Need Tire Help

[Michael Brown]

Hi there. I need help on tuning tires for sim racing. My questions are:

-What is the optimal tire temperature for touring cars and open wheel cars?
-What is the optimal tire pressure for touring cars and open wheel cars? In Psi and kPa, please.
-How does graining work?
-What should the difference in temperature be on the outer, middle, and inner part of the tire?

 

[Dennis Phelan]

I just can't rate these posts. They are all liked, winners, informative and friendly!
Thanks for the insight on these aspects of sim development, I just drive.

 

[Jempy]

Interested in reading them ... as I'm always curious, but ...too long to read for the moment. .. a bit lazy these days.
Always interested when specialists like Chronus and Kenneth are debating and giving explanations.

 

[Kennett Ylitalo]

Well, i'm not a vehicle specialist, i'm primarily a track designer. But those go hand in hand, one needs to test tracks with all vehicles out there and sometime the fastest way to test something was to mod the vehicles a bit (usually that means just putting more power and/or varying tire grip, there is just not enough time to drive 1h sessions to see what it is like with low grip) But over time, a bit of study, the physics engine started to make some sense. And of course, just having fun like trying to model jet engines or electric motors. That GP2 mod is really my first real try, as soon as i noticed that SimBins Formula RR was sooo close to GP2 dimensions... I just had to try and the results were so positive, i sent it to few guys to test and the feedback was so good that.. well, i have to keep going and once the suspensions geometry was fixed to use the actual dimension, telemetry started to show values that fit... Specially tires that actually react on how you drive, pushing the front end on just one medium speed sweeper and boom: tires gone for the rest of the lap..

So, you see, it's not full blown scratch built mod, i haven't got the
talent to model complex models from scratch. But SimBin has given the permission mod their content freely, as long as we don't release them to other titles (this applies to everyone, it really is 100% free to mod anything inside the game now)

 

[Chronus]

The genre (racing simulation) is (inevitably) evolving. There will come a time - who knows, AC: Pro Racing, Project Race-CARS, or rF4 get released by then - when very few will be launching rF or Race07.

Right now, though, both have a lot of unconditional fans. Fortunately.

Some videos showcasing how good Race07 is...if people can see past the gfx:

[These videos were initially private, intended for a demonstration to a 3rd party. They were a bit rushed into existence, so they're not as good as I'd intended.]

 

[Justin Swan]

I've always felt Race 07 (as well as Race Pro) feels realistic when driven right on the limit. Anything less than that then it feels a bit cranky.

 

[Chronus]

I've always felt Race 07 (as well as Race Pro) feels realistic when driven right on the limit. Anything less than that then it feels a bit cranky.

[Not talking about Race Pro, though.]

Well, as with the videos above, my focus is not "SIMBIN cars". It is solely on the potential that GTRE (really, the potential of the physics engine underneath, pMotor2) offers.

In order to understand that potential, the original physics calibration needs to be dropped. Period.

Default/original physics in all SIMBIN sims (from GTR to RRRE) is designed with one thing in mind ONLY: to appeal to the widest audience possible, not to hardcore simracers. It is, as they say, a business, "not a modding team".

The physics calibration of WTCC/STCC cars is acceptable (with the exception of inertias).

Regrettably, the same mistakes (the kind that the RSC guys spotted and discussed some 7 years ago) keep surfacing over and over in GT cars, from GTR2 all the way to the Ford GT in RR:
- cars with excessive downforce (and bad CoP's, and wrong Aero distribution)
-tire wise, unnecessary dropofffunction choices, and many many wrong items (slip curves,load curves, grip coeffs, springyness, damper, speedeffects, rollingResistance, street tires slip angles applied to GT slicks, inconsistent, incomplete tire temperature generation and management)
- ridiculously low inertias (in some cases, 54% lower than it should)
- badly calibrated springs (no attention whatsoever to natural frequencies), most cars having improper ratios front to back
- badly calibrated ARB's, with also unrealistic ratios front to back

Cars with as many errors can't be, and aren't, realistic. But they do appeal to different types of simulation gamers (and they sell the impression of some realism, which is a neat trick).

IMO, that's sad. If you model them properly, you'll have a different learning curve but people will have fun and have intense races against either the AI or human opponents.

Ultimately, the decision to dumb down the physics to appeal to more gamers ends up hurting SIMBIN when new competitors appear.

