C4S road noise vibration

Hi Guys, I have an 03 C4s. It has what I would describe as pretty loud road noise coupled with a rhythmic vibration that has a pulse to it. It gets worse at speed. It is more of a dull roar and does not come from any particular direction front or rear. At around 2.5Krpm in 6th, you can't hear the engine at all, but the noise levels in the cockpit are quite fatiguing. 1500 miles ago (may), I changed all 4 tires to bridgestone RE050A pole positions. That helped some, but still this issue persists. I have an 80 mile round trip commute and this gets really tiring. I also have another sports car, a Ferrari 348 that I mounted same exact tires (RE050As) at the same time, also 18" wheels, same shop, same balancing machine. The ferrari has near zero road noise. Now the engine and the tubi exhaust make a hell of a racket but if I let go of the gas with the clutch pressed in at speed, the noise is *much* lower than the C4S. So based on this info, while I'd think the tires/balancing could be the culprit, I have a control car that does not have this issue with the ferrari. Like I said, same shop did both cars and they have a very good rep and top of the line balancing equipment. Also, since I tend to drive the ferrari a lot less, so I don't think flatspotting is the problem with the C4S Any ideas? I haven't had the car aligned in 4 years, could that help? Is this something to do with the 4wd transmission? Thanks, -Eric

Just a thought, but a bad/worn wheel bearing will give you a lot of road noise.

I'd also sort out the wheel bearing possibility. I had a front right wheel bearing go bad and noise sounded like it was directly in the middle of the car. I figured it out by doing turns in the school parking lot, first left then right etc...noise stayed the same but slight vibration in steering wheel when car transfered weight to right front wheel. Good Luck

+1 on the above posts. J

Ferrari's are better

Quotes source post: 4667679

LOL! Check wheel bearings. Check tire wear (or uneven wear, aka cupping on the inside). Does the 348 have 295mm wide tires in the rear? 295mm is a wide tire that will produce alot more noise than narrower tires, ESPECIALLY when [unevenly] worn.

Thanks guys. I will check into the wheel bearing, that seems promising. The whole ferrari vs 911 is a separate can of worms, but for me I like both for different reasons Oh and on the ferrari, I put 285 in the rear, so pretty comparable size wise

You can check the wheel bearing by doing figure-8's in an empty lot. If the humming goes away when you transition between left-right turns, it's most likely the bearings.

When I bought my car a year ago the seller said that the tires were noisy and probably needed to be replaced. I was convinced that the tires were cupped or worn unevenly, but my first oil change with a Porsche indy confirmed a front driver's side wheel bearing was bad at just 35k miles. I'm still running those tires and the noise is gone since replacing a wheel bearing. One way to check is to lift your car and spin the tires/wheels...you'll hear the bad beraing.

so I lifted the car to spin the wheels. The front wheels make no noise at all. The rear wheels make no noise if I spin them directly. If I spin the left front wheel, the rear left wheel also spins (this is a C4S) and it is making a noticeable thump thump sound. On the right side this sound is present as well on the rear wheel if I spin the front one, but much less noticeable, you can barely hear it. Does this sound like it could be bad bearings on the rear? thanks!

potxoli, how did this issue pan out for you?