Tyre Friction Coeficients on official vehicles, are they accurate?

Capkirk · Jul 30, 2019

default0.0player said: ↑

Older sports cars have far worse weight distribution, just test this.
Put the same tire onto the 200BX and the Barstow. Choose the Street Tuned and the Nightsnake, put Clockwise 17X12 Rear Wheels and 285/35R17 Sport Rear tires. In 0~60 mph test, the 200BX is slightly faster despite much higher weight/power
--- Post updated ---
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Sorry, when I said the 2019 Prius can out-corner slightly older sports cars, I meant stuff as recent as 2015 model year cars. The 2019 Prius will beat sports cars less than 10 years old at low speed corners purely because of it's tires. I am aware that ladder frame, live axle muscle cars can be easily beat by any high end modern car, due to live axles and chassis flex ruining any grip they might have. I brought up the 2019 Prius because it is beating cars of it's era, that are several classes above it, purely because it was designed to use new tire designs. If you give those slightly older cars the same tires they will beat the Prius like they should.

NGAP NSO Shotgun Chuck · Jul 30, 2019

aljowen said: ↑

Suspension geometry (and vehicle handling) often feels like a dark art to me. For example, it was only the other day that I found out that fitting wider front tyres to a front engine rwd car can help to mitigate oversteer. Not only does it make the front end a little less twitchy, but once the limit has been exceeded, it make it easier to catch the car and bring it back in line. I was aware that moving towards square tyre setups had advantages (as well as disadvantages), but it wasn't until I had done some testing that I realised how much front tyre widths affect the rear end.

My understanding is that you don't really gain grip by lowering a car. However, you do change its handling characteristics. For the sake of simplicity, I am going to assume lower with correctly adjusted suspension for said ride height and surface.

So you get less suspension travel for pitching and rolling under accel/decel and turning, this will affect how the car transfers it weight, often allowing the car to settle more quickly after an input.
Often you will lower your roll centre. You can look up roll centre if you want a proper description. But in effect lowering the car will change the direction that any wishbones/links are angled at, especially in a double wishbone setup. Lower roll centre also affect weight transfers and has a surprisingly big effect on vehicle balance and handling dynamics.
Ride height is incredibly important for cars that are running down force too. Since they need to suck themselves to the floor.*
Many suspension designs will actually change the alignment of the vehicle as they progress through the travel. If you start off further into that travel because you are lower, it will change how that setup behaves.

When you lower a car, you can actually be making some very major changes without realising it.

*but as @default0.0player mentioned, beamng does not fully simulate aerodynamics. That means ground effect is not simulated at all, so diffusers don't work. That said, similar affects can be achieved by placing "fake" wings where a diffuser would be found etc.
Click to expand...

default0.0player said: ↑

Older sports cars have far worse weight distribution, just test this.
Put the same tire onto the 200BX and the Barstow. Choose the Street Tuned and the Nightsnake, put Clockwise 17X12 Rear Wheels and 285/35R17 Sport Rear tires. In 0~60 mph test, the 200BX is slightly faster despite much higher weight/power
--- Post updated ---

For a given splitter/diffuser geometry, the lower the ground clearance, the more the downforce. "Fake" wings does work, but ground clearance doesn't has any effect to it.
View attachment 574975
In the above picture, the lower the ground clearance, the ligher the V2, the lower the P2, the more the downforce.
View attachment 574976
Since aerodynamic parts are calculate separately, removing the bumper, trunk or window can actually reduce drag
Click to expand...

If I remember correctly, Kerbal Space Program has an aerodynamics model broadly similar to Beam's. Someone made a mod that switches it to real fluid dynamics, but it absolutely murders FPS. Now since KSP is mainly dealing with spacefaring vessels, I'd hazard a guess that the real-aerodynamics mod doesn't really bother with car-relevant things like ground effect, slipstream, and wake turbulence, or at least not in a very refined way.

Yeah, trying to properly simulate aerodynamics in Beam would bring anything short of a supercomputer to its knees. Plus, some "short cuts" would still be necessary as Beam's collision meshes aren't detailed enough to properly simulate "little things" like door handles or the bumps and ridges of old-style window moldings.

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