90 SL Tire sizes
 

Book says 225/55/16, wondering if I can go 215/60/16 or 225/60/16.
Not concerned about performance, just fit.

Please post outside diameter and wheel width range for the tires. ( Use Tire Rack for specs )

Generally, if you move 10 narrower on the section width, you need to go up 2 on the aspect ratio but looking at actual tire specs is better.

The lower the aspect ratio, the small the rage of wheel width are acceptable.

Is there a particular reason you want to change tire sizes?