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LFS tyre model?
(66 posts, started )
Nice video
but when S3 comes out it will be more realistic than this

Interesting that about surface temperature in LFS, never noticed that. Learn something new every day
@Dandy Dust,

One of the best posts read. So much beauty in your words.

Everage (average) computing power my friend is huge today.

Clean code that takes advantage of this power is no where in this world.

Multi threading is the future and after the creation of quality compilers, programming hardness every day is passed to the logic of splitting things apart in software development.

Somewhere here is the loop hole Mr. Scawen has entered.

He needs (fun,way of thinking) to create a perfect code in an industry optimised for mass production. This is a lonely road and thank you Sir for choosing this road vs the easier ones.

I wish him lfs s4 being created by his kids :-) for our kids, in a better world.
My sig says it all.
Interesting thread. It also goes to show that tire physics are extremely complicated.

Quote from tristancliffe :In real life I always set my best lap after a few laps on a set of tyres.

Quote from Meanie :
As I said, ask any endurance team driver about this.
For some reason, older tyres on LFS, are a lot grippier (and therefore, faster) than brand new tyres.

Any endurance (or anyone really that uses his tyres near the point of plain running out of rubber on them) driver to comment on this?

I know Tristan has way more real-world racing experience than most and I am sure he's correct, but it's pretty obvious the reason why the best lap comes after a few laps is tire pressure and temperature. For a real race, a crew chief will set the tire pressure to be less than optimum to allow for expansion when heated. That means that there is an optimum temperature/pressure where the tires will work best and it will take a couple of laps to hit that. Past that point, usually enough tread has worn off, and with the heat build-up, you'll usually never hit that optimum point again with that set of tires. (dependent on setup and other factors)

For real-world qualifying, the tire pressure is often set higher than for the race so the tires come to optimum temperature and pressure right away and they hit that sweet spot for a lap, maybe two, before the tires are done. They'll often reuse those tires for the race as "scrubbed" tires and they'll work just fine as long as the pressure is set properly for a long stint.

All of this is dependent on the setup of the car and the conditions, obviously. In endurance racing, you often hear drivers say that the tires were great all the way through the stint. This means the tires are good quality and the setup on the car was correct for the driving style and conditions. But so many other factors do come into play. I would suspect that the tire diameter has little overall affect on the results.

In LFS, I've only a few times noticed that I'm driving better laps near the end of a stint than the beginning. I suspect it has more to do with car setup and weight (less fuel) than it does the tires "gaining" grip. But that's my opinion.
Quote from DANIEL-CRO :Not truth, try brakeing with locked wheels. Speedomter goes to 0 (or close), but Aonio still shows speed (your real)

Svaka cast-respect for this
I drove a couple of endurance races and I have always made ​​PB at the end of stint if you do not count the HL laps. Why? Well, because at the beginning of a stint tires easily warm up. At the end of stint tyres are quickly cooled and it is possible to enter much faster in turn and you do not have to worry whether you overheat the tires and if you have to drive slower next five turns.

This applies only to R tires (R1,R2,R3,R4)
Quote from rageshgr :1) A worn out tire due to its lessened radius, will have lesser mass and more importantly lesser moment of inertia. So it is easier to rotate that wheel with the same torque. This I am sure has implication on acceleration. Hence the reduction in linear velocity due to diameter decrease and increase in angular velocity(RPMs of the tire) due to lessened mass and lessened moment of inertia may try to cancel each other

You can work this out. Acceleration can be calculated by a=f/m, where m is this case is translational inertia, rather than simply mass, and force is engine torque over wheel radius.

I took my X-Type as an example, comparing new tyres to those with a full 8mm of wear, the car ends up approximately 2% faster in 2nd gear (higher gears give a larger benefit as the engine inertia tumbels).

It looks like it's always going to be that the vehicle accelerates faster as the tyre wears (at least for typical values). I've attached a spreadsheet you can experiment with. The wheel inertia calculation is very simplified but it will do for now. I could make it generate the wheel masses and inertias for worn and unworn but it's too late and I'm very sleepy right now.

Quote from rageshgr :2) Theoretically this lessened mass and lessened moment of inertia of the wheel should improve top speed too I believe, hence trying to cancel out the reduction in speed due to lessened diameter. But I am not sure about this second point.

Umm.... no. The only effect on top speed will come from the changed engine velocity and thus power output.
Attached files
Acceleration with tyre wear.zip - 2.5 KB - 169 views
Hey that is Cool work dude! Yeah glad ti know my theory was experimentally tested too. So acceleration increases. Interesting. But as u said since top speed does not increase, aa scawen mentioned, the error in speedo due to lessended wheel diameter persists i guess.
Interesting study Bob, hope Scawen will learn (if he already didn't) from this how tyre wear also affect to acceleration quite a lot

BTW Tonight I dreamed how Scawen implemented that skin colour also affect speed, acceleration... example end of your car is black, and front white, we know that black colour absorb heat, while white colour reflect light (heat). So it's warmer at the end of your car, that means higher pressure that is actually pushing you forward... But thats just dream
While it's really nice calculation, it's missing quite a lot.
It shows effect of less mass a wheel has, but pure inertia is only one portion of energy needed to spend to accelerate car.
Add rolling resistance of tyre, and ofc - resistance of going thru air, etc, etc...
So in the end, difference is miniscule.
While it's interesting in scientific approach, in simulator case (such as LFS), it can easily be ignored.
Quote from DANIEL-CRO :
BTW Tonight I dreamed how Scawen implemented that skin :

Rofl. Did you also dream that, when using matte paint, it produces more turbulence and hence the car is less aerodynamic? Lol
Quote from rageshgr :Rofl. Did you also dream that, when using matte paint, it produces more turbulence and hence the car is less aerodynamic? Lol

I guess my head left that for another day (night)
Quote from Nick7 :Add rolling resistance of tyre, and ofc - resistance of going thru air, etc, etc...

Intentionally. For the purposes of this comparison, rolling resistance and air drag are identical, thus while the acceleration figures given are too high, it will reduce them both by the (almost) same amount, so it's still acceptable to compare the differences between them, which is what we're interested in here.

Quote from Nick7 :So in the end, difference is miniscule.

If you add in an arbitrary resistance force (comparable to travelling faster), you'll see that in fact, the absolute acceleration benefit increases (albeit marginally), and the relative benefit can increase significantly.
One of the most interesting threads ever, in this forum.

The tyre model is alpha og omega for a simracing simulator and I just can`t wait for a realistic model.

The coding issue :

I still remember what they did with the Commodore 64 and what great programmes that were created on this "breadbox". If Scavier can come close to that quality of programming, I can wait a bit longer

LFS tyre model?
(66 posts, started )
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