Idk if this should go here or wheel and tire, i figured i would get better responses here. Anyway i put on new 17s with lower pro falken ze512 tires the other day. The car is just on neuspeed sport springs. Anyway now the car feels like it has way more body roll in corners. That car was previously on stock wheels falken ze512 tires.

 

Are your tires inflated to the proper pressure?

 

Yes and lugs are nice and tight.

 

Incorrect butt dyno readings maybe? Meaning, could it possibly all be in your head?

 

No its definitely not in my head. Last night on the highway i felt the difference. The cars rear wants to always come out now. Tire pressure is perfect. Car just had alignment. Im thinking maybe because im using a lower profile tire now ?

 

But a lower profile tire i heard helps handling ...this makes no sense

 

hmmm... your rears are breaking loose. What kind of setup do you have up front? Seems like your front is not as beefed up as your back, hence the back breaking loose.

 

Just neuspeed sport springs (upgrading to koni/GC's soon). But before i put these wheels i had the stock wheels with falken ze512s all around and the neuspeed springs and it never did this.

 

okay, i just re-read. You said you upgraded your wheels to 17's right? You also mentioned that you purchase "lower end" tires?? If this is the case, then it's definately the tires.

 

No same tires i have Falken ze512's on both sets.

 

you're talking about 2 different things here, i'm a little confused.

there's body roll, and then there's "oversteer" as you describe it.

it makes sense that the body rolls more with lower profile tires, in that the sidewall is flexing less, and the suspension is compressing more. given that the overall grip levels are probably the same, or very close to each other, you've got a situation where the weakness in one part of your car's suspension has been shifted to the next component (soft springs/not enough roll resistance via sway bars).

 

Yes that makes sense