185/55r16. Suzuki swift.

Am looking into cc6 and D05.

1) How is price and which to recommend? Looked into owner reviews each has it's support from user. But might bias unless they used both on same cars.

2) can my stock rim fit wider tyre ie: 205/55r16 for example? Will my speedometer stay accurate if change wider tyre?

3) Say my speedometer calibrated with rim/tyre size 185/55r16. If i downgrade to 195/X/r15, will it remain accurate?

Not sure on correct term but i hope u guys get the message. Thank you guys.