Let's discuss iRacing

no no no, defaults are grippy racing slicks, road legal semi slicks are the right tire for the road legal F40 s3

 

Question is...Is it better to drop the tyres down to 20 psi and drive carefully or 25psi and not drive carefully? Low PSI=faster tyre wear. Lap 2 and you have no grip left.

 

Your instincts are wrong then. Heat on straights is mostly from tire flex (try stretching an elastic, it'll get warm... no friction from anything, but it's absorbing energy so it heats up). Flex obviously happens across the whole tire, not just the part touching the ground. And heat is lost way more to the tarmac than to the air - air's a terrible heat conductor.

 

95% of the tyre is in the air and tarmac produces friction. Friction => heat.
if tarmac would cool the tyre down, the inner side of the tyre wouldnt be hot here:

 

I think that I bumped up the psi, I use only semis with S3

 

Thanks for the tip on the discounts - I renewed for 3 months so I could try it with CV1.

I'd forgotten what beasts iRacing holds. The Falcon V8 SuperCar is a handful and can be downright scary. I really like how they do their tranny/gearbox physics; I think it's the most convincing of any of the Sims and it adds a lot to the experience in creating the raw and dynamic atmosphere of true race cars IMO. Good stuff and the Rift support is definitely improved over the previous versions; there is more directional movement but, the animated wheel rotation and arm-movement is still limited.

 

Don't you mean the outer tyre?
When you corner, the weight shifts to the outside tyre, thus wearing it's grip levels more than the inside tyre.

 

Has anyone compared the new laserscanned Imola of theirs with that of AC? I do not use iR, but would be interested in opinions, for curiosity, Imola is one of my most-used tracks. And yes, I still suck at and enthusiastically hate turn 13-14... LOL

 

What? No. He said that tarmac cools the tyre, but it doesn't. When the car is going straight, the inner edge is hot, because of friction (or some other magic...). If tarmac would cool the tyres, the inner edge would be cold and the outside of the tyre would be hot.
Sorry, if that is not what you asked, but that is how I understood your question

 

Well if tire is 100+ and tarmac is ~35, then it will surely cool down the tire. Tarmac itself as material. He said that tire heats due to amount of energy stored in it, deformations, rolling resistance (friction). I guess tire heats up when the amount of heat transferred from tire to tarmac and air is lower than heat produced by stored energy.

I know from my studies that air is really bad heat conductor. But I'm not sure if there is wind, high speed air flow, I think then it becomes quite significant coolling element.

No expert here, eager to learn though.

 

They way I see it, it is just a matter of time.
Think of a point of tyre. Now think what percentage of rotation, this point, touches the asphalt and what percentage it's on the air.
Yes asphalt is better heat conductor than air but the way I see it, it touches it so much less than the air, that I would expect that the tyre would cool when on straights.
But this is for normal cars.
With high downforce cars, where the load on tyres increases as speed builds up, maybe the deformation of tyres acts in such percentage that heat transfer through air is way less.

All these are just thoughts.
In any case I trust more Aris on this and some infrared videos that we see from F1 cars.

Στάλθηκε από το m2 note μου χρησιμοποιώντας Tapatalk

 

There's also high speed tarmac "flow" though. It helps because the warm insulative layer is being removed, but that effect happens equally to both air and road. And "really bad" means, air takes 1/1000 as much heat as most solids. 30cm radius x 50cm wide slick has a surface area of ~1 square metre, so a contact patch of 10 cm^2 would be able to cool just as much as the 9990cm^2 that hits the air, ballpark estimate says 250-300cm^2 actual contact patch, so 25-30 times as emuch heat is lost to the pavement than to the air. That's without taking into account that the temperature difference affects heat transfer, so the tarmac has another advantage (since heat is generated in the bottom of the tyre, which is the part touching the ground, it can transfer heat faster than the relatively cool part of the tire in contact with the air). On the other hand it's a disadvantage because tarmac tends to be hotter than the air, but if someone with access to the numbers says the tarmac is the main thing, I'm completely willing to believe it.

