255/40R19
Overall diameter 686.6 mm
255/40R19 — 686.6 mm tall, and what it swaps with
255/40R19 is 255 mm wide with a 40% sidewall on a 19-inch wheel. That sidewall is 102 mm, so the tyre stands 686.6 mm tall and turns 463.6 times per kilometre.
- Section width
- 255 mm
- Aspect ratio
- 40 %
- Wheel size
- 19 in (482.6 mm)
- Sidewall height
- 102 mm
- Overall diameter
- 686.6 mm (27.03 in)
- Circumference
- 2157 mm
- Turns per km
- 463.6
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.
255/45R18686.7 mm · +0.01% you go faster255/35R20686.5 mm · -0.01% you go slower215/65R16685.9 mm · -0.1% you go slower225/45R19685.1 mm · -0.22% you go slower295/30R20685 mm · -0.23% you go slower235/60R16688.4 mm · +0.26% you go faster215/60R17689.8 mm · +0.47% you go faster235/55R17690.3 mm · +0.54% you go faster305/30R20691 mm · +0.64% you go faster225/50R18682.2 mm · -0.64% you go slower215/70R15682 mm · -0.67% you go slower235/50R18692.2 mm · +0.82% you go faster
Same profile, different width
Other sizes for this wheel
19-inch wheels
225/35R19 640.1mm225/40R19 662.6mm225/45R19 685.1mm225/55R19 730.1mm235/35R19 647.1mm235/40R19 670.6mm235/45R19 694.1mm235/50R19 717.6mm235/55R19 741.1mm245/35R19 654.1mm245/40R19 678.6mm245/45R19 703.1mm245/50R19 727.6mm245/55R19 752.1mm255/35R19 661.1mm255/40R19 686.6mm255/45R19 712.1mm255/50R19 737.6mm255/55R19 763.1mm265/30R19 641.6mm265/35R19 668.1mm265/50R19 747.6mm275/30R19 647.6mm275/35R19 675.1mm275/40R19 702.6mm275/45R19 730.1mm285/30R19 653.6mm285/40R19 710.6mm295/30R19 659.6mm
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 255/40R19?
686.6 mm — the 482.6 mm wheel plus the 102 mm sidewall at top and bottom.
Q. How many turns per kilometre does 255/40R19 make?
Its circumference is 2157 mm, so 463.6 turns.
Q. What can I swap it for?
12 sizes stay within 3% of its diameter — the closest is 255/45R18 at 686.7 mm.
Q. Why is the sidewall 102 mm?
Because it is 40% of the 255 mm width. The aspect ratio is a proportion of the width, not a length.