So I changed tire size on my January 2003 MCS from Exclaims 205/40/R17 to Zeon RS3-A 215/45/17. While the sound is much smoother and crossing road expansion joint is less noisy, the unevenness of the road is MUCH more apparent and I feel 'bouncing' all the time. It feel like the car is heavy and shock can handle it so well and sends the shock up my back L. The shocks and suspension are the original with now 68K on them (I don’t get out much..).

Could this be caused by the heavier tire or larger diameter, or the combination thereof? NTB did an alignment when they installed the new tires last week.

Most importantly; what can I do to get the not so shocking driving experience back? Do I need to upgrade/replace my shocks?

 

Why did you go up in profile? If anything that should make the ride softer not firmer. Unless those tires have crazy stiff sidewalls

 

at 10 years and 68k miles it may be time for shocks

ask your mechanic of choice to evaluate your shocks

scott

 

+1 the bouncing effect might be a sign to have them examined.

 

Check your tire pressures.

 

Thanks. I will have the shocks checked out. The reason could be the added weight being moved up/down that the shocks can not compensate for quickly enough, thus the added up/down movement the chassis/frame. Any thoughts welcomed. I did want the incrased in sidewall to smooth out the ride..how ironic..

 

Serisouly, check your tire pressures. Some shops really jack up the pressures after doing any maintenance and taking even a little out really helps ride quality.

It's free and you should be checking tire pressures regularly anyway.

 

I have the Cooper RS3A in the stock 205/45/17 size and they ride and handle smooth.

 

I run a Hankook V12 Ventus Evo 225/50/16 it for sure rides smoother
bit of wobble on turn in but that could be my shocks.
Its likely due to replace your shocks. and check your pressure.

 

Wider tires will follow the road more than thinner ones. Did you have your car aligned with the old tires half worn? This can cause problems when you get new tires.
Your shocks are dead from age, the gas leaks out over time just from sitting. Also you need front lower control arm bushing if yours are still stock. Your bigger tires are working them harder.
Tire pressure also has a large effect on ride

 

I have snow tires in the size you changed to and they are very comfortable. My summers are 205/50/16. Both ride far better that the original runflats.