235/55R20
Overall diameter 766.5 mm
235/55R20 — 766.5 mm tall, and what it swaps with
235/55R20 is 235 mm wide with a 55% sidewall on a 20-inch wheel. That sidewall is 129.25 mm, so the tyre stands 766.5 mm tall and turns 415.3 times per kilometre.
- Section width
- 235 mm
- Aspect ratio
- 55 %
- Wheel size
- 20 in (508 mm)
- Sidewall height
- 129.25 mm
- Overall diameter
- 766.5 mm (30.18 in)
- Circumference
- 2408 mm
- Turns per km
- 415.3
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.
295/35R22765.3 mm · -0.16% you go slower255/65R17763.3 mm · -0.42% you go slower255/60R18763.2 mm · -0.43% you go slower255/55R19763.1 mm · -0.44% you go slower255/50R20763 mm · -0.46% you go slower235/65R18762.7 mm · -0.5% you go slower265/40R22770.8 mm · +0.56% you go faster285/40R21761.4 mm · -0.67% you go slower265/45R21771.9 mm · +0.7% you go faster265/50R20773 mm · +0.85% you go faster285/35R22758.3 mm · -1.07% you go slower245/70R17774.8 mm · +1.08% you go faster
Same profile, different width
Other sizes for this wheel
20-inch wheels
235/35R20 672.5mm235/45R20 719.5mm235/55R20 766.5mm245/30R20 655mm245/35R20 679.5mm245/40R20 704mm245/45R20 728.5mm245/50R20 753mm255/30R20 661mm255/35R20 686.5mm255/40R20 712mm255/45R20 737.5mm255/50R20 763mm265/30R20 667mm265/35R20 693.5mm265/40R20 720mm265/45R20 746.5mm265/50R20 773mm275/30R20 673mm275/35R20 700.5mm275/40R20 728mm275/45R20 755.5mm275/55R20 810.5mm285/30R20 679mm285/35R20 707.5mm285/40R20 736mm285/50R20 793mm295/30R20 685mm295/35R20 714.5mm305/30R20 691mm315/35R20 728.5mm
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 235/55R20?
766.5 mm — the 508 mm wheel plus the 129.25 mm sidewall at top and bottom.
Q. How many turns per kilometre does 235/55R20 make?
Its circumference is 2408 mm, so 415.3 turns.
Q. What can I swap it for?
12 sizes stay within 3% of its diameter — the closest is 295/35R22 at 765.3 mm.
Q. Why is the sidewall 129.25 mm?
Because it is 55% of the 235 mm width. The aspect ratio is a proportion of the width, not a length.