Tire Size Comparison
See any two tire sizes side‑by‑side — to‑scale visual diagram, diameter, width, and speedometer error in one place.
REAL‑WORLD EXAMPLE
Jeep Wrangler JK/JL owners often compare 235/75R15 (≈28.9") or 255/75R17 (≈32.1") stock to the popular 33x12.50R15 (≈33.0") upgrade — that’s a jump of roughly +4.1 inches in diameter (+14%), far beyond the common 3% tire rule and very obvious in the visual diagram below. More subtle: a Toyota Tacoma going from 265/70R17 (≈31.6") to 285/75R17 (≈33.8") looks noticeably taller but is only about +2.2 inches (+7%) — still a significant change for gearing and clearance. Use the Visual, Stats, and Speedometer tabs below to see exactly how any two tire sizes compare side‑by‑side in real dimensions and percentage change.
Enter Tire Specifications
① Original Tire
→ 265/70R17
② Compare Tire
→ 285/70R17
Enter tire specs above and click Calculate to compare
Supports P-metric (225/65R17) and Imperial/flotation (31x10.5R15) formats
Common Tire Size Comparisons — At a Glance
These examples illustrate what "+10mm width" or "+5 aspect ratio" really look like in overall diameter and percentage change. Use the tool above to generate the full to‑scale visual and speedometer impact for each pair.
| Original | Compare | Dia. Diff | % Diff | Visual impression |
|---|---|---|---|---|
| 205/65R16 | 215/65R16 | +0.8" | +3.0% | Slightly taller |
| 225/65R17 | 235/65R17 | +0.4" | +1.4% | Almost identical |
| 225/45R18 | 235/45R18 | +0.4" | +1.5% | Nearly same height |
| 265/70R17 | 285/70R17 | +0.8" | +2.5% | Visibly wider |
| 265/70R17 | 285/75R17 | +2.2" | +7.0% | Clearly bigger |
| 275/65R18 | 295/65R18 | +0.8" | +2.4% | Noticeably wider |
| 31x10.50R15 | 33x12.50R15 | +2.0" | +6.5% | Much taller & wider |
| 245/75R16 | 265/75R16 | +0.8" | +2.6% | Visibly bigger |
Diameter figures are rounded to the nearest tenth of an inch and percentage changes to one decimal place. Real‑world measurements vary slightly by tire model, rim width, and inflation pressure.
How to Use This Tool
- Select your input format — P‑metric (e.g. 225/65R17) or Imperial/flotation (e.g. 33x12.50R15) — for each tire independently.
- Enter your current tire dimensions in the Original Tire panel.
- Enter the size you want to compare in the Compare Tire panel.
- Click 'Calculate & Compare' to generate the side‑by‑side comparison.
- On the Visual tab, toggle between Diameter / Sidewall view and Section Width view to see the to‑scale diagram.
- The Stats tab shows exact numbers — diameter, width, sidewall height, circumference, revs/mile (and km), and ride‑height change.
- The Speedometer tab shows your actual speed at common highway readings and the percentage error versus your original size.
- The Graphs tab offers three chart types: a Bar chart comparing key dimensions side by side, a Radar chart showing a multi-metric fingerprint of both tires, and a Speed Curve plotting actual vs indicated speed across the full range of highway speeds.
About Tire Size Comparison
Numbers alone are hard to interpret. A jump from 265/70R17 to 285/75R17 reads as "+20mm width and +5 aspect ratio" but that doesn’t tell you whether the tire will actually look much bigger. This tool converts those codes into a to‑scale visual and concrete measurements so you can quickly see whether a change is barely noticeable, obviously taller, or large enough to affect gearing and clearance.
P‑Metric vs Imperial / Flotation Formats
Most passenger cars, crossovers, and many SUVs use P‑metric sizing (e.g. 225/65R17), while trucks, Jeeps, and dedicated off‑road builds often use Imperial flotation sizing (e.g. 33x12.50R15). Each tire panel in this tool supports both formats independently, so you can cross‑compare an OEM P‑metric size against an aftermarket flotation size directly using the same visual and numeric outputs.
The 3% Rule & Why It Matters
A common rule of thumb is to keep overall diameter within about ±3% of the factory tire size. Staying close to stock helps keep your speedometer and odometer accurate, maintains ABS/ESC calibration, and reduces the risk of rubbing or drivetrain stress on AWD vehicles. This tool highlights the percentage difference between your two sizes so you can quickly see whether a change falls inside or outside that guideline.
What the Visual Diagram Shows
The Diameter / Sidewall view renders both tires on the same ground line, with circle heights proportional to overall diameter. A +1" change is subtle but visible; a +3–4" jump is dramatic. The Section Width view scales to each tire’s section width so you can see how much more footprint a wider tire adds. Together with the Stats and Speedometer tabs, the visual makes it easy to connect numbers to real‑world appearance and behavior.
Speedometer, Gearing & Fuel Economy
Your factory speedometer assumes a specific tire circumference, so any change in overall diameter alters how far the vehicle travels per wheel revolution. Larger tires typically make the speedometer read slower than your actual speed and reduce engine RPM at a given road speed; smaller tires do the opposite. The Speedometer tab uses the diameter and rev‑per‑mile difference to show how much your indicated speed will differ across common highway speeds so you can plan around it.
Reading the Graphs Tab
The Bar chart plots overall diameter, section width, sidewall height, and circumference for both tires side by side, making it easy to see at a glance which dimension drives the biggest change. The Radar chart renders a multi-metric fingerprint — both tires overlaid on the same axes — so you can spot where they diverge most across all dimensions simultaneously. The Speed Curve charts actual speed against indicated speed from 10 to 90 mph, showing exactly how the error grows (or shrinks) as you accelerate, which is more useful than a single percentage figure when planning highway driving or re-calibrating after a size change.