I have a 2018 Kia Rio tire size 185/65r15. I have four winter tires on rims from my 2014 Kia Rio size 195/55r16. Iknow there will be a slight difference in speed but will they work(clearance etc ) on my 2018Rio ?
195/55R16 has diameter 195*0.55*2+16*25.4 mm = 620.9 mm
185/65R15 has diameter 185*0.55*2+15*25.4 mm = 584.5 mm
This is a difference of 6.23%. I'd say this is pretty significant, probably making your speedometer reading illegal (car goes faster than what speedometer shows).
195/55R15 would work perfectly, but as yours is 195/55R16 it may be too big.
Oh, and do note that there are numerous specs on the rim, one of the most important ones being bolt circle. A 2018 car may not have all specs the same a 2014 car has. So, you may need to purchase a new set of rims.
Not to mention a decrease in torque and acceleration, the transmission now not being at the ideal speed relative to engine RPM, the possible changing of shift points, the odometer will also be off by the same percentage ...
And the 16" rims may have a different offset, which can be a real problem - potentially unsafe, if there is fender or suspension contact.