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[mke135i]

I just installed a set of Conti DW and at some highway speeds, the whole car vibrates. At 75mph is when it's most noticeable. I can feel the car shaking on my seat, not the steering wheels, so I'm thinking something with the rear tires.
When I had the tires mounted/balanced, they were inflated to 50psi, so I lowered it to 35 but that didn't help. Should I get these tires re-balanced, or is this something else? I never had this issue with my run-flats or my winter tires (on a different set of wheels)

[Javier]

i would say its either an unbalanced tire or a bent wheel

[cssnms]

Road Force Balance them.

[VMRWheels]

It could be an out of balance tire. I would bring it back to the shop to see if they can Road Force the issue.

-Charles@VMRWheels

[Tee212]

Normally if the car shakes then the rear wheels are out of bal. Are the tires brand new? if so just have them rebalance the rears. If youre not running staggered try swapping front to rears for troubleshooting sakes. If they are used tires im guessing internal belt separation would cause the tire not to balance correctly.

[Mr. ///M3 RD]

You may have lost a balance weight or two. It happened to me. I keep a record of balance weight numbers and location on the wheel(s) in reference to the air valve. It helps to double check if you still have all balance weights in position.

Balance weights on new wheels if not properly installed do fly or even fall off. One of my weights fell off just by handling the wheel during change out from summer to winter wheels.

[mke135i]

Thanks for the suggestions. I'm going to get them balanced/checked again. The tires I bought used from a member here, and supposedly have less than 3k miles *they do look very good*. I'll report back once I get them balanced.
One more thing, when i checked the air, the rears had 50psi. Is that right? It seems too much for me (i lowered it to about 40psi but no change). ContiPro DW tires 255/35/18s on the back.

[VMRWheels]

Originally Posted by mke135i

Thanks for the suggestions. I'm going to get them balanced/checked again. The tires I bought used from a member here, and supposedly have less than 3k miles *they do look very good*. I'll report back once I get them balanced.
One more thing, when i checked the air, the rears had 50psi. Is that right? It seems too much for me (i lowered it to about 40psi but no change). ContiPro DW tires 255/35/18s on the back.

50 PSI is extremely high... You'll want to lower that down to around 35-38 or so.

-Charles@VMRWheels

[ALUFELGEN]

Tires could get damaged during mounting/dismounting. Take the care to get Road Force Balanced. The vibration caused by several things including a weight that could have fallen or simply a tire that the technician forgot to balance. I would, however, take the wheels to a facility with a Hunter machine and get them RFB to make sure you could isolate the issue. Reducing the PSI to the suggested 32-38psi will also help.

Matt

[Mr. ///M3 RD]

Originally Posted by AluFelgen

Tires could get damaged during mounting/dismounting. Take the care to get Road Force Balanced. The vibration caused by several things including a weight that could have fallen or simply a tire that the technician forgot to balance. I would, however, take the wheels to a facility with a Hunter machine and get them RFB to make sure you could isolate the issue. Reducing the PSI to the suggested 32-38psi will also help.

Matt

+100

Since he mentioned the high 50 PSI tire pressure I would recommend to FIRST reduce that pressure then drive his car again it might be okay.

[mke135i]

Had all 4 tires re-balanced and tire pressures adjusted. Car rides like new now. Thanks all.