Tire Size Calculator — Tire Size Converter & Tire Comparison Calculator

Convert any tire size, compare two sizes side by side with a visual chart, and check diameter, sidewall, circumference, revolutions per mile and speedometer error — free, instant, no sign-up.

Tire Size Converter

Type your sizes below. This tire converter handles metric sizes such as 265/70R17 and flotation sizes such as 33×12.50R17, and it updates every result as you type. Leave the boxes empty and fill in your own tire — you read the size straight off your sidewall.

How to Use This Tire Size Calculator

1. Read the size off your sidewall. Find the code stamped on the tire, such as 265/70R17, or check the sticker on the driver-side door jamb for the factory size.
2. Enter Tire 1 and Tire 2. Type the width, aspect ratio and rim for each size, or paste the full code into the code box. The tire comparison calculator fills the fields for you.
3. Read the tire comparison table. Compare overall diameter, section width, sidewall height, circumference and revolutions per mile, and check the visual overlay chart.
4. Check the verdict and the speedometer table. A diameter change inside 3% keeps your speedometer, odometer and gearing close to stock. The table shows your real speed at every reading.
5. Try the other tabs. The Tire Converter tab decodes a single size, and the Plus Size Equivalents tab lists safe plus-one, plus-two and minus-one alternatives.

Why Use This Tire Size Calculator

• One tool replaces three. A tire size conversion tool, a tire diameter calculator and a tire comparison calculator live on one fast page, so you never jump between sites.
• Visual comparison, not just numbers. The overlay chart draws both tires to scale, the feature drivers love on the Tacoma World tire calculator, alongside the full numeric table.
• Speedometer error in plain sight. You see exactly what 60 mph on the dial means in real speed after the swap, plus the odometer error per 100 miles.
• Gearing answers included. Enter your axle gear ratio and the tool shows your effective ratio and the re-gear that restores stock performance — vital for 33-inch and 35-inch truck tires.
• Both sizing systems. The tire converter moves between metric P-metric and LT sizes and inch flotation sizes in both directions.
• Tap-to-load charts. Every row in the tire chart sections below loads straight into the converter when you tap it.

Who Is This Tire Calculator For

Tire Plus Sizing

Plus sizing means you fit a larger wheel and a lower-profile tire while you keep the overall diameter almost unchanged. A plus-one (+1) swap moves one inch up in rim diameter, a plus-two (+2) swap moves two inches up, and a minus-one (−1) swap moves one inch down — a popular winter move, because a taller, narrower sidewall rides softer and cuts through snow better. The tire grows wider and the aspect ratio drops at every step, so the diameter stays inside the 3% window.

Take a common factory size, 205/55R16 at 24.88 inches tall. A plus-one equivalent such as 205/50R17 or 215/45R17 keeps the diameter within a fraction of a percent, sharpens steering response and fills the wheel arch, while a minus-one 195/65R15 suits a winter wheel-and-tire package. The Plus Size Equivalents tab above generates these matches for your exact size automatically. Remember the trade-offs: lower profiles ride firmer, cost more and protect the rim less against potholes, and wider tires can tramline and drink more fuel.

Tire Conversions

The world runs two tire sizing systems, and a tire size conversion translates between them. Metric sizes (P-metric for passenger cars, LT-metric for light trucks) state the width in millimetres, the aspect ratio as a percentage and the rim in inches. Flotation sizes, common on off-road and classic truck tires, state everything in inches: overall diameter × section width × rim, such as 33×12.50R17.

So a 265/70R17 converts to a 31.6X10.4R17 in flotation terms, and a 33×12.50R17 converts back to roughly a 318 mm wide tire with a 70-series profile — the size the market sells as 285/70R17 (32.7 inches) or 315/70R17 (34.4 inches), depending on the brand. Manufacturers round their moulds, so two tires with the same code can differ by a few millimetres in real diameter; treat every tire conversion as a close engineering figure, not a tape-measure promise.

Popular Tire Size Conversions at a Glance

Tire Size Converter Charts by Wheel Size

These tire size conversion chart tables group popular sizes by the wheel they fit. Every row gives you the overall diameter, width, sidewall, circumference, revolutions per mile and the flotation tire size equivalent. Tap any row and the converter at the top loads that size for you.

