such as the vehicle make and model, operating conditions, exact tire make and model, etc.)

 

[gunyu]

Thank you the quick response.
I see some misunderstanding belongs my post...sorry for that...
So I can measure (or calculate) the theoretically optimum pressure in tyres, based on the above mentioned curves, provided by manufacturers. So I can tell you, that for example a 385/65 R22,5 160K marked tyre optimal pressure for normal road condition:
@4000kg load (on a single) @110km/h should be 7,9bar, and its deflection will be 40,5mm...
@1000kg ...................@110km/h ..........1,3bar.............................40,5mm...
@1000kg ....................@20km/h...........0,9bar.............................49mm....

so these are just examples, based on the technical sheet I can measure the proper inflation pressures provided by manufacturer, and I know the deflection, and total contact area as well.
(Just for fun, obviously the truck drivers may can be shocked with that 1,3bar at 110km/h when the truck is empty, but according the manufacturer this should be the proper inflation pressure that case...(for driving or trailer wheels....)

So in this case I would like to concern the regular wear of a tyre of a linear motion, in generally usage, normal road, instead of that complex things like driving style etc....
I feel well, that this wear depend on the contact area, but I don't know and haven't found how...what would be the function.....(for example some measurement concerns the slip angle, but in a linear motion is not a player a think...but maybe yes?..as there is a difrence between the theoretically round/annular circumference, and the deflected one...)

Thank you in advance!

 

[CapriRacer]

And another admission of my limitations: I am a generalist on tires. I know a little about a lot of areas, but I am by no means an expert on tire wear. Yes, I am more knowledgeable than the average guy, but there are folks who specialize in tire wear. Nevertheless, I'll try to convey what I know.

First, I don't know what you may be looking at, but I suspect the curves you have aren't what you think they are. I suspect they are deflection charts based on what is known as a "Load Table". To confirm: Do they say anything about minimums or maximums.

Another way to confirm this is if one of the data points is 9000 kg at 900 kPa (9.0 bar) That is the rating point for a 385/65R22.5 LI=160.

If so, then these would be what is published by a tire standardizing organization such as ETRTO (European Tyre and Rim Technical Organization). That is, they are the maximum load for a given inflation pressure. In other words: They are NOT optimums.

Just a side note: The data you've presented does not make sense except in the context of the load tables. There should not be a difference in pressure between speeds for optimal wear. And one of the reasons I think so is that 1000 kg would make sense as a standard measuring point.

Now let's move onto how a wears when it is rolling at Zero slip angle with no applied torque.

First, let's assume that every portion of the loaded tire is shaped exactly like the freestanding tire is EXCEPT in the area of the contact patch. Please note, this is not true, but it is close and simplifies the thought process as it allows us to confine our examination to the contact area.

Compared to the rest of the tire, the tread in the contact patch has a shortened length (again, this is not true, but it is close) - and for that to happen the belt angle has to change, and that also causes the width of the tread to change. This movement causes wear, especially on the edges of the grooves and button elements of the tread pattern, and not so much in the center of those elements. That's why straight ribbed tires get river wear on the front axle of long haul trucks - most of the wear is taking place near the edge of the grooves.

What that also means is that the tread pattern has a profound affect on otherwise identical tires. That makes studying tire wear difficult. So you won't find a generalized formula.

But slip angle has magnitudes of more significance on wear and that makes a formula almost an impossibility.

What is interesting here is that passenger car tires don't have the wide difference in usage that trucks have and that's why there are different kinds of tires for delivery trucks as opposed to long haul trucks.

 

[gunyu]

Thank you so much again for your answers CapriRacer!
First of all, yes, the data above just examples from the chart...
About the "optimum pressure":
Yes, you have right, maybe I should rethink my previous theory about the optimum pressure. Exactly this is why I'm typing in this forum, and opened this topic...
So I'm pretty sure that in the detailed engineering technical sheet the subjected curves are belong to the specified tyre, and they based on calculation or test results....
The concept is, that a given tyre has deflections in function of load and inflation pressure.
I haven't found these kind of special sheets on internet (which is understendable, more or less confidental details), but I have found similar example curves regarding this topic:

