Tire Conversion Chart: Find Equivalent Sizes from 13-inch to 22-inch Wheels
The Complete Chart for Changing Wheel Sizes While Maintaining Overall Tire Diameter — No Errors, No Crazy ABS Warnings
Every month I get the same question: "I bought 17-inch wheels for my car that originally had 15-inch wheels, what tires should I buy?"
Quick answer: one that maintains a diameter close to the original. Complete answer: it depends on the wheel size, the car, the available width, and the intended use. That's why I'm providing a comprehensive chart for you to consult, along with a calculation formula and practical rules.
Your mechanic will thank you for this guide.
Why Tire Diameter Matters
Modern cars rely on the overall tire diameter for:
- Speedometer (calibrated for exact circumference)
- Odometer (tracks mileage)
- ABS (compares the speed of all 4 wheels — if one decelerates faster, it locks up)
- Stability Control (ESP/VSC/DSC)
- Traction Control
- Electronic Fuel Injection (in some cars, speed affects the mapping)
- Safety Systems (pre-collision, adaptive cruise control)
If you change your wheels and adjust the tires to maintain a similar diameter, everything continues to function normally. If you change them and leave the diameter different, everything becomes an "approximation" — leading to increasing errors.
Rule: a variation of up to 3% is safe. Up to 5% is acceptable. Above that, you might encounter problems.
How to Read Tire Sizes
Ex: tire 205/55/16:
- 205: tire width in millimeters
- 55: aspect ratio — sidewall height is 55% of the width (205 x 0.55 = 112.75mm)
- 16: wheel diameter in inches (16 x 25.4 = 406.4mm wheel diameter)
Overall tire diameter = wheel diameter + (2 x sidewall height) = 406.4 + 225.5 = 631.9mm
Formula for Calculation
Given tire size 205/55/16:
D = (wheel diameter × 25.4) + (2 × width × aspect ratio / 100)
Ex: D = (16 × 25.4) + (2 × 205 × 55 / 100) = 406.4 + 225.5 = 631.9mm
To check if a new size is equivalent, calculate the new diameter and compare:
Variation (%) = (D_new - D_original) / D_original × 100
Equivalency Chart — 13-inch to 22-inch Wheels
Base: 175/70/13 tire (common on older economy cars). D = 575.5mm.
To maintain this diameter across various wheel sizes:
| Wheel Size | Equivalent Size | Diameter (mm) | Variation (%) |
|---|---|---|---|
| 13 | 175/70/13 | 575.5 | 0% |
| 14 | 185/65/14 | 596.1 | +3.6% |
| 15 | 195/55/15 | 595.5 | +3.5% |
| 15 | 185/60/15 | 603.0 | +4.8% |
| 16 | 195/50/16 | 601.4 | +4.5% |
| 16 | 205/45/16 | 590.9 | +2.7% |
Starting from 205/55/16 (Civic, older Corolla, Focus)
D = 631.9mm
| Wheel Size | Size | D (mm) | Variation |
|---|---|---|---|
| 16 | 205/55/16 | 631.9 | 0% (original) |
| 17 | 215/55/17 | 668.3 | +5.8% (high) |
| 17 | 215/50/17 | 646.6 | +2.3% |
| 17 | 225/45/17 | 634.3 | +0.4% (perfect) |
| 17 | 215/45/17 | 625.3 | -1.0% |
| 18 | 225/40/18 | 637.2 | +0.8% (perfect) |
| 18 | 235/40/18 | 645.2 | +2.1% |
| 19 | 235/35/19 | 647.1 | +2.4% |
| 19 | 225/35/19 | 640.1 | +1.3% |
| 20 | 245/35/20 | 679.5 | +7.5% (too much) |
| 20 | 225/30/20 | 643.0 | +1.8% |
Starting from 225/60/17 (Compass, CR-V, Tucson, Tracker)
D = 701.8mm
| Wheel Size | Size | D (mm) | Variation |
|---|---|---|---|
| 17 | 225/60/17 | 701.8 | 0% |
| 18 | 225/55/18 | 704.7 | +0.4% |
| 18 | 235/55/18 | 716.7 | +2.1% |
| 19 | 235/50/19 | 717.6 | +2.3% |
| 19 | 245/50/19 | 727.6 | +3.7% |
| 20 | 245/45/20 | 728.6 | +3.8% |
| 20 | 265/45/20 | 746.6 | +6.4% (too much) |
| 20 | 245/40/20 | 704.6 | +0.4% (perfect) |
| 21 | 265/40/21 | 745.4 | +6.2% |
Starting from 265/65/17 (Hilux SR, Ranger XLT, S10 LT)
D = 776.9mm
| Wheel Size | Size | D (mm) | Variation |
|---|---|---|---|
| 17 | 265/65/17 | 776.9 | 0% |
| 18 | 265/60/18 | 775.3 | -0.2% |
| 18 | 275/60/18 | 787.3 | +1.3% |
| 20 | 275/55/20 | 810.0 | +4.3% |
| 20 | 275/50/20 | 783.0 | +0.8% (perfect) |
| 20 | 285/50/20 | 793.0 | +2.1% |
| 22 | 285/45/22 | 815.3 | +4.9% |
| 22 | 275/45/22 | 806.3 | +3.8% |