Tire Converter Chart for 13″ Wheels

Tire Converter Chart for 14″ Wheels

Tire Converter Chart for 15″ Wheels

Tire Converter Chart for 16″ Wheels

Tire Converter Chart for 16.5″ Wheels

The 16.5-inch wheel is a legacy commercial size. Modern trucks replaced it with 16-inch and 17-inch wheels, so treat 16.5-inch flotation sizes as reference equivalents and confirm availability before you buy.

Tire Converter Chart for 17″ Wheels

Tire Converter Chart for 18″ Wheels

Tire Converter Chart for 19″ Wheels

Tire Converter Chart for 20″ Wheels

Tire Converter Chart for 21″ Wheels

Tire Converter Chart for 22″ Wheels

Tire Converter Chart for 23″ Wheels

Tire Converter Chart for 24″ Wheels

Tire Converter Chart for 26″ Wheels

Tire Converter Chart for 28″ Wheels

Tire Converter Chart for 30″ Wheels

Tire Conversion Charts by Diameter

Drivers who shop by height — “I want a 33-inch tire” — use a diameter-first tire chart instead. These tables group every common size by its overall diameter, so you find every metric and flotation option that stands at the height you want, whatever wheel it mounts on.

22″ Diameter Tire Conversion Chart

23″ Diameter Tire Conversion Chart

24″ Diameter Tire Conversion Chart

25″ Diameter Tire Conversion Chart

26″ Diameter Tire Conversion Chart

27″ Diameter Tire Conversion Chart

28″ Diameter Tire Conversion Chart

29″ Diameter Tire Conversion Chart

30″ Diameter Tire Conversion Chart

31″ Diameter Tire Conversion Chart

32″ Diameter Tire Conversion Chart

33″ Diameter Tire Conversion Chart

34″ Diameter Tire Conversion Chart

35″ Diameter Tire Conversion Chart

36″ Diameter Tire Conversion Chart

37″ Diameter Tire Conversion Chart

41-54″ Diameter Tire Conversion Chart

Oversize flotation tires in the 41 to 54 inch range serve dedicated off-road, mud and agricultural builds. You fit them with substantial lifts, heavy-duty steering and re-gearing, never as a bolt-on street swap.

Tire Diameter Calculator: How Diameter, Sidewall and Circumference Work

A tire size looks like a part number, yet it hides a complete geometry lesson. The tire diameter calculator logic starts with the section width, the widest point of the inflated tire from sidewall to sidewall. Multiply it by the aspect ratio and you get the sidewall height — the distance from the rim lip to the tread. Double the sidewall, add the wheel diameter, and you hold the overall diameter, the single number that decides ground clearance, gearing and speedometer accuracy.

Circumference follows from diameter with π, and circumference decides revolutions per mile: divide 63,360 inches (one mile) by the circumference in inches. A 265/70R17 turns about 638 times per mile; a taller 285/70R17 turns only about 617. Your speedometer and odometer count those turns. Fit a taller tire and each turn carries you farther, so the dial under-reads — at an indicated 60 mph you truly travel 62.1 mph after that swap. The same maths stretches every gear: a taller tire lowers your effective final-drive ratio, blunts acceleration and can push an automatic transmission to hunt between gears, which is why serious 35-inch builds re-gear the axles.

Diameter also sets ride height. Half of any diameter change lands under the axle, so the +1.10 inch diameter of the 285/70R17 lifts the truck by 0.55 inch of ground clearance — and steals the same space from the wheel arch at full steering lock and full suspension compression. Width matters too: a wider tire grows the contact patch sideways rather than lengthways, improves dry grip and braking, and demands the correct rim width range, which the tire maker prints in its spec book.

Two markings complete the picture. The load index states the weight one tire carries at full pressure — index 95 means 690 kg (1,520 lb) — and the speed rating letter states the sustained speed the tire survives at that load, from L at 75 mph to Y at 186 mph. Never fit a replacement with a lower load index than the door-jamb placard demands. The DOT code on the sidewall records the plant and the week and year of manufacture; rubber ages, so most makers advise replacement by six to ten years regardless of tread. Finally, modern cars watch tire size through the TPMS sensors, ABS wheel-speed sensors and stability control, and all-wheel-drive vehicles suffer drivetrain wind-up when rolling circumferences differ corner to corner. Keep all four tires the same size, rotate them on schedule, and treat the 3% diameter rule as your guardrail.

