My wife's 2006 CRV gets the shakes sometimes when the speed hovers at or just above 40 mph. It feels like you're riding over rumble strips on the road. You can feel it in the steering wheel too. Just letting off the gas makes it go away. We've had no luck with the dealer finding the cause. They just charged us for rebalancing the tires and doing an alignment, neither of which helped at all. Now the car is out of warranty and it's still occurring. It's almost as if something is reaching a resonance, like maybe the driveshaft may be out of balance or something? I have no clue what to even look for at this point.