jpark

i did several searching but couldnt get the right answer, so here i go with a new thread...

i recently picked up and installed a set of ap2 v1 wheels, with front tires 225/45/17 and rears 255/40/17, all tires have lots of tread left.(the car is stock height, stock suspension)

however, i immediatly noticed the wobbleness and the unstable feel of my car when i drove.
for example, im on 3rd gear at 3-4k rpm and if i give it about 90% of gas, my car slowly shifts to the right like its changing lanes, and when i let go, it stops shifting... so if i want to change lanes i can just give it a full gas and it will change lanes for me to the right by itself -__-

i didnt notice anything like this with my previous ap1 wheels with front 205/55/16 and rear 225/50/16... it drove perfectly fine.

now im just wondering, would air pressure be the main cause here perhaps? whats the average air pressure for street use? 32-34psi i heard?
should i get an alignment? i heard something about u.k. spec alignment?

thanks, still a learning s2k noob

npham

Check your air presure, that fixed it for me.

s2000ellier

Not sure if switching from a 16" to a 17" wheel would change the suspension geometry but if it did, you should check the alignment and get it adjusted if needed. Also, incorrect tire pressure can cause what you are describing.

Here is the UK alignment sheet:

bbss2k

S2's are very sensative to tire pressure and camber wear. Check your tire pressure

DeRosa

Yes !
I bought a used S2000 and found that it was as squirrly as could be in the rain -- I was terrified to drive it over 50 on really wet roads.
An alignment smoothed it right out. It is the best money I ever put into a car. It had substantial positive camber on the back, among other things, before alignment. After the alignment, driving in the rain isn't much different than dry roads. Do it!

Billman250

Something is up with the rear tires.

Pressure is the number 1 culprit. Rear tire brand, size, pressure, and amount of wear must match. if one is worn a little more than the other it will never be right.

Temporarily switch the rear tires from left to right, if it pulls in the opposite direction under accel it is definitely the tires.

Check presure with a good gauge.

RedCelica

Honestly, I'd have them balanced and have an alignment done.

Billman250

Balance and alignment is a good idea, but that is not your problem.

It is 100% the tires.

SpitfireS

Even if the wear of your (2nd hand tires I assume going by your comment "lots of thread left") tires is perfectly equal left/right per "axle", they were most likely worn-in on different alignment settings than your car.
IOW they may need to wear in again > takes miles.

Did the seller mark the rotation or position on the wheels/tires?

Check the pressure with cold tires = not drive on them before you check.
Also, if one side ( front is also a side ) of the car is in the sunshine for a while, the warm side will read higher.
S2k's are picky when it comes to tire pressure.

teanza

it is absolutely the tires, either pressure or a lack of parallelism across the rears......