Toyota Tacoma Tire Sizes — the Tacoma World Tire Calculator Alternative

No truck community lives inside a tire calculator like Tacoma owners. Searches for Tacoma World tire size, Tacoma tire size and the Tacoma World tire calculator spike every time a new owner asks the same question: how big can I go without a lift? This table answers it with computed sizes. Tap any row to load it into the converter, then compare it against your stock size in the comparison tab.

The stock third-generation Tacoma wears a 30.5-inch 245/75R16 or a 30.6-inch 265/70R16 — both are “31s” in trail talk once you round honestly, and the calculator shows you why a 265/75R16 at 31.6 inches counts as the classic no-lift upgrade. True 33s (285/75R16 at 32.8 inches, 285/70R17 at 32.7 inches) usually ask for a leveling kit and minor plastic trimming, and they cost you about 7% of your effective gearing. Narrow 255/85R16 “pizza cutters” reach 33.1 inches with the least rubbing, because width causes most clearance trouble. For 35s, budget for a lift, a body-mount chop, upper control arms and a re-gear toward 4.88 or 5.29 — the gear fields in the comparison tab show your exact numbers.

Tire Size Comparison Calculator

Tire code

Every tire carries an alphanumeric code on its sidewall, and you read it in pieces. The opening letters state the intended use: P for passenger cars, SUVs, crossovers and minivans; LT for light trucks that tow and haul; ST for special trailers such as boat and utility trailers; and T for temporary spare tires. No letter usually means a Euro-metric tire.

The three-digit number after the letters gives the nominal section width in millimetres — 265 means the tire measures 265 mm at its widest point. The number after the slash gives the aspect ratio: the sidewall height as a percentage of the width, so /70 means the section height equals 70% of 265 mm, or 185.5 mm. The next letter states the internal construction: R for radial, where the carcass cords run perpendicular to the direction of travel and almost every modern road tire uses it; D for diagonal (bias) construction, where crossed plies run at 30–40 degrees; and B for bias-belted construction, which adds stabilizer belts over a bias carcass.

The number after the construction letter gives the wheel diameter in inches — the rim the tire fits. A final number-and-letter pair states the load index and speed rating, for example 121S on a truck tire. You also find a DOT code on the sidewall: its last four digits record the week and year of manufacture, so 1326 means the tire left the mould in week 13 of 2026.

How is tire size calculated?

You take the width and aspect ratio from the tire code. Multiply the width in millimetres by the aspect ratio percentage and you get the section height in millimetres; divide by 25.4 to work in inches. Double the section height, add the wheel diameter, and you get the overall diameter. For a 265/70R17: section height = 265 × 70% = 185.5 mm = 7.30 inches; diameter = 17 + 2 × 7.30 = 31.61 inches. From that one figure this tire comparison calculator derives circumference (π × diameter = 99.29 inches), revolutions per mile (63,360 / 99.29 = 638) and every speedometer and gearing figure on the page.

What to consider when changing tire/wheel size?

Drivers change tire and wheel size for looks, grip, ground clearance or price — and the change ripples through the whole vehicle. A diameter far from factory spec speeds wear on suspension and brake components, confuses anti-lock brakes and stability control, and alters transmission shift behaviour. Larger rims demand lower-profile tires so the package still fits the wheel well, and the industry guardrail keeps overall diameter within 3% of the factory tire.

Replace all four tires together whenever you can. If budget forces a partial swap, replace at least the pair on one axle, keep the same type and brand on that axle, and never mix sizes across an all-wheel-drive system. Different sizes cause loss of control, spin-outs and damage to stability-system calibrations. And remember the instruments: because speedometers and odometers count tire revolutions against stock calibration, a larger tire makes both read low — you travel faster and farther than the dials claim — while a smaller tire makes both read high. Run your candidate size through the tire comparison above before you buy, and you will know the exact error in advance.

Frequently Asked Questions

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