Often times when moving to a larger diameter wheel, a car must use tires with a shorter sidewall height in order to keep the same overall diameter. This concept is called Plus Sizing. Take a look at one of my previous blog posts for additional information. The chart below displays the changes in tire profile when moving up to larger diameter wheels :
In most cases, the larger diameter tires have shorter sidewalls and are referred to as lower profile tires. These tires can have a firmer ride as a result of less sidewall cushioning. However, in many cases, this can be minimized by choosing a tire with a softer ride, such as an all-season tire or touring tire.
For example, a 2008 BMW 335i owner may have a vehicle that comes equipped with the 225/40R18 size in the front and 255/35R18 rear performance tires. This driver then upgrades to a 19" staggered set-up and now uses 235/35R19 fronts and 265/30R19 rears. If the driver chooses a similar summer performance tire, such as the top-rated Michelin Pilot Super Sport, the ride may be a bit stiffer due to having a lower profile tire. If the driver is willing to give up some handling and grip for a tire with a softer ride, he/she could use an all-season tire such as the Continental ExtremeContact DWS.
If you're afraid of losing ride quality when going to larger diameter wheels, check first to see if there are tire options that will alleviate that concern.