Based on my experience with a 98 S70 GLT and from I have read here and other places, I have come to the opinion that the only way to improve the ride is by replacing the tires with a smoother riding tire and/reducing the tire pressure. On my car, Volvo recommends 31psi-34psi which I find too harsh. I run a H rated 205/60/15 tire at 28 psi and the ride is much better. Handling may not be as good, but not noticeable. In the winter, I run a 195/65/15 Nokian T rated NRW snow tire. The car rides quite well with this tire. Going down in speed rating obviously will affect the handling. For the average driver who wants comfort, the best compromise in my opinion would be a T rated tire in size 205/60/15 or 195/65/15. The higher profile tires put more rubber between you and the road. Both tires are within 3% of the diameter of the standard 195/60/15 and should not affect the speedometer or ABS systems--at least I have not noticed any difference. The local Volvo dealer puts T rated Cooper Lifeliner STE on their used cars and they seem to ride well. It basically is a tradeoff between handling and smooth ride. I guess in my old age, I prefer the smooth ride.