What changes between these markings
Keeping width and rim diameter fixed isolates the aspect ratio. The five-point change produces 10.25 mm more nominal sidewall per side and 20.5 mm more diameter. It does not alter the nominal 205 mm width.
With 205/55R16 as original and 205/60R16 as new, nominal diameter changes from 631.9 to 652.4 mm: +20.5 mm (+3.24%). Nominal section width changes by 0 mm and sidewall height by +10.25 mm per side.
Circumference and theoretical speed
Calculated circumference changes from 1985.17 to 2049.58 mm. Revolutions per kilometer change from 503.73 to 487.91, a −3.14% 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 103.24 km/h for the new size. At an indicated 60 mph it gives 61.95 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 205/55R16 is the original denominator. Reversing the inputs gives a −3.14% diameter change and 96.86 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 +10.25 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
An original Stack Exchange question asks about changing between these 205 mm, 16-inch markings. TireSpan provides the dimension and speed-ratio arithmetic without adopting the answers’ replacement advice.
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
- Can I change my 205/60R16 tires with 205/55R16 tires? — Motor Vehicle Maintenance & Repair Stack Exchange
- Tire glossary — Michelin