I have 14" steelies on my LX, and I bought a set of 15" wheels to replace them. I went to tirerack.com and it said I needed 195/60-R15 (which is also the tire size that comes with factory 15" Focus wheels). But I went to Miata.net's tire calculator and when I changed the tire size from 185/65/-R14 (my factory tire size) to 195/60-R15, it said that it would make the speedometer 3.2% too slow. Can someone help me out? Thanks.