What changes between these markings
A larger rim does not necessarily produce a larger outside diameter. The rim grows by 25.4 mm, while the two nominal sidewalls together shrink by 28 mm. Those changes nearly cancel, leaving 205/55R16 2.6 mm smaller overall.
With 195/65R15 as original and 205/55R16 as new, nominal diameter changes from 634.5 to 631.9 mm: −2.6 mm (−0.41%). Nominal section width changes by +10 mm and sidewall height by −14 mm per side.
Circumference and theoretical speed
Calculated circumference changes from 1993.34 to 1985.17 mm. Revolutions per kilometer change from 501.67 to 503.73, a +0.41% change. Circumference follows diameter in this circular model; revolution counts move in the opposite direction.
At an indicated 100 km/h, the size-ratio calculation gives 99.59 km/h for the new size. At an indicated 60 mph it gives 59.75 mph. Both examples assume calibration corresponds to the original nominal circumference and ignore existing instrument bias and real rolling deformation.
Keep the comparison direction explicit
The published URL keeps one stable order for this pair. Here 195/65R15 is the original denominator. Reversing the inputs gives a +0.41% diameter change and 100.41 km/h at an indicated 100 km/h. Use Swap in the editable tool to inspect that direction; changing only the sign would be inaccurate.
Half of the diameter difference is −1.3 mm of nominal radius change. It is not a measured ride-height change, and the width difference does not locate the installed sidewall without wheel and product information.
Why this pair has a reference page
A public question puts 195/65R15 and 205/55R16 side by side while asking about ride and handling. This page answers the geometric part of that question; it does not infer comfort from dimensions.
The linked manufacturer entries establish the individual size markings. The public discussion establishes an editorial reason to compare them. Neither source role supplies a fitment approval, search-volume estimate, purchase recommendation or universal acceptable percentage. Check complete vehicle and product requirements separately.
Sources and further reading
- AltiMAX RT45 — General Tire
- Tire comparison for ride comfort and handling — Reddit r/tires
- Tire glossary — Michelin