Because at the moment it doesnt, would be nice if it did

Quote from danowat :

Because at the moment it doesnt, would be nice if it did

this only makes sense if you are driving like 400-500 km-s, but for the general pick-up racer or non masters of endurance league racer this is of no importance.

and did anyone at all try racing for 6 hours or more twice, with different tyre pressures to see if it was already implemented?

Prove me wrong

Rolling resistance makes the car go slower with maximum throttle.
-> slower speed
-> engine rotates less per minute
-> with simple carburetor cars with throttle flatout the engine gets the same amount of fuel, regardless of little speed differences(?)
->rolling resistance doesn't have influence on fuel consumption per time, if you are driving at full throttle.

However, decreasing tire pressures (=increasing rolling resistance) means that you have more grip (when you are inside the area where you can get more traction by decreasing the tire pressures) during the short time when your traction is limited by power and cornering forces. But this "benefit of less pressures" turns into disadvantage when the traction stops limiting your acceleration. After that it just slows down your acceleration. After all, racing is purely accelerating on straights.
= engine has less power to use to accelerate the car because bigger portion of the total available power is used to overcome rolling resistance
But also
= you can drive more % of the time per lap with more throttle open
-> increased fuel consumption
Also
After some point, when decreasing the tire pressures, the additional traction increases the rolling resistance limiting your top speed
= shorter braking distances
= later braking points
= releasing the throttle later when starting to brake because less speed and more grip
= more grip to get back on full power earlier and quicker
= more % of the lap driven with more throttle
= increased fuel consumption

So you are saying, rolling resistance doesnt effect fuel consumption at full throttle, but does at other throttle positions? explain more please.

Come on, a little bit of common sense solves the issue.

If you drive your daily route, you're likely to drive it at speeds you feel comfortable with, rather than with x% depressed pedal.

Example: you drive a straight road with 60mph. With good pressured tyres, you need 50% pedal travel to keep the car at that speed. But with low pressured tyres, you suddenly need 65% pedal travel to reach the same speed, causing more fuel to be burnt and a noticeable drop in mpg.

Now under racing conditions, you drive that straight with 100% pedal travel, which means it uses maximum amount of fuel. The only difference between high and low pressure tyres is now, that the low ones result in a lower top speed, which means for the same amount of burnt fuel, you travel less distance, thus slightly worse mpg.

Quote from danowat :

So you are saying, rolling resistance doesnt effect fuel consumption at full throttle, but does at other throttle positions? explain more please.

If you drive infinite long straight with you foot down:

a) with "minimum" tire pressures
- you are going slightly slower because of the bigger rolling resistance
- you are still using as much fuel as the "engine can take or the engine injection systems () can deliver"

b) with maximum pressures
- you are going slightly faster because of less rolling resistance
- you are still using as much fuel as the "engine can take or the engine injection systems () can deliver"

Result:
per time you are using as much fuel in both cases because your fuel consumption per time is equal. Which means that if both drivers do a one 20 second full thorttle acceleration and the consumption is measured during this time, both use as much.

per distance you are using more fuel with less pressures because your car travels shorter distance during the 20 seconds (for example). Rolling resistance decreases down the acceleration -> less speed. If the drivers were set to drive 5km straight as fast as possible, the one with less pressures would use more time to drive the 5km because of the added rolling resistance decreasing the acceleration -> the average speed is slower.

When decreasing the tire pressures, after a certain point, you get slower lap times because you are losing speed on straights. That measn that your average lap will take a longer time. During that time you also use more throttle because of the extra grip. But you can't use that extra grip to your benefit because you lose it on the straights, because your acceleration is worse.

D'oh

Fairy nuff guys, I'll take your word(s) for it

Improvement suggestion DENIED!

Fair play, but we (I) still haven't proved if LFS fuel consuption is effected by tyre pressures (however little it may be)

Quote from danowat :

Fair play, but we (I) still haven't proved if LFS fuel consuption is effected by tyre pressures (however little it may be)

Then what are you doing posting? =P I think you have but you didn't do enough laps to verify.

There might be a chance to prove if LFS has this or not. With dxdiag (or something like it was) you could calibrate your throttle to 10% and try to measure how fast time you can get on the drag strip. If the time is slower with lower pressures, LFS has passed the test. If not, Scawen needs to release an incompatible patch in 5 secs. And it must include Ferrari F50 and Nürburgring too.

10% to make the difference more easy to notice and dragstrip because the user has the least chances to cheat

Without gearchange.

Isn't there an outsim parameter that would show increased resistance or something?

Tyre pressure does effect rolling resistance, that's easily noticeable. Try max and min tyre pressures in RB4 in the dragstrip, even though decreasing the tyre pressure increases grip, go below a certain pressure and your drag ETs start going back up again due to reduced velocity over the finish line.
Alternatively try getting the MRT5 up to top speed with min and max tyre pressures, there could be a upto a couple of digits difference.

We also know that (in S2) rolling resistances aren't directly calculated, rather the energy needed to heat the tyre is calculated, and this creates the rolling resistance.

Accleration is calculated by taking the driving force from the engine and reducing it by the resistant forces. We know fuel is comsumed (in LFS) by working out the energy required to create that driving force and using the calorific value for petrol.

So there isn't really a direct link between resistant forces and fuel consumption. But for the same fuel consumption, different resistances will result in the vehicle accelerating at a different rate.

Quote from Bob Smith :

We also know that (in S2) rolling resistances aren't directly calculated, rather the energy needed to heat the tyre is calculated, and this creates the rolling resistance.

How do we know this? (I know you don't usually talk out of the wrong end So where did this knowledge come from?)

This is the kind of thing I am talking about when I mention a "feature list". I could infer what you said, but I've never seen Scawen actually say it before.

Yes, that info came from Scawen's nifty fingers, I read that ages ago.

Having two threads on this same matter is getting confusing, but would it be any better if I merged them? Hmm.

I just posted results of an AI test with FOXs at BL1

http://www.lfsforum.net/showthread.php?p=280316#post280316

EDIT: To sum it up, fuel consumption does change with tyre pressure.