My car makes funny noise at 70-85mph

[WinkOsmosis]

I haven't gone higher than 85.. Around 70, I hear a sound like tires make when rolling over rough road surfaces. Persists if I put the transmission in neutral, so I know it's not the engine/transmission. Any ideas? Could it be uneven tire wear, maybe a flat spot causing some kind of harmonic reinforcement?

1995 240sx

 

[ThaGrandCow]

I had the same problem with 2 separate cars in the past.
Get your tires balanced, possibly realigned. Problem should be solved.

 

[isekii]

it's probably just the tires tread patterns.

Some get unbearably louder after you put certain mileage on em. The best suggestion would be to put more sound dampener to eliminate the road noise.

 

[WinkOsmosis]

Originally posted by: ThaGrandCow
I had the same problem with 2 separate cars in the past.
Get your tires balanced, possibly realigned. Problem should be solved.

Thanks. I think I'm due for a rotation so I'll get a balancing too.

 

[WinkOsmosis]

Originally posted by: isekii
it's probably just the tires tread patterns.

Some get unbearably louder after you put certain mileage on em. The best suggestion would be to put more sound dampener to eliminate the road noise.

Hm. My tires are Dunlop FM901s. They are designed to have low noise by having a varied thread pattern. The tread blocks appear to have varying, random sizes.

 

[Zenmervolt]

Originally posted by: WinkOsmosis
Hm. My tires are Dunlop FM901s. They are designed to have low noise by having a varied thread pattern. The tread blocks appear to have varying, random sizes.

A brief look at Dunlop's own website reveals that the FM901 receives 2 out of 4 "stars" for "Quiet Ride" and it is shown as a high-performace V- or Z-rated tire. That's not going to be a quiet tire any way you look at it.

ZV

 

[WinkOsmosis]

Originally posted by: Zenmervolt

Originally posted by: WinkOsmosis
Hm. My tires are Dunlop FM901s. They are designed to have low noise by having a varied thread pattern. The tread blocks appear to have varying, random sizes.

A brief look at Dunlop's own website reveals that the FM901 receives 2 out of 4 "stars" for "Quiet Ride" and it is shown as a high-performace V- or Z-rated tire. That's not going to be a quiet tire any way you look at it.

ZV

Yeah, but it definately wasn't making this noise before.

 

[fredtam]

Out of balance, uneven wear, or flat spots on the tires. Slam on the brakes recently?

 

[Zenmervolt]

Originally posted by: WinkOsmosis

Originally posted by: Zenmervolt

Originally posted by: WinkOsmosis
Hm. My tires are Dunlop FM901s. They are designed to have low noise by having a varied thread pattern. The tread blocks appear to have varying, random sizes.

A brief look at Dunlop's own website reveals that the FM901 receives 2 out of 4 "stars" for "Quiet Ride" and it is shown as a high-performace V- or Z-rated tire. That's not going to be a quiet tire any way you look at it.

ZV

Yeah, but it definately wasn't making this noise before.

How many miles are on them? Tires, in my experience at least, tend to start getting noisy about 25% into their treadlife and keep getting noisier.

ZV

 

[WinkOsmosis]

Originally posted by: Zenmervolt

Originally posted by: WinkOsmosis

Originally posted by: Zenmervolt

Originally posted by: WinkOsmosis
Hm. My tires are Dunlop FM901s. They are designed to have low noise by having a varied thread pattern. The tread blocks appear to have varying, random sizes.

A brief look at Dunlop's own website reveals that the FM901 receives 2 out of 4 "stars" for "Quiet Ride" and it is shown as a high-performace V- or Z-rated tire. That's not going to be a quiet tire any way you look at it.

ZV

Yeah, but it definately wasn't making this noise before.

How many miles are on them? Tires, in my experience at least, tend to start getting noisy about 25% into their treadlife and keep getting noisier.

ZV

Hmm. About 11,000 miles IIRC.

 

[TechnoKid]

Get your rear diff fluid checked/changed out. You could do this yourself. Make sure you take out the fill plug before you try and take out the drain plug.

Even in neutral, the drive shaft still spins (and the gears in the diff), and low/old gear oil could cause noise.

However, with 11k on those tires, they could be worn already.

 

[Krugger]

Originally posted by: WinkOsmosis
I haven't gone higher than 85.. Around 70, I hear a sound like tires make when rolling over rough road surfaces. Persists if I put the transmission in neutral, so I know it's not the engine/transmission. Any ideas?

yea, slow down...
sorry, no one had said it yet, and you got good suggestions already.