Put on new rear tires, now my car handles terrible! WTF?
 

So after 1.5 years of running with Continental ExtremeContact DW tires, my rears go bald. I change the rears only(with identical tires), and kept the fronts still had nearly 50% of tread left. Now my car handles like total crap with the rear end floating around like crazy causing the traction control to kick in all the time now.


Has anyone else ever experienced this? I've been driving for over 100 miles on the new rear tires, and they are still causing the traction control to activate all the time on fast corners. On freeway interchanges where I normally can drive 50mph, I can't drive more than 35mph without traction control flashing non-stop.


I already took it back to my shop to confirm they had the wheels balanced properly. Is it relatively common for new tires to require a long break-in period, or is there anything particular with the BRZ/FRS balance when just changing rear tires?


I should add that I'm running a staggered wheel setup on Work Emotion Kiwami's 245/35-18 rears & 225/40-18 fronts, & KWv3 coilovers. (My BRZ basically looks exactly like this Chargespeed car) Thanks for any advice.
http://farm6.staticflickr.com/5456/7...303a896a_b.jpg

Same tires as on it before?

I personally would have went with 4 identical tires, but I dunno if that would have helped you in your case. Sure the balance all is in check right?

Your back tires are taller than your front. Were your last set of rear tires that way too?

Ummm... what kind of tires did you buy? If you got some all-season radials with a 60,000 mile wear rating they're not going to stick like a good UHP tire.

this, our traction control thinks all our tires are the same total diameter,
idn how far out f&r have to be from each other to confuse the system though

http://www.1010tires.com/Tools/Tire-Size-Calculator <- could enter the sizes there to see how far out they are exactly

Give the rears time to lose the grease from the newness then try again. I had the same problem with a new set of S04's but after a few weeks they started holding like I expected.

Thanks for all the input. I should clarify that I replaced the rear tires with the identical brand & size tires as before.

Sorry, I stated the incorrect profile for the fronts... they are actually:
Front - 18x8.5 +38 with 225/40 tires
Rear - 18x9.5 +38 with 245/35 tires
(corrected original post)

These tires are Max Performance Summer Tires:
http://www.tirerack.com/tires/tires....remeContact+DW

Since I've double checked everything, I'm crossing my fingers that it just has a very long break-in period before the new tires start gripping like the worn-in fronts do. Maybe it's time to start doing burnouts!

well its winter now... :)

Not yet it aint. Oh god not yet!!!!!!!

I found it took nearly 1000 km of driving on my Xi3's before they gripped the way I expected. ABS kicked in stopping normally for a crosswalk on the way home from the tire shop it was so bad at first.

New tires don't stick well. And it's never winter in California!

Go burn some tire ;)

50% in the front? Either you're forgetting to rotate or you're having way too much fun...

Like someone said above its because your rear tires are new so there diameter is bigger than the front, this causes a speed differential between the front and rear tires, but also, when you go around a corner the outside wheels will need to spin faster than the inside and this could cause the ABS/Stability system to act up because you've exceeded it's maximum speed differential between all the wheels. Get all 4 tires within 2% of each others total diameter and you should be fine. It might only be a small total difference in height - say 1/8" - 3/16 to cause it act up. And also the new tires will be greasy as others have said which could be contributing to the problem.

Have you checked your tyre pressures?
Sometimes fitment centres pump new tyres very hard which could cause your problem.

Yeah


Check the air pressure. I got new tires one time and the car handled like crap. Checked the air pressure and it was 80 psi!
IDIOTS.

I had my snows put on and when I left the tire place I did a 40 ft burnout. Now since that should not even be a remote possibility with an almost stock FRS I checked the tires and they were so over pressure they were actually misshaped. Turned around and went back in and they checked pressure. All 4 were at 100psi!!!! Talked to manager and got extended warranty on the tires as at that level of overpressure who knows what damage could show up latter. They had zero explanation as to how it could happen and tires are all the place does.

Sounds like somebody seated the bead and then moved on to the next tire without fixing the pressure. 100psi isnt unheard of to seat a bead, especially if you do heavy duty tires.

Now think about how many tires that guy probably did that day for people who wouldn't notice. :bonk:

New winter tires are going to have taller tread blocks than the used tires you have gotten used to. Winter tire tread blocks flex to grip, you are probably feeling this as well as the slick tread mold coating that needs to be worn off. You can make the tires wear more evenly and last longer if you rotate them front to back every 5,000-8,000 miles. Check the tire pressure as mentioned; most tire shops I deal with inflate tires to their maximum pressure. A sticker on the drivers door jamb will tell you what to set them at.

Very slight mis-match in tire diameter. Worn fronts and worn rears might have just slipped by, Worn fronts and new rears don't make it under the radar. There is a reason why some tire dealers wont sell anything less than 4 new matched tires for some cars.

On a 24 inch diameter tire, a 1/8" diameter mismatch means that the tire with the 24.125" diameter with a circumference of 75.8" will turn 835.9 times per mile while the shorter 24" diameter tire with a circumference of 75.4" will turn 840.3 times per mile.

IF the car is keeping track, it will care about the 5 rotations per mile.

There is a reason I have not sold the MGB yet...not entirely sure I am going to be happy with this level of adult supervision when I play with my toys.

tires take a few hundred miles to break in. mold release compounds take a while to scrub off and out of the rubber. also check air pressures and overall tire diameter on each.

The first words out of my mouth when I went back: "UMMMM did somebody forget to drop the pressure after setting the seal?"
You are also correct in the fact that they do mostly trucks and RVs so would be much more used to the heavy duty stuff then an FRS.
The ironic parts was when they did my wife's RVR the week before all 4 tires were low by about 20psi!
Would have been more pissed if not for the fact that her RV sales company uses them all the time so we got a massive discount on both cars.

time for some burnout

The first thing I did when I got home after the tires were installed was check the tire pressure. It was only 2-3 lbs above recommended, which seemed ok since they were already warm. The next morning I set all 4 exactly to recommended pressure w/ my air compressor.


I'm a bit anal with that stuff, as I even re-torque all my lugs anytime someone touches my wheels. I had a good friend that had a new tire put on, and his shop forgot to tighten down his lug nuts... he pulled over after hearing a rattling and found 2 of his 4 lug nuts had fallen off with the remaining 2 very loose!


Interesting that I'm finding a number on-line comments saying that it's not unusual for tires to take 300+ miles to break in. Now I'm waiting for this CA rain storm to end today so that I can start pushing the car again!

Nice knowing these types of quirks in advance. Thx