My R53 seems to have a fair amount of road noise from the back. It dissapears when on a new smooth road so I don't think it can be the start of bearing issues because they would be constant.

It really just seems like road noise getting through. I thought it was my cheap tyres on the back so I just changed them to Dunlop SP Sport 9000 and the noise is much the same. The Dunlop have 5mm tread so while not brand new, must surely be better than my 'Mazzini' ones before.

Is it just normal that the R53 is fairly noisy at the back due to minimal sound insulation?

Is there anything reasonably simple I can do to improve matters?

 

Not much you can do aside from adding additional sound deadening like Dynamat to the rear of the car or changing tires to something like a Continental Extreme Contact DW (quietest summer tires I've ever experienced).

 

I can now answer my own question.

The back is slightly noiser than the fron, BUT the main culprit is my tyres.

I moved the Dunlop to the front and my Michelin to the back. Now the noise is coming from the front mostly.

Bloody hell, I just got the Dunlops hoping for a quieter tyre! They have superb noise ratings, but that goes to show the external rating mean nothing... that or a few mm wear and the quiet is gone.

Michelin Primacy 3 = Big thunbs up
Dunlop SP Sport 9000 = Thumbs down

 

My Cont DW tires have gotten pretty noisy now that they're down to half tread.

 

Typical with those tires. Brand new the set I had "sang" at freeway speeds until alignment was done.

 

Mine roar a bit from 30-50 mph.
Changes with road surface some, and diminishes a bit
or a while if I rotate side to side and front to back.
Some mild feathering which may be contributing to the noise, but
alignment is fine (stock camber front and rear, 0 front toe, 1/16 total
rear toe out - too lazy to reset the rear toe-in for such a small amount).

 

You remember what FINE stands for right ?

If feathering is present it cant be to spec. Or maybe with these DW tires more frequent rotation is in order.

 

Front camber is about -1/2 to -3/4 degree both sides,
Rear camber is about -1.25 to -1.5 degrees both sides,
Front toe in is exactly zero.
Total rear toe (L+R) is 1/16 inch out, both sides about the same.
Didn't measure caster.
Front control arm bushings are PowerFlex and in great shape.
Tie-rods have no play, upper strut mounts are recently replaced and in great shape.


One tire did have a big-ish hole in the tread patched a year or two ago (1/8"- 3/16"),
so there could be a little tread separation, but no thump-thump or obvious signs of that.


The feathering is mild, about what you'd see on half-worn tires on many if not most cars.

 

If your strut's are bad, and the car is riding on the springs (meant to damper, not hold the weight) cars can get louder too....
When the gas and or oil leaks out if a strut...cars tend to think de louder....the ride and handling is obviously impaired too....

 

I changed from 80K old original struts to Koni Yellows last winter,
so not the struts either. I'm thinking it must just be the tires.
The noise is not terrible, just significantly louder than other tires I've had.

 

If you guys want to experience roar...

I run a set of Dunlop Star Specs on my R53. The first time I jumped onto the highway with them on the car, I thought the rear wheel bearings were shot.

 

As a rough rule of thumb, higher performance tires produce more road noise.
That is certainly the pattern here:

Michelin Primacy 3 = Grand Touring Summer
Dunlop SP Sport 9000 = Ultra High Performance Summer
Dunlop Direzza ZII Star Spec = Extreme Performance Summer

The Grand Touring category is aimed towards ride comfort and long tread life rather than performance. It is no surprise that the Michelin Primacy 3 would be quieter.