http://www.emeraldinsight.com/content_images/fig/5080060206007.png

So as you can see, these are just curves, they give you the deflection in function of inflation pressure and load, and nothing about speed....(and for given rim width etc...)...
But, the speed modified given pressure and load pairs based also on these curves, so for a given load the manufacturer gives less pressure as speed become lower. Maybe this modification for max. pressure/max load harmonised with ETRTO, but as I've found these are based on other manufacturer's considerations, as the ETRTO (and others, like TRA) is more permissive....
But anyway, "the speed modifies the deflection" rule sounded good for me, and this is what I found in this sheet/chart....
Yes, now I would like to figure out, if they NOT the optimum pressures, then what would they are?
The data suggest me, that for a given speed/load/road combination determines the inflation pressure (via deflection)...which I should call as "optimum" pressure...or souldn't?...
let's say that they are the maximum pressures for given speed/load/road combo...then what will change?...now I try to figure out the rules of the tyre wear, and concerning from that aspect to measure the infaltion pressure for the given maximum sounds good for me...why?...an underinflated tyre case has obvious disadvantages...but what about overinflated tíres?...according the chart, if my truck is empty (1000kg), than I should have only 1,3bar pressure...in this case, my 9bar infalted tyre became overinflated...about 700%....of course, based on the chart....so in this case, my overinflated tyres will show wear as comonly identified as overinflated wear...in the middle of tyre tread...(obviously, this type of wear not typical for general tire life, because the share between the empty and full loaded truck, and the typical underinflation in fleets not considered here...)

Sorry, my mistake, I should earlier emphasize, we are talking about long hauls...and my doubt is regarding the ATIS systems, which, as far as I know don't concern/can't handle this kind of issue (beside their other advantages...)

 

[CapriRacer]

First, thanks for the charts. I'm assuming that those charts are what you were referring to, but what I don't know is where you obtained them - and without additional evidence, I would NOT assume they are the tire in question - and here's why.

Tire load tables are set up by the tire standardizing organizations, based on theoretical studies. A given load table (the relationship between Maximum Load and inflation pressure) is a function of a constant deflection - that is, any combination of load/inflation pressure on the table is a result of the same amount of deflection. Of course, a load table for a different speed would result in a different amount of deflection - BUT - every data point on a given table would be the same.

So it should be no surprise that lower speeds specify more deflection - that's the way the tables are set up.

What those charts seem to be is a comparison of the theoretical values vs actual values. If so, then you should be aware that other brands of tires should show pretty much the same values. That's the whole purpose of the load tables and the standardizing organizations.

(Note: It is also possible that the charts are just actual values with a best fit curve. The charts themselves are a little unclear and I suspect the words were translated into English, which doesn't always result in precise wording.)

Assuming I am correct, then if one would take a bunch of otherwise identical tires, they should fail in lab tests in the same way for any datapoint on the chart.

Second, what you need to avoid is overloading the tire (or conversely, using enough inflation pressure.) Overloaded tires can fail - and sometimes those failures result in serious accidents. You do NOT want that to happen. That's where the load table comes in.

If you know the actual loads on the tires, that is good. If not, then there ought to be some specs on the truck that indicate the designed load carrying capacity of the axles, called GAWR. (Gross Axle Weight Rating) There should be GAWR's for each axle.

If you account for side to side load variation (and actual weights do that, but GAWR's require an up-factor), then I recommend inflating the tire such that the tire is capable of supporting 115% of that load.

Will that be the optimum pressure from a wear perspective? Probably not, but 2 things of importance:

1) Tire wear is much, much more a function of other things, such as alignment, vehicle geometry, and driving conditions, than it is for inflation pressure. So being somewhat off on inflation pressure doesn't result in a huge difference in wear pattern (in spite of what those wear pictures show).

2) It is Soooo much more important that you get the inflation pressure set for safe vehicle operation. Tire wear should be a secondary consideration.

What I am trying to say is that you seem to be OVERLY concerned about tire wear - and I'm not saying tire wear is not important, but that other things is much much more important and inflation pressure is just one of many things that impact tire wear.

 

[gunyu]

Hello, and thank you again.

As I wrote, they are NOT the SAME curves, they only similar/analogue, and they only proves for you, that this kind of curves do exist...

And, yes, they are for only a specified tyre (from one manufacturer identical products, as I wrote:"the subjected curves are belong to the specified tyre"....)...


Anyway, let me quote you:"Tire load tables are set up by the tire standardizing organizations, based on theoretical studies. A given load table (the relationship between Maximum Load and inflation pressure) is a function of a constant deflection - that is, any combination of load/inflation pressure on the table is a result of the same amount of deflection. Of course, a load table for a different speed would result in a different amount of deflection - BUT - every data point on a given table would be the same."

