255/40zr17 are the size of the tires for the rear,and they are falkens, i have a feeling that my noob brain got the wrong tire size because i am having that sluggish feeling at speeds around 50 and above, someone please help me out..

 

Sounds okay. I have 255/40 RT 615's and mine feels okay.

 

sorry i forgot to add these are on my ap2 rims

 

Which Falkens did you get?

The ap2 rear wheels are heavier than the ap1 rear wheels. If the tires weigh the same or more than the previous tires you had, then your engine is having to work harder to overcome that additional rotational inertia. Heavier wheel+tire combo = lower whp to the ground.

I know 615s are very heavy tires.

 

I really doubt the weight difference of the stock wheel to stock wheel + tire is going to make your car feel sluggish..

I think 255 could be a little wide on your stock wheels..

 

Underinflation?

 

The tires are inflated to normal psi, and you know what now that i think about it(Thanks to jefffrey song) 255 is wider and the walls on the tires cant handle it on the stock ap2's, and thats why is feels really sluggish on the freeway. i suck, but really grips taking turns on the streets

 

It may "feel" sluggish because you're actually gripping the road. The 615s have a wider contact patch than the stock RE050s. And the obvious reason is that wider tires weigh a bit more and the rotational weight comes into play. You'll be faster through the turns because you're gripping the road better and can maintain better speed but you're going to lose out on the straights. Wider isn't for everyone.