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

[Gords_zenith]

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.

[Fish Eagle]

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

[WNDSRFR]

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.

[Tcoat]

Originally Posted by WNDSRFR

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.

[murdoc]

Originally Posted by Tcoat

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.

[MTCRX]

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.

[NOHOME]

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.

[Roadcone]

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.

[Tcoat]

Originally Posted by murdoc

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.

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.

[frslee]

time for some burnout

[996garage]

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!

[FR-STY 86]

Nice knowing these types of quirks in advance. Thx