This is exactly what I'm saying, and tried to point out.Furthermore, as I see, the curves are from some measurement or test result (as I already wrote), and the speed indexed load/pressure table corresponds this curves. So based on that, I CAN measure properly the pressure for every load, not only the ones in the table...(but for only the preselected speeds in the table, as I don't know the exact funtion betwwen speed and deflection...)

The second quote from you:
"So it should be no surprise that lower speeds specify more deflection - that's the way the tables are set up."

Ok, so here is my question: Why?...why should the lower speeds specify more deflection?...why that's the way how tables set up?...what is the connection, the function here?

The third quotation:
"What those charts seem to be is a comparison of the theoretical values vs actual values."
Sorry, I didn't catch the point here...

 

[gunyu]

Sorry, for the second quote questions:
I know, that there are ETRTO,JATMA, TRA etc. regulations accordingly, but they gives only speed/max weight rate (as you can increase the load as the speed reduced, and this regulation applies percentages for given speeds...),
but obviously this regulations, and the manufacturer data based on some direct connection/function here, between deflection and speed....

And, yes, the topic here is the tyre wear, which does NOT mean that my intention is to overly concern this topic...but here, in this topic we should discuss that subject, and I would find the connection between the proper inflation pressure concerned the tyre wear.
Thank you in advance!

 

[gunyu]

Ohh gosh...sorry, but there is no post editing possibilities here...so...
Let's say that I have this speed connected load/pressure table (chart), and load/deflection pressure curves (as I do already)....
So If I understend your words correctly, than you say, that in the load/pressure table (chart), the indicated pressure values are not the correct/optimum pressures.
Then what are they?
How should I measure REALLY CORRECT the pressure in tyres, if I would have the chance to adjust the pressures in tyres dinamicly during the trailer load and speed changes on the road? So theoretically, if I could do that, what functions should I follow? My assumption here is a function based on the chart (which based on the curves measured/calculated by manufacturer). And if I follow this rule/chart than I will get the best tyre lifetime/wear.

Here you can see a curve for lifetime/inflation connection (for regular condition...of course for example driving style is not included...)

http://www.michelintransport.com/ple/front/affich.jsp?codeRubrique=37&lang=EN

So there IS a connection between tyre pressure, and tyre wear...

 

[CapriRacer]

OK, so maybe I need to ask very specific questions:

Where did you get the charts?

I know there are 2 sets of charts. Do you have electronic versions of the other charts? Can you post them?

Allow me to quote you:

"....This is exactly what I'm saying, and tried to point out. Furthermore, as I see, the curves are from some measurement or test result (as I already wrote), and the speed indexed load/pressure table corresponds this curves. So based on that, I CAN measure properly the pressure for every load, not only the ones in the table...(but for only the preselected speeds in the table, as I don't know the exact function between speed and deflection...)...."

No, you misunderstand the load tables. They are MAXIMUMS - as in the load listed for a given pressure is the maximum load the tire was designed to carry. If you use the pressures as indicated in the load tables, the tires will be very close to being maxed out for load - and that is NOT the best place to be - and certainly not optimal.

"....Ok, so here is my question: Why?...why should the lower speeds specify more deflection?...why that's the way how tables set up?...what is the connection, the function here?....."

There are a number of things that affect the maximum load carrying capacity of tires and speed is one of them. This is just the way it works. It's the Physics of the situation.

Do you want to know the formula? Would that help you understand? Well the formula for load carrying capacity involves a factor that adjusts the load (and the amount of deflection) based on speed. Normally this is represented by the letter "k" - and is not only a function of speed, but other conditions as well (such as road roughness) - and not normally expressed as a formula. It is expressed as a table.

Sure, you could have this relationship expressed as a formula - and I have actually plotted the values to see how this worked - and it is a decaying log function (or something like that. Math isn't my area of expertise.)

But do you want to understand why speed would affect load carrying capacity? Here's my understanding:

If you think of a tire as a series of segments, then you can imagine that one revolution could be expressed as a line in a graph with the load applied somewhere along that line.

So think of a bridge represented in the same way. If you drive a heavy truck over the bridge it deflects as the truck traverses across. If the truck drives slowly, the bridge deflects slowly. But if the truck drives fast, the bridge deflects fast and that causes MORE deflection as the bridge has to absorb the momentum of the bridge as it deflects.

In much the same way, the structure of a tire has to absorb the deflection and the faster it is applied, the more actual deflection takes place - and therefore, more stress.

