Wind resistance can cause buffeting by getting caught under the helmet and acting against the chin
WINDJAMMER 2"REDUCES WIND NOISE" fits all Full Face Helmets. The original often copied ! https://www.amazon.com/dp/B003FHLNVK/ref=cm_sw_r_cp_api_i_EKeyFbTBD2B1W
That’s the product lol
Mileage is more than the tire, it's how you ride. The cupping on the front might be the result of hard braking. 5000 miles isn't terrible, I've gotten 2000 or less. That mileage seems OK if you like the tires. Those short knobs make for a good 50/50 tire.
As far as the noise, wear ear plugs or look to get additional cheek padding or similar for your helmet that might help with the unavoidable noise. Helmets have a lot to do with how noise is transmitted.
I had an agv k3 too. When I used to commute year round I had the same cold issues. Got one of these and it pretty much solved all the cold wind issues. Also grew a large beard. Proline PL82/FS/Bla Windjammer, Black, One Size https://www.amazon.co.uk/dp/B003FHLNVK/ref=cm_sw_r_apan_i_TCH6RDD6J4EBEGNSJDN1
You could try a wind jammer rather than buying a new helmet? https://www.amazon.co.uk/WINDJAMMER-REDUCES-Helmets-original-Worldwide/dp/B003FHLNVK/ref=sr_1_1?ie=UTF8&qid=1467285712&sr=8-1&keywords=windjammer I have heard people only say good things about them reducing wind noise.
Most noise is from wind, you can try using a "motorcycle helmet wind blocker"
You can try a WindJammer (https://www.amazon.com/gp/product/B003FHLNVK). It works if the source of the noise is the neck opening. I've used one for the past year or two and it works OK - it definitely sticks well enough although it makes it bit more difficult to get the helmet on.
Yes, its a problem with Naked bikes generally, however some helmets are designed specifically for that style of riding and cut down on neck strain significantly. I've got a Shoei NXR and the difference is night and day to what I had before. You can also get a windjammer that stops air getting under the helmet, for £12 its a no brainer imo (https://www.amazon.co.uk/WINDJAMMER-REDUCES-Helmets-original-copied/dp/B003FHLNVK)
Also if you've got a gopro or bluetooth module hanging off your helmet take it off. Its amazing how much extra turbulence / resistance they generate at motorway speeds.
Could check this out.
You could try one of these. It is pretty good at keeping wind and noise out.
I picked one of these up last year and it helps a bit, especially in winter. I took it off to install lightmode, but I have better earplugs now
https://www.amazon.com/WINDJAMMER-REDUCES-Helmets-original-copied/dp/B003FHLNVK
I got mine from Amazon, ships from the UK but is only 20 bucks or so.
Really helps and doesnt look bad/weird on the helmet if you mount it right.