305/30R23
Overall diameter 767.2 mm
305/30R23 — 767.2 mm tall, and what it swaps with
305/30R23 is 305 mm wide with a 30% sidewall on a 23-inch wheel. That sidewall is 91.5 mm, so the tyre stands 767.2 mm tall and turns 414.9 times per kilometre.
- Section width
- 305 mm
- Aspect ratio
- 30 %
- Wheel size
- 23 in (584.2 mm)
- Sidewall height
- 91.5 mm
- Overall diameter
- 767.2 mm (30.2 in)
- Circumference
- 2410.2 mm
- Turns per km
- 414.9
Sizes you can swap to
Only sizes whose overall diameter stays within 3% are listed. A different diameter covers a different distance per turn, and that gap becomes speedometer error.
235/55R20766.5 mm · -0.09% you go slower295/35R22765.3 mm · -0.25% you go slower265/35R23769.7 mm · +0.33% you go faster265/40R22770.8 mm · +0.47% you go faster255/65R17763.3 mm · -0.51% you go slower255/60R18763.2 mm · -0.52% you go slower255/55R19763.1 mm · -0.53% you go slower255/50R20763 mm · -0.55% you go slower235/65R18762.7 mm · -0.59% you go slower265/45R21771.9 mm · +0.61% you go faster265/50R20773 mm · +0.76% you go faster285/40R21761.4 mm · -0.76% you go slower
Same profile, different width
Other sizes for this wheel
How the code reads
The 205 is millimetres, the 55 is a percentage of that width, and only the 16 is inches. The R stands for radial construction.
How to read this
- The first three digits are the width in mm, the middle two are the aspect ratio in percent, the last two the wheel in inches.
- Sidewall height = width × aspect ÷ 100. For 205/55 that is 112.75 mm.
- Overall diameter = wheel diameter + twice the sidewall. A 16-inch wheel is 406.4 mm.
- Once the diameter shifts by more than 3%, the speedometer and odometer drift by the same amount.
Frequently asked questions
Q. What is the overall diameter of 305/30R23?
767.2 mm — the 584.2 mm wheel plus the 91.5 mm sidewall at top and bottom.
Q. How many turns per kilometre does 305/30R23 make?
Its circumference is 2410.2 mm, so 414.9 turns.
Q. What can I swap it for?
12 sizes stay within 3% of its diameter — the closest is 235/55R20 at 766.5 mm.
Q. Why is the sidewall 91.5 mm?
Because it is 30% of the 305 mm width. The aspect ratio is a proportion of the width, not a length.