"....."What those charts seem to be is a comparison of the theoretical values vs actual values."
Sorry, I didn't catch the point here... "

The point was that these charts seem to be something other than what you think they are. They seem to be just a verification of the theoretical values using a specific tire. Nothing more than that. This would be something that a researcher might do as a step towards a goal - like verifying a computer model.

And a couple of points: ETRTO, JATMA, and TRA are NOT regulatory organizations. They have no force of law. No one can punish anyone for not following the standards published by them.

They are standardizing organizations. Initially, they were set up so tires would ALWAYS fit on rims - as opposed to a given tire only fitting on certain rims - and vice versa.

But they also serve as a resource to help vehicle designers size tires for vehicles - and what is pertinent here - the load tables tell the vehicle manufacturers what the MAXIMUM load a given size tire has, so the designer can size the fenders appropriately.

There are a lot of corollary benefits like being able to know what other size tires may fit the vehicle (if you know the fender's dimensions.)

They do NOT publish "optimal" values of anything. They publish minimums and maximums. And those are voluntarily used by the tire manufacturers. Tire manufacturers do NOT have to follow those standards but they would be foolish not to.

And as I was saying: A tire designer can adjust the shape of the footprint to optimize tire wear - and the shape of the footprint is a function of the inflation pressure - BUT - each tire designer could design their footprints to be optimal at different load/inflation combinations.

What this means is that each tire manufacturer has a different way of doing this, so there is NO universal formula for the optimal pressure for wear. Each tire would be different.

- BUT -

a) Most tire manufacturers will design their tires based on the load tables in some form as this is what the vehicle manufacturers use to size the tires for their vehicles.

b) A radial tire's footprint shape is somewhat insensitive to changes in pressure (Bias tires, less so.)

c) There are other things that have a greater affect on tire wear than inflation pressure does.

And that Michelin graphic: It is pointing out that inflation pressure is important - and they are doing that to get people using their tires to check them more often. It is truly amazing how many people neglect tires, especially the pressure.

But if you'll notice, the 2 graphs are inconsistent. The one on the left shows the wear peaks at some value and the curve is somewhat flat in the vicinity of the optimal value, but drops off more and more rapidly as you get further way.

But compare that to the graph on the right which only shows overloaded values (like an underinflated tire) and the line is somewhat linear, but the rate improves slightly as you go higher - which is the opposite of what the graph on the left says.

I think this means the graphs are not graphs of real data. I think they are idealized graphs based on how tire engineers think tires work )or should work). So be careful.

And as I have been pointing out: There isn't a single formula for wear vs pressure as this is something that can be controlled by the tire designer and each designer will have his own way of doing it. In theory, I could design a tire that has an optimal footprint for wear at 150% inflation (that is 150% of the minimum inflation for the load according to the load table.) That doesn't make sense to do, but it is possible.

To put this in perspective: When I was working for a tire manufacturer, we occasionally collect samples of tires being returned so the wear could be looked at. The idea was to see how well the designers were doing in designing the footprint and using real life returns as a gauge.

 

[gunyu]

Oh..thank you for the answers...
I really don't know, maybe we misundersood each other in a probably important detail...so about the "load charts":
so this is a table, titled as "Load and inflation pressure chart for single fitment use". And in headlines it contains loads (vertically), and speed (horizontally), and in the cells for normal road conditions it contains the pressure values (for each speed/load pair)...and below it contains a deflection and contact area for each speed, and other data accordingly...and this chart is only for this identical tíre products...
And now, thanks for you, I know, that in this table I see the maximum permitted loads at a given speed and pressure. So I was on the horse back inversely....
Than what is the point of this chart? It tells me, than I should inflate my tyre from 5.6bar to 9 bar, if I would like to carry 4500kg (on a single tyre)?...or it is similar than I CAN deflate to 5.6bar my tyre if I only would like to carry 2950kg, because according to you, it says that at 5.6bar, I can carry maximum 2950kg (on a single).
So they are not the same?
If I CAN do that, why I should not to do that?...maybe the tyre wear will be less at 5.6bar @2950kg load, as at 9bar (same load)...regularry usage...
Thank you in advance your posts!

 

[CapriRacer]

".......Than what is the point of this chart? ......"

The chart is really supposed to be used by vehicle designers. It helps them properly size tires for their vehicles.

In passenger cars, there is a sticker that says what the original tire size was and what the proper pressure for that size is. The end user doesn't need to know anything other than what that sticker says.

Trucks are a different matter. I've never quite understood why trucks don't have a similar system - except to say that some trucks are not routinely loaded to the max, so in theory, they wouldn't require as big a tire (or as much inflation pressure).

