indesj01

I got new GMG wheels to replace stock on my 2011 turbo S. They are still 19's. The car rides much more "bumpy" much more noticeable at speeds above 65. Is this normal? Feels like I'm feeling the road more but at times usually when changing speeds from 65-80 or back down to 70 from 80 it gets pretty bumpy. Feels like it's coming from the rear not front. Anyone have a clue what this is? Running new Michelin pilot sport 4s tires.

ScottKelly911

Most likely what you're feeling is the much stiffer sidewalls of the PS4 over the tires you were previously running. What tires were on your stock wheels and how old were they?

indesj01

Thanks for reply. They were 6 years old with 7k mikes pirelli that came on the car

think that will get better? It can get quiet bumpy. My guy checked and rebalanced twice checked everything. Any way one of the wheels is bad? I remember about 12 years ago I put new BBS wheels on my S4 and had a bumper ride due to them being much lighter

Ruskiy

What you're feeling is most likely caused by the tires.

From my experience lighter wheels should give suspension a break and allow for the car ride to actually be more compliant, comfortable and "crash" less over large bumps.

Bad/bent wheels would cause a vibration. Internal damage to the tire such as bent bead would also cause a vibration or difficulty during the balancing. Uncomfortable ride over rough surface, which is what you're describing to me I think, sounds like a tire characteristic more than anything... unless the vibration (bumpy ride) is persistent between specific speeds on all surfaces.

TT Surgeon

If they're balanced correctly you might have a bent rim.
were they new or used?
c

Whosdady

I'm guessing your new wheels are wider and now there is more area to feel every little bump. I noticed this as well on my TTS when I upgraded to wider wheels. I noticed it more so in the rear as the rears had more of a change. I upgraded to the oem gt3rs wheels which aren't as light but look amazing imho. I have spent a lot of time finding the right tire pressure, which has helped the ride quality...

indesj01

Thanks. I also added the DSC module at the same time. It's definately a vibration and more so in rear. Brand new GMG wheels, Michelin PS4s and new DSC module. It is most notable above 75 on highway. It seems to be on every road type and pretty consistent. I'm wondering if bent rim or faulty DSC?

TT Surgeon

Dsc is easy to rule out, Just swap in the stock one then you'll have your answer. I will say that once after my car had been on jacks for a couple of weeks, it was very bouncy with the dsc for about a week then settled out.
its easy to bend a rim, one bad chuck hole or inexperienced installer is all it takes. Could very well be a bent rim too.

indesj01

wouldnt the balancing rule out a bent rim?

TT Surgeon

No, it could balance fine, esp if it's a minor bend. One should be able to see the bend/wobbling during the balancing process.

pfbz

Vibration or bump harshness?

If it's vibration, it is tires or wheels defective or out of balance... Bump harshness, likely inflation pressure or stiffer tires.

Might want to find a shop with a road force balancer.

indesj01

it basically gets up to 80 and cruising just starts bouncing like enough to make my jaws rattle and head ache. it's back in as they are trying to figure it out.