 

[Kennett Ylitalo]

Agree wholeheartedly on the post above (inertia, aero, suspension, tires, all of it, usually very close but dumbed down. Like aero on open wheelers, lower drag than what should be, ay way lower, that gives the user more wing angle and thus more downforce. Top speed is then limited by rolling resistance of tires... Inertia tha gives a lot of mass and less inertia = more load on tires, less forces needed to change directions, ie higher grip with better cornering, balanced with super slow tire heating that is in turn balanced with too little air to thread temp.. Suspension system that rewards on softer values than what should be possible and still the car is not bottoming down, with decreased friction on the floor when it does etc etc)...

Fortunately, via modding one can make the simulation acceptable. Not perfect, adequate but enough that the talk of Race07 not being a real sim can be forgotten.

 

[Chronus]

Like aero on open wheelers, lower drag than what should be, ay way lower, that gives the user more wing angle and thus more downforce. Top speed is then limited by rolling resistance of tires... Inertia tha gives a [...]

Quite true.

All those things have devastating cumulative effects on any simulation. Tell you all, give us modding tools for AC and allow us to design and input "popular, wide audience" physics calibration (such as that used in almost all SIMBIN cars) and I guarantee that we can wreck AC just as easily, rendering it "arcade" or "NFS-type". All the "internet syndrome" experts out there would cry and tear their hair out, but that is an undeniable FACT (I have seen it done to 2 professional simulators commonly used by a few F3 and prototype teams).

iRacing itself has had some trouble (with people calling it a "failed sim" on account of a handful of cars) due to physics calibration issues and only the membership pressure made them correct the problems within a relatively short time span.

Fortunately, via modding one can make the simulation acceptable. Not perfect, adequate but enough that the talk of Race07 not being a real sim can be forgotten.

I wish that were so (the talk about Race07 not being a real sim left behind us), but a lot of "simracers" base their opinions on myths spread by people protecting their interests, or worse, on the headlines marketing professionals cook to boost the sales/membership/investment of their products (to the point that even modders like Niels lose their patience and have to correct one of these "internet experts" or their followers in regards to sim-physics or rFactor).

Race07 is a good "platform" for modding. Pick the GT cars in GTRE and dare to drop the original content of the physics files; follow the guidelines set by the RSC guys to the letter. Just by doing this (even without incorporating any data from research or RL data), you'll see a gratifying transformation of Race07/GTRE.

From what I have seen, the same can be said about openwheelers or production cars.

Sadly, due to the "business orientation" behind all SIMBIN products, most people will never understand how great a sim this is.

And I am 100% sure on this, the same is happening with RRRE/DTME, problem is these are not moddable so we can do squat to improve them. Lost opportunities...

[Paraphrasing MLK in our little simulation corner: I had a dream...that SIMBIN allowed some of us to pick their latest "Experience" sims and have a go at their models. Imagine that, together with what they already have: real time reflections, better shaders, improved netcode. Imagine that...]

 

[Kennett Ylitalo]

Can you me towards those RSC "guidelines"? Links etc.There is a possibility to convert all default content to sort of "pro-mod" now the content is managed differently..

R3e would amazing simulator with real life values, it's engine is really wonderfully done, great optimization and good graphics.. They did some changes on personnel to get "back to basics" but the base business does not really allow for unforgiving simulation..

 

[Chronus]

PM me a usable email and I'll send them your way. A lot of "meat", eh.

 

[Kennett Ylitalo]

PM me a usable email and I'll send them your way. A lot of "meat", eh.

Funny, i was just writing that PM

 

[Kennett Ylitalo]

@Chronus : bumb, sent you my email address, it's in profile post (for some reason, one can't PM you..)

 

[Chronus]

Hi, Kennett. I have received PM's from another RD member in the last few days. So I don't know what's happening.

I visited your profile posts, but haven't found your email.

--

Ah, found it on MY profile. Sending it soon.

 

[Kennett Ylitalo]

Yeah, it's weird, i can't invite you to discussions.. Don't know why.. I received your PM thou, so it must be one-way street..

 

[Slalom823]

Does anyone know if the temperature spread mentioned earlier in this thread for the untouched race 07 physics applies to the current game stock car extreme tires? As in will 85 85 95 be better for grip and tire wear than 85 90 95? If so is this normally done by less pressure or less camber? Also should tire temps be taken on straights or actually mid turn? Thanks!

 

[Cristian Haba]

@Chronus @Kennett Ylitalo these are very informative posts, most of the info talked about here is a bit over my head but it cements what I've suspected for a long time regarding new sims. Only I find AC to be the best one for me atm. What's your take on it?

Further, since I'm looking to broaden the sim spectrum I cannot come to terms with RRE mainly due to the lack off feedback the tires/car gives via their current FFB model. The game really suffers from that and it's borderline unplayable for me. Would you guys have any insight on that game motor that would help with ffb settings.

I'll give this another read and most likely get the simbundle just to try some of your mods and physics tweaks.