I’ve got a 1970 RWD sports car and for some reason it loves having 235s in the front and 225s in the rear. If I try turning it around or making them both the same, the sportiness score drops at least two points. I figured it’s probably a suspension issue so I tried adjusting the suspension, then changing the engine from a V8 to an I6, but it still maintains this bias. I would expect it to prefer wider rear tires, if not even sizes. I guess I could leave it with wider fronts, but it’d be nice to know why it’s doing that, so I thought I’d ask on here to see if someone more knowledgeable can clue me in. So far this is the only car in my lineup that’s doing this.
Wider front tyres make the car understeer less. You should be able to solve the issue by using stiffer rear springs or anti roll bars.
Wider tyres in the rear usually only make sense if you have either a rear-heavy car, unsolveable oversteer or lots of power to put down on the road.
[quote=“Der Bayer”]Wider front tyres make the car understeer less. You should be able to solve the issue by using stiffer rear springs or anti roll bars.
Wider tyres in the rear usually only make sense if you have either a rear-heavy car, unsolveable oversteer or lots of power to put down on the road.[/quote]
OR if you want to look badass!!! 
[quote=“Der Bayer”]Wider front tyres make the car understeer less. You should be able to solve the issue by using stiffer rear springs or anti roll bars.
Wider tyres in the rear usually only make sense if you have either a rear-heavy car, unsolveable oversteer or lots of power to put down on the road.[/quote]
Hmm… Well, with 225/225, I went all the way to maximum rear spring stiffness (100,000) and raised sway bar stiffness until it stopped helping, but sportiness is still far lower than if I use 235 front tires. I’ve spent hours monkeying with the suspension, so that doesn’t seem to be it. The best I can get with 225/225 is 3.5 sportiness points lower than 235/225. 
Ok I tried switching the engine to aluminum and using tubular headers to reduce front car weight, and that did seem to remove the front tire width bias, but I still can’t get the sportiness score as high, so I have no incentive to make this change. lol
Sportiness score is one thing, but the real tests are in the bump graph, the yaw graph, and how fast it goes around the track. What happens to your track times?
Interesting. Yeah, the track times improve with just changing the tires to 225/225 and no other changes, but sportiness drops 3.5 points and the stats listed on the track page are all yellow, except for acceleration, which is red. The problem is, aren’t the scores what the virtual customers use to decide if they want to buy?
Maybe this chassis is too weight sensitive for what it is. My engine is already much smaller than what cars like this used in real life, and my 1955 and 1985 sports cars seem to be working fine.
I guesw it would help if you post a screenshot of he detailed stats of the sportiness screen when you changed the tyre width. So we can see which factors changed. He test track screen does not say everything regarding sportiness.
Something seems to be really weird if you have to use such stiff rear springs.
[quote=“Der Bayer”]I guess it would help if you post a screenshot of the detailed stats of the sportiness screen when you changed the tyre width. So we can see which factors changed. He test track screen does not say everything regarding sportiness.
Something seems to be really weird if you have to use such stiff rear springs.[/quote]
Could probably wait for the upcoming update in March, but here’s the screenshot. 
This is without any of the engine or suspension adjustments mentioned above. I just changed the tires from 235/225 to 225/225.
From what I see you are loosing grip on the front end while turning (lateral accel), you went from -3.7% to -7.4%. Basically your car is understeering in corners and wider tires let it grip more and make turns faster/more aggressively.
Yeah, but if I go 235/235 it goes down too, and throwing in a less powerful engine didn’t seem to help in this case.
try messing with your camber
Tried that already, from 0 to -3.00, leaving one the same while changing the other, then the reverse, etc.
You can also reduce the Swaybar stiffness in the front and make the springs slightly softer than you normally would, that gives more grip to the car (more roll -> more effective camber -> better contact area & more weight transfer) up front.
I’d love to have a look at the .lua to see if there is or isn’t something messed up somewhere. All the above explanations are reasonable strategies, though.