Starting from 205/65/15 (Prisma, Classic, 1.0L cars)
D = 647.5mm
| Wheel Size | Size | D (mm) | Variation |
|---|---|---|---|
| 15 | 205/65/15 | 647.5 | 0% |
| 16 | 205/55/16 | 631.9 | -2.4% |
| 16 | 215/55/16 | 642.9 | -0.7% |
| 17 | 215/50/17 | 646.6 | -0.1% (perfect) |
| 17 | 225/45/17 | 634.3 | -2.0% |
| 18 | 225/40/18 | 637.2 | -1.6% |
| 18 | 235/40/18 | 645.2 | -0.4% |
Starting from 195/55/16 (Fox, Polo, Fiesta, Ka)
D = 621.0mm
| Wheel Size | Size | D (mm) | Variation |
|---|---|---|---|
| 16 | 195/55/16 | 621.0 | 0% |
| 17 | 205/45/17 | 616.9 | -0.7% |
| 17 | 215/45/17 | 625.9 | +0.8% |
| 18 | 215/40/18 | 629.2 | +1.3% |
| 18 | 225/40/18 | 637.2 | +2.6% |
| 19 | 225/35/19 | 640.1 | +3.1% |
Using Online Tools
Tire Rack (USA) and 1010tires.com have excellent calculators. Enter your original size + desired size, and it instantly shows the percentage variation.
Brazilian versions: pneufox.com.br/calculadora, and some Brazilian manufacturer pages (Pirelli Brasil, Goodyear).
Practical Rules
1. Acceptable variation: up to 3%. Up to 3%, car systems won't detect a critical difference. From 3% to 5%, it's acceptable with a slight loss of precision. Above 5%, avoid it.
2. If you increase the diameter, the odometer reads less. A tire that's 3% larger → the odometer reads 3% fewer miles than actual. Buying a used car? Check the tire size — if it's larger than original, the mileage might be "understated."
3. If you decrease the diameter, the odometer reads more. Actual mileage will be less than what's recorded. Selling a car? It will show more miles than actual.
4. ABS and ESP self-recalibrate in modern cars. Variations up to 5% are handled without issue. Above that, dealership intervention might be needed.
5. For pickups and SUVs, widths have limits. Tires can be wider than original, but only up to 10-15mm before rubbing the fender. Ex: A Hilux with original 265/65/17 can accept 275/65/17 without rubbing. 285/70/17 might rub.
6. Widths and aspect ratios have an ideal proportion. Increasing width without decreasing the aspect ratio increases the diameter. Example: 225/55/17 (631mm) → 235/55/17 (641mm, +1.6%) → 235/50/17 (621mm, -1.6%). This keeps the diameter close.
Common Mistakes
Increasing wheel size without decreasing aspect ratio. 205/55/16 → 205/55/18 = increases diameter by 50.8mm = +8%. Too much.
Going up two wheel sizes without adjusting. 205/55/16 → 205/55/20 = +101.6mm = +16%. This is impossible, it will rub the fender, and the ABS will go crazy.
Assuming wider tires are always better. 215 vs 225 on an economy car results in more wear, higher fuel consumption, and higher cost. Only use the width your car accepts.
Confusing width and wheel size. A 245 tire has a width of 245mm, not a 24.5-inch wheel. Width and wheel size are different things.
When Recalibration is Needed
If the variation exceeds 5%, consult a dealership. Modern services include:
- Speedometer recalibration via OBD-II
- ABS/ESP reset
- Dynamometer testing
Cost: R$ 200-500. Necessary to keep active safety features functioning correctly.
Golden Rule
Before buying new wheels, do 3 things:
- Note your car's original tire size (it's in the manual or on the driver's side door jamb)
- Calculate the diameter using the formula
- Test new sizes with a calculator — aim for a variation of up to 3%
Then, simulate the wheel on your car — it helps visualize the proportion before buying.
A tire chart is tedious to memorize, but it's golden when you're finalizing a purchase. Save this page and come back when you need it.
Where to buy
Frequently asked questions
Why do I need to maintain the tire diameter? +
What diameter variation is acceptable? +
How do I calculate the overall tire diameter? +
Can I go up two wheel sizes at once? +
If I increase the diameter, will the odometer read less or more? +
Do I need to recalibrate ABS when changing tires? +
What are the "three numbers" on a tire? +
Where to buy
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