I find it a bit tricky with sharing tuning setups for Forza because there's typically a broad range of possible upgrades. A tuning setup for one configuration might not be remotely viable for a car with a totally different set of upgrades. You can take a low-end car and potentially heavily upgrade it to double or triple its original stock performance. You can take a Volkswagen Beetle and basically make it a Formula 1 car disguised as a Beetle. I personally prefer trying to keep cars somewhat close to original so some essence of the original car remains, but this isn't always plausible, like if you're in a car with 389 PI (Performance Index) and you're in a race against cars at around 600 PI. Even on a low difficulty setting, you're probably going to get crushed.
Still, I'll try posting a few, probably based on being upgraded with little more than what's necessary to actually tune it.
2018 Ford Mustang GT
696 PI
3339 pounds
52/48 weight distribution
RWD
general tune
Tire Pressure: 33.5 front, 31.5 rear
Wheel Camber: -2.0 front, -1.2 rear
Toe: 0 front, 0 rear
Caster: 5.8
Anti-roll Bars: 21.1 front, 18.3 rear
Springs (pound/inches): 765.2 front, 720.6 rear
Ride Height: 40% front, 40% rear
Bump: 4.3 front, 4.0 rear
Rebound: 7.0 front, 6.5 rear
Roll Center Offset (inches): 0.8 front, 0.4 rear
Anti-Geometry: 24.2 front, 15.5 rear
Downforce: medium front, medium rear
Brake Balance: 53%
Brake Force: 100%
Rear Differential: 55% acceleration, 25% deceleration
1987 Ford Sierra Cosworth RS500
511 PI
2685 pounds
51/49 weight distribution
RWD
general tune
Tire Pressure: 30.0 front, 28.0 rear
Wheel Camber: -2.2 front, -1.2 rear
Toe: 0 front, 0 rear
Caster: 5.6
Anti-roll Bars: 18.7 front, 18.2 rear
Springs (pound/inches): 611.3 front, 599.2 rear
Ride Height: 40% front, 40% rear
Bump: 4.2 front, 4.1 rear
Rebound: 6.9 front, 6.6 rear
Roll Center Offset (inches): 0.8 front, 0.4 rear
Anti-Geometry: 21.0 front, 10.1 rear
Downforce: medium front, medium rear
Brake Balance: 53%
Brake Force: 100%
Rear Differential: 55% acceleration, 26% deceleration
2018 Ford Mustang GT
696 PI
3339 pounds
52/48 weight distribution
RWD
wet race tune
Tire Pressure: 34.5 front, 32.5 rear
Wheel Camber: -2.0 front, -1.2 rear
Toe: 0 front, 0 rear
Caster: 5.8
Anti-roll Bars: 13.4 front, 11.6 rear
Springs (pound/inches): 551.6 front, 519.5 rear
Ride Height: 50% front, 50% rear
Bump: 3.7 front, 3.4 rear
Rebound: 5.9 front, 5.5 rear
Roll Center Offset (inches): 0.4 front, 0.4 rear
Anti-Geometry: 24.2 front, 15.5 rear
Downforce: medium front, medium rear
Brake Balance: 53%
Brake Force: 85%
Rear Differential: 55% acceleration, 25% deceleration
1987 Ford Sierra Cosworth RS500
511 PI
2685 pounds
51/49 weight distribution
RWD
wet race tune
Tire Pressure: 30.5 front, 29.0 rear
Wheel Camber: -2.2 front, -1.2 rear
Toe: 0 front, 0 rear
Caster: 5.6
Anti-roll Bars: 12.7 front, 12.3 rear
Springs (pound/inches): 440.7 front, 432.0 rear
Ride Height: 50% front, 50% rear
Bump: 3.6 front, 3.5 rear
Rebound: 5.8 front, 5.6 rear
Roll Center Offset (inches): 0.4 front, 0.0 rear
Anti-Geometry: 21.0 front, 10.1 rear
Downforce: medium front, medium rear
Brake Balance: 53%
Brake Force: 85%
Rear Differential: 55% acceleration, 26% deceleration
2018 #23 Ruman Racing TA Corvette
900 PI
2902 pounds
49/51 weight distribution
RWD
general tune
Tire Pressure: 30.0 front, 29.5 rear
Wheel Camber: -1.6 front, -1.2 rear
Toe: 0 front, 0 rear
Caster: 6.1
