I'm running 205/40/17
I would like a tiny bit more cushion, can I run 215/45/17 on a 7" wide wheel?

 

What kind of car (model, version, year)? The proper tire size depends on the car, not just on the wheel.

 

99 Si

 

Your car came with 195/55-15 tires from the factory. The proper 17" size for your car is the 205/40-17 you have been using, which has almost exactly the same outer diameter as your stock tires, keeping your speedometer and odometer accurate.

The problem with bigger tires - in addition to the accuracy of the gauges - is that, when you use oversized tires (like 215/45-17) which are 20 mm wider than stock AND whose outer diameter is 5 percent more than stock (which is a HUGE difference), there is a very strong likelihood that the tires will rub on the fender wells and wheel well liners. So getting oversized tires will only create more problems for you. Definitely NOT recommended.

If you are not happy with the ride quality of 205/40-17 tires, then the best way to deal with it would be to go back to your stock 15" wheels with stock sized tires.

 

thanks