New Wheels + Tires = Vibration

chia · 04-16-2011, 09:16 PM

Hey guys,

I picked up 18" RS-GT replicas for my e36 M3. I've got Hankook V12's 225/40/18 all around.

The small wheels are much different than the stock set up. It feels less stable but it makes turning more agile as a DD. Something I'm willing to live with.

However, on my drive home, there is significant vibrating at the steering wheel and seat at ~100km/h. It didn't feel right, and it was much more uncomfortable then you'd expect just from upgrading to 18" wheels. The car also pulls a bit to the left now.

After a bit of research, they probably either didn't balance the wheels properly or the rims are bent (doubtful).

Called the guys up, and they said it's probably unbalanced - I'm going back there this week, but are there any other issues I should keep in mind?

When I'm cornering at that speed on the highway, the vibrations go away. This should be a clue to something specific.

Thanks for the help.

E36is · 04-17-2011, 09:13 AM

get it rebalanced first (cheapest) could be that the weights on the rim(s) have came off. if not, then could be tie rods or bushings. I would ask them to check if rim is true when they spin it.

propr'one · 04-17-2011, 11:22 AM

^^rommel,

tie rods are a good guess, but if it didn't happen with his old rim/tire setup then that's probably not it.

Have them spun up and balanced, checked for bends, and do an alignment.

Axxe · 04-17-2011, 04:26 PM

I put my money on slightly unbalanced wheels and tired front control arm bushings.

chia · 04-20-2011, 10:42 PM

I just got back from the place today. The re-balance helped a lot, took it for a test drive and it felt better, but not perfect. At ~100km/h there is minor vibrating (sometimes) at the steering wheel, and at the foot well rest.

I went back to the shop and took one of the guys with me for a drive, and it obviously didn't occur. He said that there's ~1oz off balance - is this acceptable?

To add to this, on my drive home, I noticed that there's an increase in shaking when I brake at highway speeds.

blk3 · 04-21-2011, 11:27 PM

maybe you need front control arm bushings. with the larger rubber it puts more stress on the suspension and if you have a couple of bushings with minor play it will be amplified with larger rubber

blk3 · 04-21-2011, 11:28 PM

oh and 1 ounce is quite a bit. a 1/4 ounce you can let go

chia · 06-09-2011, 12:37 AM

You were all correct.

I took it to a tire shop here that I knew had a new and high quality balancing machine.

The first time they balanced it must have been really off. And the second time they just counter-balanced the weights as opposed to re-balancing them.

crxgsr · 06-09-2011, 10:17 AM

Also, if you feel vibration while braking, it's your rotors that need replacing.

and the bit of pulling could be caused by uneven tire pressure between the left side and the right side tires.