But just as you have demonstrated, I think the charts aren't very useful for the consumer end of things. More importantly, it is common for folks to misinterpret them.

But to answer your question: It is quite clear that most users of truck tires use inflation pressures in a certain range - and the tire manufacturers know that - and design their tires such that tire wear is optimal at those conditions.

So if you follow the charts and add a bit of over capacity. In tire talk, we called it "reserve capacity" and I recommend a 15% reserve for passenger cars and light trucks, but I don't know if this is the common value for big trucks.

As I have pointed out, the wear curve is fairly flat in the vicinity of the optimal value. In other words, close is close enough. If your operation is fairly consistent, you can tune the pressure based on real life experiences (that is, removed tires) and adjust accordingly - keeping in mind what the minimum value would be.

But if your operation is NOT consistent, then you have to take your best guess based on the worst case.

 

[gunyu]

That's ok, i'm concidering the subjected chart(s) of course not with enduser's eyes, so I1m not a fleet owner, or truck driver, or worst: salesman.......I'm a mechanical engineer, working in development segment, but not tyre expert......so I desided to write here to gathering data, searching connection between tyre wear and tyre pressure/load/speed....But...people cannot imagine the case, that they CAN adjust the pressure in the tyre of their vehicle during its motion...just in time...according the speed and load demand....YES, they CAN do that...let's imagine that please....
so I'm looking for the caracteristic of curve of function between the tyre pressure and tyre wear in case of proper/optimum pressure (prompt pressure) for a given load and speed...because on internet I just find the similar curves according the plus/minus ~20% over/underinflated tyre pressure value according the given speed/load indexed given theoretic pressure...(what you meantioned, this is for the endusers, in this case, this is 9bar for this tyre)...but as I pointed out before, you shouldn't apply the same 9bar pressure for a loaded, and for an unloaded truck, because, there is an optimum pressure somewhere, according the load and speed...and NO, you shouldn't go anywhere with a relatively overinflated/under tyre, thanks for our imagination....
Allow me to quote you:
"The chart is really supposed to be used by vehicle designers. It helps them properly size tires for their vehicles."
So I sad this chart (again, the one titled as "Load and inflation pressure chart for single fitment use".) maybe good enough for me to estimate the proper/optimum inflation pressure for my purposes, so they help me to design something...so I think I didn't demonstrate the thing you think I did, just don't know the real functions here...still...but anyway, that wasn't my original intention to reveal the function between the curves I already have...but to reveal the characteristic of an under/overinflated tyre wear...the real one, and not the cosmetically curves on the internet, which belong to the nominal pressure inflated tyres....
Thank you your answers, thank you in advance!

 

[CapriRacer]

So if I am reading your post correctly, you are considering designing an on-the-fly inflation system that will adjust the inflation pressure in real time for the operating conditions with the idea of minimizing wear. What you need to make this work is a relationship between inflation pressure and wear - and whatever other parameters are involved, such as speed.

If you work for a vehicle manufacturer, then I suggest you contact your tire suppliers directly for information. Somewhere in the tire manufacturer's R&D will be an expert on tire wear, and he will be much more helpful than I can be.

If you don't work for a vehicle manufacturer, then you could approach a tire manufacturer, but I doubt if they will be forthcoming. A lot of tire knowledge is closely held secrets, and this area might be considered one of those. You'd have to be pretty convincing to overcome the natural skepticism people are going to have. I know I have trouble getting fairly simple, but odd tidbits out of tire manufacturer's toll free phone numbers, and I was in the business over 40 years.

And lastly, I'll bet there hasn't been much work to identify the parameters involved in instantaneous wear issues. I'm not sure how one would measure those things. I can imagine some computer modeling, but verifying the model might be problematic.

Besides, most tire wear occurs in cornering, so I tend to think that the benefit of adjusting inflation pressure on-the-fly would not be worth the effort. I could be wrong about this, and a good research project would help flesh this out.

So, whether you work for a vehicle manufacturer or not, I think this is something for which there is little or no reliable data - which means a joint research project.

Good luck

 

[gunyu]

I think this would be really the end of this topic/conversation...so I would like to thank you for your support, and all comments and infos here!
Yeah...I do my best to collect data, of course the company collaborates with tyre manufacturer...(but we just beat around the bush...yet...so firstly we have to put something on the table...)...and after (for years and years in time) there will be some project regarding this topic...to optimise the system for tyre wear...as I see the future....but of course kicking the ass of the mammut with an ant-leg, deffinetly means years and years to move forward...