What changes between these markings
This pair has the same nominal width but different rims and aspect ratios. The 18-inch rim adds 25.4 mm while its two sidewalls lose 53 mm, so 265/60R18 is 27.6 mm smaller overall. Rim diameter and outside diameter move in opposite directions.
With 265/70R17 as original and 265/60R18 as new, nominal diameter changes from 802.8 to 775.2 mm: −27.6 mm (−3.44%). Nominal section width changes by 0 mm and sidewall height by −26.5 mm per side.
Circumference and theoretical speed
Calculated circumference changes from 2522.07 to 2435.36 mm. Revolutions per kilometer change from 396.5 to 410.62, a +3.56% 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 96.56 km/h for the new size. At an indicated 60 mph it gives 57.94 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 265/70R17 is the original denominator. Reversing the inputs gives a +3.56% diameter change and 103.56 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 −13.8 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
The ClubLexus thread asks about 265/70R17, and its author clarifies the existing marking as 265/60R18. The clarification is the basis for this pair; the thread’s fitment opinions are not reused.
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
- Grabber APT — Specifications — General Tire
- Anyone running 265/70R17 tires? — ClubLexus
- Tire glossary — Michelin