30 or 40 mph is not high enough for vibration due to wheels being off balance. I think there is a different issue, perhaps something with the bearings or suspension components etc. check to see if there is any movement on the wheel when it is jacked up, both grabbing top and bottom (try to pull it from the top or bottom, etc) and also left and right sides, see if the wheel has any play at all. It should have 0 play throughout this process. Also check to see if the wheel lug nuts are loose. Lastly, double check to see if there is any play in the control arms and/or suspension.

it could also be that something in the brakes is loose also.

just some ideas to hunt down.

 

I don't have jacks or jackstands so I'll have to wait till I can use my girl friends fathers stands. Which will probably be tomorrow. I doubt it is something with the brakes seeing how the vibration was occurring before new brakes and after new brakes were installed. Brakes were installed by me, they were done by a local shop.


Edit: I just went out and checked the lug nuts by hand and none of them seem to be loose.

 

actually your wrong. my truck vibrated like crazy at 20-30mph and then even worse at higher speeds above 60mph. it was because my trucks front drivers wheel had its inner wheel weights knocked off.
might check if your balance job was a lifetime or not. if its a lifetime it wont cost you a thing to get them done.
but either way a balance cannt hurt anything!

 

I checked the wheels for any play and I did not notice any. Would getting the wheeles balanced really be worth it since the vibration doens't happen often? Also with the roads around my house they would need balancing again in a very short time. Really I was just hoping there could be a simple fix for this small problem which doesn't seem to be the case.

 

Thats why u pay 10-20 bucks more and get the lifetime balance. u can take it back every week if u think it needs it and it wont cost u any extra after that first lifetime fee.

 

Well I'll take a look into that, but for right now I think it's overdue for a transmission fluid change.