STEVEW3765

Hi to all. Hope everyone is enjoying the olympics. So, I finally replaced my rear tires today and had a badly needed 4 wheel alignment performed. Took it on a nice hwy straight away and felt comfortable to run over 100 mph for an extended period at last. However, I did notice the front of the car felt as though it was or wanted to jump around a bit. Is a steering angle calibration needed now or shocks struts. Or is this just a nuance? Thank you.

SoCal C2S

Edgy01

The 997 simply does not like to drive straight on the freeway. Whenever you replace tires always follow up with a four wheel thrust alignment.

Petza914

Mine drives dead straight, even at high highway speeds with 2 fingers on the wheel. I'm running an upgraded suspension with coilivers and GT3 alignment settings though, so maybe that's the difference.

okbarnett

need to check tire pressure. The last guy that bought tires had 90 lbs in them. Also new tires track the road better and will feel different untill they get worn in

user 72902

jll1011

Let is know what the tire pressure is. I have found that it is rare that the tire shops get the proper inflation pressure. Could be cause as stated.

STEVEW3765

Ok. I might not have explained correctly what is happening. I replaced my rear tires and had a 4-wheel alignment done. When I drive the car at high speeds or any speed above 60. The front end is loose as Sh?@! I doubt changing the rear tires had anything to do with it. Perhaps the rear tire and 4-wheel alignment that I knew it needed since I bought the car a year ago merely exacerbated this underlying issue. So, question now is. Where to start. How can tighten the front end down. Thanks

Petza914

Are you running the same make and model of tire on the front and rear? Are the new rears the same make and model as what you removed?

STEVEW3765

no and no

Petza914

... and there's your issue. Change the fronts to match the new rears you've just installed.

jll1011

STEVEW3765

thank you!

bhvrdr

there's a bit more information we need in order to help you out.

first itd be very good to know what are the exact sizes and the brand and model of tires on your car both front and back.

second what are your air pressures?

third do you have a copy of your post alignment specs?

finally it would be best if you could describe exactly what loose means to you.

in racing the term loose in front means understeer and loose in the rear is oversteer. Im assuming that's not at all what you're meaning because you're driving straight ahead.

sometimes people mean loose when it feels like the suspension is not properly connected so you feel a disconnect between the steering inputs and what the tires are doing or possibly even a knocking around from the front suspension.

Or you might be meaning loose as in the car is following ruts in the road which is better known as tramlining. That's when the front tires seem to follow the crown or the natural indentations or ruts in the road and it feels like it's hard to keep the car steering straight ahead.

mike

ltcjmramos

I agree with Pete, but not only do you have mismatched tires, but, I think, more significantly, you have rear tires with more relative grip.