Anti-roll Bars: 15.4 front, 16.0 rear
Springs (pound/inches): 715.2 front, 759.4 rear
Ride Height: 40% front, 40% rear
Bump: 4.4 front, 4.6 rear
Rebound: 7.1 front, 7.4 rear
Roll Center Offset (inches): 0.8 front, 0.8 rear
Anti-Geometry: 25.3 front, 17.0 rear
Downforce: medium front, medium rear
Brake Balance: 52%
Brake Force: 100%
Rear Differential: 51% acceleration, 26% deceleration
2018 #23 Ruman Racing TA Corvette
900 PI
2902 pounds
49/51 weight distribution
RWD
wet race tune
Tire Pressure: 31.0 front, 30.5 rear
Wheel Camber: -1.6 front, -1.2 rear
Toe: 0 front, 0 rear
Caster: 6.1
Anti-roll Bars: 12.2 front, 12.8 rear
Springs (pound/inches): 515.6 front, 547.5 rear
Ride Height: 50% front, 50% rear
Bump: 3.7 front, 3.9 rear
Rebound: 6.0 front, 6.3 rear
Roll Center Offset (inches): 0.4 front, 0.4 rear
Anti-Geometry: 25.3 front, 17.0 rear
Downforce: medium front, medium rear
Brake Balance: 52%
Brake Force: 85%
Rear Differential: 51% acceleration, 26% deceleration
2016 Lamborghini Aventador Superveloce
799 PI
3607 pounds
44/56 weight distribution
AWD
general tune
Tire Pressure: 32.5 front, 36.5 rear
Wheel Camber: -1.6 front, -1.2 rear
Toe: 0 front, 0 rear
Caster: 5.9
Anti-roll Bars: 12.0 front, 17.0 rear
Springs (pound/inches): 668.0 front, 902.8 rear
Ride Height: 40% front, 40% rear
Bump: 3.6 front, 4.7 rear
Rebound: 5.8 front, 7.6 rear
Roll Center Offset (inches): 0.8 front, 0.4 rear
Anti-Geometry: 25.6 front, 8.6 rear
Downforce: medium front, medium rear
Brake Balance: 52%
Brake Force: 100%
Front Differential: 38% acceleration, 16% deceleration
Rear Differential: 50% acceleration, 26% deceleration
Center: 63%
2016 Lamborghini Aventador Superveloce
799 PI
3607 pounds
44/56 weight distribution
AWD
wet race tune
Tire Pressure: 33.5 front, 37.5 rear
Wheel Camber: -1.6 front, -1.2 rear
Toe: 0 front, 0 rear
Caster: 5.9
Anti-roll Bars: 10.3 front, 14.7 rear
Springs (pound/inches): 481.6 front, 650.8 rear
Ride Height: 50% front, 50% rear
Bump: 3.0 front, 4.0 rear
Rebound: 4.9 front, 6.5 rear
Roll Center Offset (inches): 0.8 front, 0.0 rear
Anti-Geometry: 25.6 front, 8.6 rear
Downforce: medium front, medium rear
Brake Balance: 52%
Brake Force: 85%
Front Differential: 38% acceleration, 16% deceleration
Rear Differential: 50% acceleration, 26% deceleration
Center: 63%
2003 Porsche Carrera GT
900 PI
3178 pounds
41/59 weight distribution
RWD
general tune
Tire Pressure: 29.5 front, 33.5 rear
Wheel Camber: -1.7 front, -1.3 rear
Toe: 0 front, 0 rear
Caster: 6.1
Anti-roll Bars: 19.5 front, 19.0 rear
Springs (pound/inches): 630.2 front, 925.2 rear
Ride Height: 40% front, 40% rear
Bump: 3.6 front, 5.2 rear
Rebound: 5.8 front, 8.5 rear
Roll Center Offset (inches): 1.2 front, 0.4 rear
Anti-Geometry: 29.2 front, 15.6 rear
Downforce: medium front, medium rear
Brake Balance: 50%
Brake Force: 100%
Rear Differential: 41% acceleration, 31% deceleration
2003 Porsche Carrera GT
800 PI
3271 pounds
41/59 weight distribution
RWD
general tune
Tire Pressure: 30.0 front, 34.5 rear
Wheel Camber: -1.7 front, -1.3 rear
Toe: 0 front, 0 rear
Caster: 6.0
Anti-roll Bars: 18.3 front, 17.5 rear
Springs (pound/inches): 618.1 front, 907.5 rear
Ride Height: 40% front, 40% rear
Bump: 3.5 front, 5.1 rear
Rebound: 5.7 front, 8.2 rear
Roll Center Offset (inches): 1.2 front, 0.4 rear
Anti-Geometry: 26.9 front, 13.5 rear
Downforce: medium front, medium rear
Brake Balance: 50%
Brake Force: 100%
Rear Differential: 42% acceleration, 31% deceleration