Originally posted by 124Addict
duke, thanks for the input. But would like to know also if a tire's speed rating provide any significant difference. Mine is currently z rated.
Yes! Higher speed rated tires have stiffer tread belts and sidewall stiffeners to give them the required stability for higher speed ratings.
I recall reading an article in the WSJ in the mid-nineties about the new S-class. A lot of owners were experiencing significant vibration problems. DB was at a loss to find a fix, and it was causing them a lot of embarrassment. One "fix" was to replace the OE V-rated tires with H-rated tires, but that did not solve all cases.
If anyone remembers this or experienced it, what was the final resolution?
I still have the original wheels and tires for my '88 190E 2.6, but circa 1990 I bought a set of takoff 300E 6.5" wheels and mounted a set of 205/60VR-15 Michelin XGTVs. These were replaced with a set of 205/55ZR-15 Dunlop D40M2s, which had to be replaced with a set of same size/speed rating Dunlop Sport 8000s due to a radial force variation problem.
These lower profile tires did increase ride harshness, but I found it an acceptable tradeoff for the improved steering response and grip. As you go to larger wheel diameters and shorter sidewalls, the harshness will increase and at some point it will become unacceptable, but the crossover point with vary with individuals.
Current models with large diameter short sidewall tires have suspension and subframe bushings specifically engineered for these tires, but ride quality can still suffer. I recently rode in a friends new M3, and it is one of most stiff legged and thumpiest car I have ever ridden in - comparable to older 911s. He also owns a 550 Maranello, which by comparison is smooth as silk, and so is a Z06 Corvette in comparsion to the M3.