I recently installed a set of 4 Yokohama Avid Touring 195/60R-15 on my '94 850 sedan which just happens to be a Canadian model. The car was purchased from the original owner and has only 62K miles on it. I noticed that the road noise from the new tires was greater that I thought it should be, but I tolerated it. A month later, I installed another set of the same brand/type tire on my '95 850 sedan, but this set was nice and quiet. The '95 has only 90K miles on it. I took the noisy '94 back, had them rotated and rebalanced but no change in the noise. I told the tire store I wasn't satisfied and since only 6K miles were on these tires, the said they would take them and return them to the manufacturer. I then had some Michelin Hydro-Edge tires installed. The road noise remains though not as bad in turns. These Michelins are supposed to be one of the quietest they make and I'm at a loss. The tire store said I might have a problem with my suspension, but with only 62K miles and never driven wildly, what could be the problem compared with my quiet '95 sedan.
The '94 spent the first 5 years of its life in Canada and the last in Virginia. What should I look for or replace. I plan on keeping this car, but can only turn the volume up on the radio so loud to drown out the road/tire noise.

Help, please ............

'86 240DL sedan 293,000 miles original engine & auto transmission
'94 850 sedan 62,000 miles Canadian model
'95 850 sedan 90,000 miles US model