My car originals is 185/65/14. To put on 15 and stay with original settings, they state to put on 195/55/15 but I was thinking 205/55/15 better. And as far as size 16 they state to put on 205/45/16, but I was thinkimg 205/50/16 to get more sidewall. Will the sizes 205/55/15 and 205/50/16 fit my car and keep the speedometer working normal, I heard the rule it has to fit under 3% greater or less and both sizes say 1.6% to slow, whatever that means. I live in a place with bad terrain, so potholes are on my way a lot. What size should I get, and the other sizez, will they fit my car and keep the speedometer working normal? Thanks a LOT!!!!