Get Your Tire Math Right Before You Buy

Free calculators for tire size, wheel offset, gear ratio, load index, and EV-specific fitment. Built by a Detroit shop veteran who has seen too many expensive mistakes.

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8 Free Tools
22 Expert Guides
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📐 Tire Size Calculator ⚙️ Gear Ratio Calculator 📐 Wheel Offset Calculator

🛠️ Our Tools

Every calculator runs in your browser. No data leaves your device. No signup required.

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Tire Size Calculator

Calculate diameter, circumference, revs per mile, and speedometer error for any tire size.
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Tire Size Comparator

Compare two tire sizes side by side and see the difference in width, height, and revs.
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Gear Ratio Calculator

Check engine RPM at highway speed and find the right gear ratio for your tire upgrade.
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Wheel Offset Calculator

See how new wheels will fit, including clearance to suspension and fenders.
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Load Index Calculator

Check maximum weight per tire and compare against your vehicle's requirements.
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Speed Rating Guide

Understand what speed ratings mean and why heat tolerance matters for performance.
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EV Tire Matcher

Find EV-specific tires with the right load index, acoustic foam, and low rolling resistance.
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Plus-Sizing Calculator

Plan your wheel upgrade with recommended tire sizes that keep your speedometer accurate.

📖 Latest Stories

Real-world tire failures, shop-floor lessons, and buyer guides from Detroit.

Plus Sizing Tires Myths Dangers
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Plus Sizing Tires Myths Dangers

July 23, 2026
 Phoenix Heat Tire Blowout Safety
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Phoenix Heat Tire Blowout Safety

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 Tire Shop Sold 19S Manual Said 17S
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Tire Shop Sold 19S Manual Said 17S

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 The Winter Tires I Bought Online That Did Not Fit And The Lesson I Learned
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The Winter Tires I Bought Online That Did Not Fit And The Lesson I Learned

June 29, 2026
 My Mechanic Said My Tires Were Fine
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My Mechanic Said My Tires Were Fine

June 24, 2026
 2026 Tire Trends: All-Weather Tires Are Eating the All-Season Market | Tire Size Hub
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2026 Tire Trends: All-Weather Tires Are Eating the All-Season Market | Tire Size Hub

June 13, 2024
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❓ Common Questions

Do I need to re-gear after bigger tires? What's the difference between all-season and all-weather? Can I use the same tires for winter and summer? Do EVs really need special tires?
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