Interestingly that F1 video confirms DK's original comment, which was that the outside of the tire stays warm on straights longer than the center because it's only touching the tarmac while cornering (esp. noticeable between the Lesmos). You have to squint a bit to see it cause the leaderboard's covering that part of the left tire though and since it's Monza I don't think the car has a symmetric camber setup.


If you watch IR cam footage of cars in corners you can see they leave hot trails on the pavement, I almost wonder if that contributes as much to "aero push" as the actual aero. You'd certainly get hotter tires if you stayed directly in someone's draft.

 

Very interesting post. I had something about that tarmac "flow" in my imagination, but it is kinda hard to imagine, if the tire which rotates very fast could be considered as touching surface constantly, in terms of temperatures. But somehow logical.

Now I also wonder if drafting car has more grip, hotter tires. My guess would be that it is probably a very very tiny difference. If person in front has tarmac 35°C, so how much hotter it could be for a drafting buddy. Sounds like interesting physics task here. My guess would be no more than 1°C hotter

 

my pro's for each off the top of my head (bare in mind its maybe 2 years since I played iRacing regularly.)

iRacing pro's

.great sounds
.tracks feel more like a real 3d space to me. no idea why
.lots of tracks
.proper damage
.proper starts

AC pro's

.more classic car choice
.the price
.public racing and more casual racing
.cats
.the price
.mods
.the price

 

Interesting post Stereo. I wouldn't have thought it worked that way at all. I would have thought the volume of air passing over the wheels would suck the heat out of the tyres way more than the transfer into the tarmac. I wouldn't have thought of air as a bad conductor when it's passing in volume?

 

Haven't played iRicing at all, but I guess you are talking about depth perception. Which creates sense of speed. I see somebody posting in facebook, that AC feels "slower" than some other titles. It was Nordschleife real vs AC comparison video I think. It wasn't hard to spot that IRL footage objects far in the distance seemed to be further, than objects in AC video. As well as track width, looked narrower in the distance RL footage. Somehow I doubt it is caused by FOV. I read VR gear gives amazing feel of depth perception.

P.S. Talking about AC and iR, I guess when AC came out it gave hell of a push for iRacing. And maybe rF2 too ?

 

I was under impression that the

chances that any onboard IRL cameras are using 43-45mm lens is very low (tha would be something like setting correct FOV or human eye) .. GoPro for example uses 14-28mm focal length (35mm equivalent) so that alone makes huge (extremely huge) difference in perpective ..

 

Iracing just like real life? In real life would you crash twice on Nurburgring and blow out the clutch?

In real life if a car was a hard to control, twitchy and crash prone would you buy that piece of crap? Or would you buy a car that drove butter smooth and was easier to drive a car you could push to the edge?

Harder is not more realistic if a sim is harder than real life it is a lousy sim.

That being said I do like Iracing it has its' good points and its' bad points. The graphics are weak, the physics are not the best, the interface is clumsy and outdated, however online multiplayer racing format is very good.

 

I don't know that it's depth perception you're describing. I think depth perception is related to binocular vision, I think focal length would have more to do with how far objects appear to be from each other in pictures and video. If you have a camera you can have lens with different focal lengths so a zoom lens might make things look much closer than they really are to each other.

It would be very difficult to make a picture taken in AC match up exactly with a real life picture. Even if you could position yourself in the exact same sport in game and in real life you'd have to copy the exact lens variables from the game into real life or visa versa.

 

I remember some of our knowledgeable folks here talking about how it is pointless to watch those FLIR videos. FLIR is only showing you the outer surface temperature.

You have to think about the entire tire, not just the surface. It makes plenty of sense that you can heat the tires on the straights with lots of negative camber, but then cool them down in the corners if not pushing it, and if the road temp is low.

Its become very apparent how tricky it can be to heat both front and rear tires to the proper temps since the official Tire Temp APP has come out. Certain cars are quite tricky to get the front and rear tires up to temp equally; you have be very aggressive in the turns. Waiting to turn till the very last millisecond and turning in extremely aggressively to get the tires near the limit to get some scrub (I believe) to warm the tires. If you don't do it right, you are either understeering and getting your fronts warm but letting the rears get cold, or are oversteering and getting your rears warm and fronts cold.