New Back Tires Causing Steering Issue
 

I'm at 25K and finally had to replace the back tires. I went with Yokohama YK580s, but since the front tires still have plenty of tread I did not replace them. After taking a drive to test the new tires, I'm getting a back and forth steering motion at higher speeds, very unnerving. I didn't have this before with the back stock tires, even in their worn state. Also, just passing a car on a straight away, I get the VDC light and the same shaky steering. Anyone with an idea what this could be?

You HAVE to run a matched set of tires (Same brand and model) or else you are going to run into issues like you are having now.

Mercy - a VDC at high speed in a straight line?. You sure they're lugged up tight and centered? Front and back? I just don't see properly sized tires from the same performance/speed category weaving back and forth when you are running in a straight line.

There's a chance they could have been insecurely fastened, however you'd be surprised at how bad a car can handle when you mis-match tires. Especially a summer compound and an all-season compound.

Its the tires. Match the fronts with the rears and you will be fine. Needs to be same brand and model imho.

Went back and spoke with tech at Discount Tire who did the install. Seemed knowledgable and said he put the same tires on his wife's car (Lexus) a few months back and it felt the same way the first few days but now they feel fine. If it doesn't correct itself over the next week they agreed to put different tires on the back or I can obviously choose to buy new YK580's for the front also. Then I'll know it's not a mismatch problem, we'll see. But I'm also amazed that I get the VDC light in a straight line pass with new back tires. I never got this even with the old stock tires with 25K on them.

It's definitely due to the mismatch... I can tell you that. The car is unsafe with the summers up front and the all seasons out back, so don't push it.

I know from experience, it is the tires. I went with hankooks on the rear and stockers in the front. Downright scary at highway speed. Replaced the fronts with matching and voila, problem solved. Good luck.

good info. you guys are life savers :ugh2:

tire size
 

Just my $0.02 Each tire manufactors over all diameter is different, even if the size on the side wall is the same. hope this helps :tiphat: