When I had the car lifted I looked at least at one of them closley and was surprised about the good looks of it. I had the whole car greased and lubed (according to lube/grease points you find in users manual) recently. I do that almost everytime when I had the car in the desert.
The noise is really loud. You can hear it doing 50 or 60mls/h when you go in a tunnel or pass by a wall. You hear it at all speeds when the windows are down, given there's something echoing it. Give me another WE and I do some more searching.

 

What kind of shape are your tires in? What type of tires? If they are cupped or worn they will make a fairly loud slapping noise.

 

New here , but owning a few different off road vehicle , check to see if any rocks are stuck in the tread of your tires , you said when it was lifted off the ground and spun , there was no sound . I have picked up many a rock in tires and it makes a clicking sound , very annoying , usually clears itself with a loud bang as it shoots out , if not have to get a screw driver and pop them out . Just a quick check to look for ..

 

My H1 has a clicking noise coming from the hubs / wheels its been doing it for years ! I've tried every thing !! wish it would go away, I was just waiting for it to get louder so I could find it, no such luck ! it sounds like a little kid with playing cards in his bicycle spokes !!

 

this wont help at all but, this reminded me of a joke i played on my boss. I took a couple zip-ties and a piece of 3/4" rope. I went out to his truck, crawled under it and zip-tied the rope to his driveshaft to where it would hit the fuel tank as it spun. he went a few days before deciding to crawl under there and have a look around. good times!

 

Sounds to my like your CV's are bad. Here, found this

Test drive the vehicle. Evidence of CV joint failure is a clicking or crunching sound, primarily when making turns, vibrations that intensify with acceleration, a humming noise which intensifies with the velocity of the tire or an audible and physical clunk when accelerating and decelerating.


<li class="step">
<li class="step"> 2 Place the vehicle on the side-by car lift (to suspend the suspension) in neutral gear with the steering wheel unlocked and the engine off.


<li class="step"> 3 Put on the safety glasses and gloves and get a shop light.


<li class="step"> 4 Locate the CV joints. All front-wheel drive vehicles have front CV joints. Some all-wheeldrive and four-wheel drive vehicles will have CV joints in the front and rear axles.


<li class="step"> 5 Look at the undercarriage of each wheel and knuckle assembly. A compromised CV boot will have purged thick and pasty lubricant grease as the CV joint spins at high velocity. Clear evidence of the the grease will be coating the chassis components near the CV joint.


<li class="step"> 6 Inspect the outer boots located directly behind each wheel for possible cracking or tearing. Use the shop light for better visual aide and spin the tire to inspect the complete circumference of the boot. Manipulate the wheel outward and then inward (with the steering wheel unlocked and the vehicle in neutral, you will be able to do this from under the vehicle) to compress the accordion shaped boot. Carefully inspect the valleys of the accordion boot as this is a likely area of the boot to begin to deteriorate.


<li class="step"> 7 Visually inspect the shaft of the CV joint for physical damage like being bent. This would cause a severe vibration when driving.


<li class="step"> 8 Follow the length of the shaft to the inner CV joint boot where the joint connects to the transmission. Carefully inspect the boots at this junction as well. Some vehicles will have visible inner CV joint shafts. If so, inspect the boots on them as well.

 

this darn clicking noise ! ok tires are brand new, cv boots look pretty new, its a 99 h1 its looks like the sarge's hummer but it has stock wheels! its like the son I never had. it sounds like a 10 speed bicycle coasting I can tell that Scimitar6 has the same exact sound and its been doing it for three years, no funny smells it runs and drives perfect (hope I didn't just jinks myself) as long as the windows are up you would never know but if your driving next to a wall where it can echo !! Anyway I think it must be bearings in the gear reduction hubs, but they are full of clean gear oil (head scratcher) its like a trivia question at this point ! makes me want to hang on to the skid plate while someone drives it !

 

I ment Joenuzz's hummer, it looks like that!

 

Joenuzz that rope trick is funny I hope you were in the car with him so you could see the look on his face !! LOL thump thump thump !!

 

ok i will tell everyone what that clicking noise is... on your two piece wheels there are chrome plastic caps that snap onto the back of the wheel studs (there are 20 per wheel) that you see on the wheel face. what happens is as the wheel is rotating on the ground the wheel flexes and causes the plastic caps to click with the speed of the hummer. this is mostly heard at slow speed with the window down going past a wall. i have replaced all 80 of them on three alpha hummers and the noise goes away..... for how long i don't know but i have not seen any come back in a years time.