A knocking/ grinding noise has started in the right front wheel area of my captiva. It Started intermittently, but now It's there all the time. It only occurs whilst car is moving and speeds up as the car accelerates/ slows down as car decelerates. Local mechanic looked at it. Tyres all new, but he swapped them around to see if it was tyre noise. He also checked wheel bearings and calipers (which were ok)and pads/ discs, which will need doing in 3000 miles but ok for now. Noise still there . Any ideas? Many thanks!