I have a problem with vibration/shudder at speeds of 80-90kph (55mph). I have had the tires balanced 3 times including road force balancing. Still the same. Tires have also had been rotated. Unfortunately this happens most of the time but not always. My dealer says they have to contact Mazda engineering on this issue and get back to me. I brought this problem to the dealers anttention at 3000k and I now have 12000k on the vehicle. Any help would be great.

Update
30,000kms on the vehicle and still the dealer can not find a problem.They claim that is just the way the vehicle is! Changed to brand new snow tires and rims and experienced the exact same issue. I am hoping someone else has experienced this issue as i am gettin no where with the dealer